Rubber-Based Sustainable Textiles and Potential Industrial Applications

Abstract

This review explores the evolving landscape of sustainable textile manufacturing, with a focus on rubber-based materials for various industrial applications. The textile and rubber industries are shifting towards eco-friendly practices, driven by environmental concerns and the need to reduce carbon footprints. The integration of sustainable textiles in rubber-based products, such as tires, conveyor belts, and defense products, is becoming increasingly prominent. This review discusses the adoption of natural fibers like flax, jute, and hemp, which offer biodegradability and improved mechanical properties. Additionally, it highlights sustainable elastomer sources, including natural rubber from Hevea brasiliensis and alternative plants like Guayule and Russian dandelion, as well as bio-based synthetic rubbers derived from terpenes and biomass. The review also covers sustainable additives, such as silica fillers, nanoclay, and bio-based plasticizers, which enhance performance while reducing environmental impact. Textile–rubber composites offer a cost-effective alternative to traditional fiber-reinforced polymers when high flexibility and impact resistance are needed. Rubber matrices enhance fatigue life under cyclic loading, and sustainable textiles like jute can reduce environmental impact. The manufacturing process involves rubber preparation, composite assembly, consolidation/curing, and post-processing, with precise control over temperature and pressure during curing being critical. These composites are versatile and robust, finding applications in tires, conveyor belts, insulation, and more. The review also highlights the advantages of textile–rubber composites, innovative recycling and upcycling initiatives, addressing current challenges and outlining future perspectives for achieving a circular economy in the textile and rubber sectors.

1. Introduction to Sustainable Textile Manufacturing and Rubber Industries

Sustainability has become a central theme across industries, including textiles and rubber manufacturing, driven by increasing awareness of environmental concerns and the need to reduce carbon footprints. Both industries are transitioning towards eco-friendly practices by adopting greener raw materials, energy-efficient processes, and waste reduction strategies. The textile manufacturing industry—historically dependent on resource-intensive processes such as high-water consumption during dyeing, energy-intensive spinning and weaving operations, and chemical treatments for fabric finishing and synthetic materials—is now embracing eco-friendly practices to mitigate its environmental impact. Sustainable textile manufacturing involves the adoption of greener raw materials, energy-efficient processes, and waste reduction strategies, aimed at reducing the consumption of non-renewable resources and lowering emissions. From sourcing natural fibers to employing innovative recycling methods, these practices are transforming the textile industry, pushing it towards a more sustainable future [1,2].

In parallel, the rubber industry is also undergoing significant changes. The integration of sustainable textiles in rubber-based applications, such as tires, conveyor belts, and defense products, is becoming increasingly prominent. These products, traditionally reliant on petroleum-based synthetic rubbers and unsustainable textiles, are now being developed with a focus on using bio-based materials and incorporating eco-friendly fibers. The rubber industry is exploring alternative elastomer sources, sustainable additives, and the recycling of rubber materials, which has led to improved environmental performance without compromising on product durability or functionality [3,4].

This review discusses the different approaches towards sustainable textile manufacturing with a special focus on rubber-based materials for industrial applications. It includes sections on eco-friendly fiber and material selection for industrial applications. Examples include natural fibers like flax, jute, hemp, abaca, and bamboo, as well as recycled materials such as recycled polyester (RPET), which are increasingly used in industrial applications. While sustainable practices in textile manufacturing focus on eco-friendly fibers and recycling methods, similar efforts in rubber manufacturing emphasize bio-based elastomers and sustainable additives. The integration of these practices is particularly evident in composite products like tires and conveyor belts that combine textiles with rubber-based materials. Therefore, this review paper also discusses sustainable elastomer sources, highlighting efforts to reduce reliance on fossil fuels in rubber production. Further sections cover different sustainable additives, which are designed to complement eco-friendly fibers and elastomers for various applications. It thoroughly reviews various industrial applications of textile–rubber composite materials, focusing on how these innovative materials are utilized in various sectors. Moreover, this review explores recycling and upcycling initiatives, which are critical in achieving a circular economy in the textile and rubber industries by repurposing materials and minimizing waste.

This review was conducted using a systematic approach to identify and synthesize the relevant literature on sustainable textiles and rubber composites. A comprehensive search was performed in databases such as Scopus, Web of Science, Google Scholar, and Google search, using keywords including ‘sustainable textiles’, ‘rubber composites’, ‘eco-friendly elastomers’, ‘textile recycling and upcycling’, and ‘rubber recycling and upcycling’. The search was limited mainly to the articles published within the last 25 years to ensure the inclusion of the most recent advancements. Studies were included if they focused on sustainable materials, manufacturing processes, applications, and recycling/upcycling of textile–rubber composites in industrial contexts. Data were extracted from the selected articles, focusing on key aspects such as material properties, manufacturing techniques, industrial applications, and environmental impacts. The information was then synthesized and organized into thematic sections to provide a comprehensive overview of the current state of the field.

2. Eco-Friendly Fiber and Materials Selection for Industrial Applications

In recent years, the focus on eco-friendly fibers for industrial applications has grown significantly due to increasing environmental concerns and the demand for sustainable materials. Technical textile products which prioritize performance and functionality over esthetics play a vital role across diverse sectors. In particular, rubber-based textile composites are extensively used in applications such as conveyor belts, expansion joints, inflatable structures, and protective clothing, where flexibility, strength, and durability are essential. Other examples include nonwoven fabrics for filtration systems, geotextiles for construction reinforcement, and coated textiles for industrial hoses and gaskets. These materials are engineered to deliver properties such as abrasion resistance, chemical stability, and elasticity, making them indispensable in demanding industrial environments. Selecting the appropriate fiber depends on balancing performance requirements—such as strength, durability, and flexibility—with sustainability goals like biodegradability or recyclability [5,6]. For example, natural fibers like jute and hemp are increasingly used in composites for automotive interiors, while recycled polyester (RPET) is utilized in industrial fabrics for packaging. In addition to natural and recycled fibers, advanced materials are also gaining prominence. These include aramid fibers (e.g., Kevlar^®) for high-strength, flame-resistant applications, and carbon fibers for lightweight, high-performance composites. Such materials offer superior functionality while aligning with long-term goals of durability and environmental responsibility.

2.1. Natural Fibers

Natural fibers have been used for centuries due to their availability and inherent eco-friendly nature. Fibers like flax, jute, hemp, and ramie have gained popularity in industrial applications because of their better mechanical properties and biodegradability. Flax fiber, for example, is widely utilized in automotive interiors, including door panels, dashboards and seat backs, due to its light weight, high specific strength, and acoustic damping ability [7,8]. Compared to synthetic alternatives like glass fiber, flax offers significant advantages such as lower energy consumption during processing and ease of recyclability [8]. Moreover, the low density of flax contributes to lightweight structures, which is a key consideration in automotive applications aiming to reduce fuel consumption and carbon emissions. Similarly, jute is favored for its high tensile strength, good moisture retention, thermal insulation and biodegradability properties, making it ideal for packaging (Packtech, Eugene, OR, USA) and geotextiles (Geotech, Aurora, ON, Canada). In packaging, jute serves as a durable and sustainable alternative to plastic-based materials, while in geotextiles, it provides soil reinforcement, erosion control, and weed suppression. Hemp fiber is another natural fiber gaining attention for its use in composites, textiles, and construction materials. Besides high tensile strength and resistance to mold and pests, hemp has ecological advantages like minimal pesticide use and low water consumption during cultivation, which makes it an ideal choice for building materials, particularly in eco-friendly construction (Buildtech, Schaumburg, IL, USA) [9,10]. In applications like insulation and reinforcement of concrete, hemp provides both thermal and structural advantages. Furthermore, ramie fiber, known for its high strength and durability, is increasingly used in textiles for industrial applications, especially where the durability of the material is paramount, such as in protective clothing and industrial fabrics. Moreover, abaca and banana fibers exhibit strong potential as sustainable reinforcement materials for polymer and rubber-based composites, offering high tensile strength, biodegradability, and proven industrial applications such as automotive composites [11,12] and rubber-impregnated sheets for durable, flexible materials [13]. In comfort applications, cotton continues to be a favored material, particularly in Clothtech products like workwear and uniforms. Cotton’s breathability, moisture absorption, and biodegradability make it a natural choice for industries requiring comfort combined with sustainability. Lastly, while not typically associated with heavy-duty industrial applications, silk finds relevance in Hometech segments such as high-end home furnishings and curtains. Its natural sheen, smooth texture, and excellent drape make it suitable for luxurious interior applications, where esthetic appeal is as important as functional longevity.

2.2. Synthetic Fibers

While synthetic fibers such as polyester and polypropylene offer superior durability and performance for industrial applications, they are not inherently eco-friendly due to their reliance on petrochemical sources and their non-biodegradable nature. The production of these fibers requires significant energy and fossil fuel consumption, leading to greenhouse gas emissions and depletion of non-renewable resources. Moreover, their resistance to degradation means that discarded synthetic textiles can persist in landfills or the environment for decades, contributing to microplastic pollution in soil and water systems [14]. These materials contribute to environmental pollution and resource depletion, though advancements in recycling and bio-based alternatives are being explored to mitigate their environmental impact [5,15]. A few important synthetic fibers commonly used in rubber-based industrial applications are outlined below [5,6,16,17].

• Nylon (Polyamide): Nylon fibers are widely used in industrial textiles due to their excellent abrasion resistance, tensile strength, and elasticity. They are commonly employed in applications such as hoses, tire cords, conveyor belts, and coated fabrics. However, like polyester, they are petrochemical-based and not biodegradable, though recycling initiatives for nylon (e.g., Econyl^®) are gaining traction.
• Aramid Fibers (e.g., Kevlar^®, Nomex^®): Aramid fibers offer exceptional strength-to-weight ratios, flame resistance, and thermal stability. These are often used in protective textiles, including fire-resistant clothing, ballistic vests, and high-strength composite materials used in industrial reinforcement. Despite their synthetic origin, their long lifespan and high performance contribute to sustainability in demanding applications.
• Recycled Polyester (RPET): RPET, which is generally made from plastic bottles, is suitable for activewear and fleece. It is produced by collecting, cleaning, and melting PET plastics into flakes, which are then re-polymerized and spun into fibers. This process requires significantly less energy and water than producing virgin polyester and helps divert plastic waste from landfills and oceans. It offers a more sustainable alternative to virgin polyester, though concerns about toxic substances like bisphenol A (BPA) remain due to cross-contamination during recycling. BPA is a potentially harmful chemical that can leach out of plastics and has been linked to endocrine disruption in humans. In RPET production, certified recycling processes aim to minimize BPA contamination through rigorous sorting, cleaning, and filtration stages, ensuring the recycled fiber meets safety standards for end use.

While synthetic fibers are traditionally derived from non-renewable petrochemical sources and are non-biodegradable, several innovations are driving their transition toward sustainability. One major development is the use of bio-based monomers, such as bio-derived terephthalic acid (used in bio-PET), which reduces dependence on fossil fuels. Chemical recycling technologies are also gaining momentum, enabling the breakdown of synthetic polymers into their original monomers for reuse, thus promoting a closed-loop lifecycle and reducing plastic waste. In addition, green certification systems such as the Global Recycled Standard (GRS), OEKO-TEX^®, Bluesign^®, etc., ensure environmental and human safety throughout the production and recycling processes [18,19]. These certifications assess factors such as chemical use, environmental impact, and product traceability, helping to ensure that recycled synthetic fibers meet rigorous sustainability standards.

Collectively, these advancements are crucial in mitigating the environmental footprint of synthetic fibers, making them more compatible with the goals of sustainable textile development—particularly when integrated into rubber-based composites for industrial use.

2.3. Advanced Eco-Friendly Fiber Materials

TENCEL^TM or Lyocell fibers or fabrics made from sustainably sourced wood pulp, manufactured in a closed system that minimizes waste and emissions. TENCEL^TM employs a closed-loop manufacturing process that recovers 99.8% of solvents (amine oxide or NMMO) and recycles water [20]. In this closed-loop system, the organic solvent (NMMO) used to dissolve the cellulose is almost entirely recovered and reused in subsequent production cycles, significantly reducing chemical waste. Water used in the fiber spinning process is also filtered and reused, contributing to extremely low freshwater consumption. Moreover, the wood pulp is sourced from sustainably managed forests, and the production process avoids the use of toxic by-products like carbon disulfide (commonly used in viscose production). As a result, TENCEL™ has a lower environmental footprint compared to traditional synthetic and cellulosic fibers, with reduced greenhouse gas emissions, minimal wastewater discharge, and low toxicity. This makes it a model for sustainable fiber manufacturing in the textile industry [21,22]. Key industrial advantages include—(i) high strength (retains 85% strength when wet), (ii) durability, (iii) high moisture absorbency (can absorb 50 times more moisture than cotton, making it an excellent choice for moisture-wicking applications), (iv) resource efficiency (requires much less water than cotton), and (v) circular economy integration (REFIBRA™ technology incorporates 30% recycled cotton waste into fibers, diverting textile waste from landfills) [23]. Industrial applications of lyocell span reinforced rubber tires, anti-vibration components, protective gear linings and many others [24,25].

Bamboo fiber has emerged as a promising eco-friendly alternative to traditional materials like cotton in the textile industry. Bamboo is known for its rapid growth and regeneration after harvesting. Hence, original bamboo fiber or bamboo pulp fibers are the sustainable option for clothing and sustainable industrial applications. Bamboo fiber-reinforced polymer composites have shown potential in various industries such as wind power, construction, automotive, etc., based on their high mechanical strength, low density, and degradability [26].

When selecting eco-friendly fibers for industrial applications, it is crucial to consider different aspects such as performance characteristics (such as strength and durability, weight reduction, energy efficiency, etc.), cost and environmental impact, and biodegradability and recyclability. For example, a comparison of few key aspects has been represented below [27,28,29].

• Mechanical Properties: High-performance fibers like Kevlar^® and UHMWPE exhibit superior tensile strength, impact resistance, and durability compared to conventional fibers. However, they are less flexible and more expensive.
• Cost: Conventional fibers are more cost-effective but may not meet the stringent performance requirements of certain industrial applications (e.g., ballistic protection or high-stress environments).
• Environmental Impact: Conventional natural fibers (e.g., cotton) are biodegradable but may have a higher environmental footprint during cultivation. Synthetic high-performance fibers are non-biodegradable but offer long-term durability, reducing the need for frequent replacements.
• Application Suitability: For example, Kevlar^® is ideal for bulletproof vests due to its high tensile strength, nylon is ideal for tire application, while cotton is preferred for comfort in workwear. Moreover, Nylon 6,6 is extensively used in tire applications, specifically due to its high tensile strength, good heat resistance, excellent fatigue resistance, and good adhesion to rubber.

Therefore, the selection of suitable fiber is crucial for a particular application, considering all these aspects as discussed above.

2.4. Elastomers

The need for sustainable alternatives extends beyond fiber selection to other crucial industrial materials, such as elastomers. Elastomers, like rubbers, are widely used in various industries, and the demand for eco-friendly solutions in this domain has led to the development of new sustainable elastomers [30]. Traditionally, elastomers have been derived from petroleum-based chemicals, which raise concerns similar to those associated with synthetic fibers. However, the introduction of natural rubber (NR) and bio-based synthetic rubbers, along with innovations in additives and vulcanization processes, is paving the way for greener alternatives in rubber-based applications. This shift toward sustainable elastomers highlights the growing commitment to reducing environmental impact while maintaining performance in sectors like automotive, construction, and packaging. Details on sustainable elastomer sources and their applications have been discussed in the following sections.

3. Sustainable Elastomer Sources

Sustainability in the elastomer industry has become a crucial focus due to the extensive use of fossil fuel-derived synthetic rubbers, which cause environmental degradation. This section examines efforts toward more sustainable rubber sources, highlighting both naturally derived and synthetic alternatives that reduce dependence on non-renewable resources.

Synthetic elastomers, which are predominantly petroleum-based, contribute significantly to environmental pollution through high carbon emissions, energy-intensive processing, and challenges in biodegradability [31]. Their production generates hazardous by-products and relies heavily on finite resources, raising concerns over their long-term ecological impact [3,31]. Sustainable alternatives are therefore being pursued to minimize the environmental footprint associated with rubber manufacturing.

3.1. Natural Rubbers

Hevea (Hevea brasiliensis), commonly known as natural rubber (NR), remains the most significant and widely used sustainable rubber. Derived from the sap of Hevea trees, it accounts for approximately 46% of the global rubber market. NR possesses superior mechanical properties, including high tensile strength, fatigue resistance, and tear growth resistance. Its sustainability is enhanced by its natural origin, though concerns about limited plantation areas and susceptibility to diseases prompt the search for alternatives [32,33,34,35]. Guayule (Parthenium argentatum), a woody shrub native to desert regions, offers a promising alternative to Hevea rubber. Its extraction process is more complex, requiring isolation of rubber from trunks, stems, and roots. Guayule rubber typically has lower molecular weight and gel content compared to Hevea NR, which affects its elasticity, processability, and curing behavior. These physical differences may make Guayule more suitable for non-dynamic applications where high elasticity is not the primary requirement, such as medical gloves, rubber linings, or insulation materials. However, its cultivation offers a sustainable source for rubber production, particularly in arid regions [33,34,35]. The Russian dandelion (Taraxacum kok-saghyz) provides another sustainable source of natural rubber, especially under projects like “Taraxa gum”, which aims to reduce reliance on Hevea rubber. Russian dandelion rubber has a high rubber content in its roots and exhibits mechanical properties comparable to Hevea-derived rubber, including good elasticity and tensile strength. Its main advantage lies in its short cultivation cycle and ability to grow in temperate climates, allowing for decentralized and diversified rubber production. However, limitations such as lower latex yield per plant and challenges in mechanized harvesting currently restrict its scalability for mass production. Continued research is being directed toward improving agronomic practices and extraction efficiencies to enhance its commercial viability [34].

Table 1. Different Natural Rubber Sources.

Aspect	Hevea Natural Rubber (NR)	Guayule Rubber (GR)	Russian Dandelion Rubber
Botanical Source	Hevea brasiliensis	Parthenium argentatum (Guayule)	Taraxacum kok-saghyz (Russian Dandelion)
Native Region	South America, now widely cultivated in Asia	Desert regions of Mexico and Southwest US	Kazakhstan, Central Asia
Extraction Process	Tapping latex from the tree trunk	Complex extraction from stems and roots	Roots are leached, latex coagulated
Primary Rubber Component	cis-1,4-polyisoprene (>99%)	cis-1,4-polyisoprene (lower than Hevea)	cis-1,4-polyisoprene (comparable to Hevea)
Polydispersity	2.5–10, bimodal distribution	<2.5, unimodal distribution	Unimodal
Molecular Weight	High molecular weight (104 to 107 Da)	Slightly lower than Hevea	Intermediate between Hevea and synthetic
Key Physical Properties	Stress-induced crystallization, high tensile strength, fatigue resistance	Faster crystallization than Hevea, intermediate green strength	Good tack, comparable tread wear to GR-S, lower tear strength than Hevea
Thermal Properties	Cold crystallization at around 225 °C	Similar thermal stability as Hevea	Similarly to Hevea, improved failure properties
Non-Rubber Constituents	Proteins, fatty acids, lipids, etc.	Less protein, but contains resin acids	Contains ligneous/cellulosic materials, fatty acids
Industrial Applications	Tires (truck, aero), high-performance products	Potential for tires, less stringent applications	Tires, especially eco-friendly applications
Environmental Benefits	Widely used as sustainable resource	Drought-tolerant crop, alternative to Hevea	Promotes biodiversity, reduces reliance on Hevea
Challenges	Risk of diseases, limited plantation areas	Complex extraction, lower performance in some properties	Lower stress-induced crystallization, ongoing research for optimization
Environmental Impact	Requires high rainfall and large land area; use of agrochemicals and pesticides may affect local ecosystems	Low water requirement, grows in arid regions; lower pesticide use; minimal deforestation risk	Can grow on marginal land, supports crop diversity; short cultivation cycle reduces environmental load

provides a comparison of different natural rubber sources.

Apart from hevea, guayule, and dandelion, there are few other plants that produce cis-1,4-polyisoprene. Goldenrod (Solidago altissima) and Jelutong (Dyera costulata) are notable. Various plants producing cis-1,4-polyisoprene are presented in Figure 1.

3.2. Sustainable Synthetic Rubbers

The development of synthetic rubber has significantly expanded the range of elastomeric materials available for industrial applications. Since the initial successful synthesis of polyisoprene in 1887, numerous variations in artificial rubbers have been created, with over 20 types currently available in the market. Synthetic rubbers offer a diverse array of properties that can be tailored to specific applications, complementing and extending the capabilities of natural rubber. This versatility stems from the ability to engineer synthetic rubbers using various monomers, resulting in a wide spectrum of material characteristics. In contrast, natural rubber typically exhibits a single chemical structure, limiting its property range. The innovation in synthetic rubber technology has significantly benefited a range of sectors, including automotive (e.g., tires, seals), aerospace (e.g., vibration isolators), construction (e.g., waterproofing membranes), healthcare (e.g., medical gloves), and electronics (e.g., wire insulation), owing to the tunable properties of synthetic elastomers. The evolution of synthetic rubber technology has led to its widespread adoption across multiple industries using different synthetic rubbers such as styrene butadiene rubber (SBR), chloroprene (Neoprene), butyl rubber (IIR), nitrile rubber (NBR), and ethylene propylene diene rubber (EPDM), etc. Despite these advantages, conventional synthetic rubber production poses environmental challenges due to its dependence on petroleum feedstocks and energy-intensive manufacturing processes. Issues such as greenhouse gas emissions, hazardous waste generation, and non-biodegradability highlight the need for sustainable alternatives [3,31].

As an alternative to the above natural sources, terpenes, naturally occurring compounds found in plants, are being explored as sustainable alternatives for synthetic rubbers. Terpenes represent a promising class of sustainable feedstocks for synthetic elastomers [36,37,38,39,40,41]. Common sources include pine trees, citrus peels, eucalyptus, and lemongrass, which are rich in monoterpenes like limonene, pinene, and β-myrcene. Terpenes are secondary metabolites produced by various plants, particularly conifers, as well as some fungi and marine organisms. Their potential lies in their structural similarity to petrochemical-based elastomers, particularly their isoprene-like chemical structure (Figure 2a), which makes them suitable for synthetic rubber production. β-Myrcene, a terpene derived from coniferous plants, has shown potential in the synthesis of polymyrcene elastomers (Figure 2b), offering comparable properties to traditional synthetic rubbers like SBR. Polymyrcene’s industrial application is being investigated for tires and other rubber goods, reducing reliance on petrochemicals [37,38,39,40].

Efforts are also focused on producing rubber-like materials from biomass-derived monomers, including isoprene and butadiene. By employing biotechnology to ferment sugars into isoprene or transforming agricultural waste into rubber monomers, these approaches contribute to a circular economy in elastomer production. Biomass-derived monomers have been reported to demonstrate comparable performance to their petrochemical counterparts in several rubber applications. Compared to petrochemical-derived monomers, biomass-based counterparts can reduce carbon footprint and reliance on finite resources. The adoption of biotechnology has also enabled a more controlled and selective production of target monomers, enhanced yield efficiency and reducing byproduct generation, thereby improving the overall market viability of sustainable synthetic rubber materials. However, challenges such as lower yields, higher production costs, and scalability must be addressed [3,4,31].

Table 2. Overview of biobased monomers for rubbers.

Biobased Monomer	Source	Synthesis Method	Applications/Key Attributes	Environmental Impact
Isoprene	Populus alba, plant sugars	Biotechnological pathway, fermentation of plant sugars	Bio-Isoprene for tire production, reduces dependence on fossil fuels	Reduces GHG emissions compared to petrochemical isoprene; utilizes renewable feedstocks
1,3-Butadiene	Biomass-derived furfural	Catalytic ring-opening dehydration of tetrahydrofuran	Used in synthetic rubbers like SBR, NBR	Lower toxicity pathway, but still requires energy-intensive catalysis
Acrylonitrile	Glycerol, glutamic acid	Catalytic conversion via acrolein intermediate	Key monomer in NBR and engineering plastics	Reduces fossil fuel use, but process involves toxic intermediates
Styrene	Forest waste, sugar	Fermentation and decarboxylation of Penicillium expansum, E. coli	Used in SBR, biobased polystyrenes	Uses agricultural waste, reduces oil dependence
Chloroprene	Lime, coke (from natural resources)	Produced via acetylene from lime and coke	Monomer for polychloroprene elastomers	Still dependent on mineral resources; hazardous intermediates
Farnesene	Sugarcane, plant-derived	Fermentation pathway	Low-temperature ice-grip tires, elastomer additive	Carbon-neutral potential if integrated with sustainable agriculture

provides an overview of biobased monomers, their sources, synthesis methods, and applications. A schematic representation of conversion of sustainable and renewable feed stocks to renewable biobased monomers and their transformation to finished products is presented in Figure 3.

4. Sustainable Additives

Rubber additives play a crucial role in improving the performance of rubber products, and the search for sustainable alternatives is becoming more prevalent as part of green chemistry efforts. Traditional additives, such as fillers, plasticizers, and antioxidants, often come from non-renewable petrochemical sources or involve environmentally harmful processes. Sustainable alternatives aim to reduce environmental impact while maintaining or improving the performance of rubber products [41,42,43].

4.1. Fillers

Fillers improve the mechanical properties of rubber, including strength, hardness, and wear resistance. Traditionally, carbon black has been the most widely used filler, but sustainable alternatives such as silica and clay are gaining prominence. Silica is now a key sustainable filler, particularly in tire manufacturing, due to its ability to reduce rolling resistance, which leads to improved fuel efficiency and lower carbon emissions [40]. Unlike carbon black, silica interacts more effectively with functionalized polymers, resulting in better energy dissipation and enhanced wet traction [40,41]. These advantages make silica more environmentally favorable, especially when considering end-use vehicle emissions.

Although silica offers environmental advantages in performance applications, the sustainability of its production depends on energy consumption during processing. Compared to carbon black, which is derived from the incomplete combustion of fossil fuels and results in high carbon emissions, silica production, especially from rice husk ash or other bio-based sources, can result in lower greenhouse gas emissions and reduced dependence on petroleum-based raw materials. Michelin’s “Green Tires”, which use silica instead of carbon black, have demonstrated a 3–4% improvement in fuel economy and better wet grip, contributing to sustainability in the automotive industry. Nano-fillers such as nano-silica and nano-clay are also being researched for their ability to enhance performance with lower material usage, further contributing to sustainability goals [43,44,45,46,47].

Different types of natural and modified nanoclays especially 2:1 phyllosilicate (smectite), for instance montmorillonite, bentonite, hectorite, laponite, saponite, vermiculite, and sepiolite have great potential to be used as sustainable fillers for manufacturing polymer/clay or rubber/clay nanocomposites improving their properties [35,44,45]. Bhattacharya et al. [45] explored the development of organic–inorganic nanocomposite hybrids using SBR with various nanofillers, including modified and unmodified montmorillonite, hectorite, sepiolite, carbon nanofiber, and expanded graphite. The study highlighted significant improvements in mechanical properties: Cloisite 15A increased tensile strength by 230% at 8 phr loading, while carbon nanofiber enhanced the modulus by 101% and tear strength by 79% at 6 phr. Modification techniques further optimized these properties, with Cloisite 15A showing a 146% increase in modulus and 303% in tensile strength, and carbon nanofiber demonstrating a 150% increase in modulus and 113% in tensile strength. The enhanced properties are attributed to mechanisms such as intercalation and London dispersive forces.

These specific clays were selected due to their layered structures, high aspect ratios, and surface chemistry, which facilitate strong interactions with rubber matrices. Modified clays often exhibit better dispersion and interfacial adhesion than natural clays, contributing to enhanced mechanical, thermal, and barrier properties in rubber composites [46,47,48]. Researchers have developed ternary nanocomposites combining natural rubber with sepiolite and carbon black, as well as with carbon nanofibers and carbon black. These composites showed superior mechanical, dynamic mechanical, and tribological properties compared to binary systems involving natural rubber with clay, carbon nanofibers, or carbon black alone [49]. A comparative summary of key filler types has been shown in

Table 3. Comparative summary of key filler types.

Filler Type	Source	Mechanical Performance	Environmental Impact	Application Notes
Carbon Black	Fossil fuel-based	High strength	High carbon emissions	Traditional tires, industrial rubbers
Silica	Natural/mineral or biomass-derived	Good wet grip, lower rolling resistance	Lower emissions if bio-derived	Green tires
Natural Clay	Mined	Moderate	Low	Reinforcement in composites
Modified Clay	Chemically treated clay	High (due to dispersion)	Moderate	Advanced rubber nanocomposites
Nano-fillers (e.g., nano-silica)	Synthesized	Excellent at low loadings	Dependent on synthesis method	High-performance, lightweight rubbers

to clarify differences in performance and environmental impact.

4.2. Plasticizers

Plasticizers enhance flexibility and processability in rubber compounds. Traditional plasticizers like phthalates are associated with endocrine disruption, bioaccumulation, and toxicity to aquatic life, raising serious environmental and human health concerns [50]. Sustainable alternatives, including bio-based oils derived from vegetable sources, are now being explored. Soybean oil offers good compatibility with rubber matrices and is widely available, while castor oil provides high plasticizing efficiency due to its hydroxyl groups, though it may be costlier and more viscous [51,52]. These bio-oils offer similar performance while reducing reliance on fossil resources. Epoxidized vegetable oils, for example, have shown promise as a plasticizer in rubber applications, providing good mechanical properties with a lower environmental footprint. Epoxidized oils, such as epoxidized soybean oil, contain reactive epoxy groups that improve compatibility with rubber chains and enhance oxidative stability. These oils offer reduced toxicity, are biodegradable, and present lower greenhouse gas emissions compared to petroleum-based plasticizers [52,53,54].

4.3. Antioxidants

Antioxidants are essential for protecting rubber from oxidative degradation, which can shorten the lifespan of rubber products. Antioxidants stabilize rubber by donating hydrogen atoms or electrons to neutralize free radicals generated during oxidative degradation, thus preserving the integrity of polymer chains [55]. Traditional antioxidants, such as amine-based compounds, are effective, but have potential environmental and health concerns. Amine-based antioxidants, while effective, can degrade into nitrosamines, which are known carcinogens, and are linked to aquatic toxicity. Bio-based antioxidants derived from plant polyphenols avoid such issues, offering safer degradation products and reduced environmental toxicity [53,55]. Research into bio-based antioxidants has identified natural phenolic compounds as promising alternatives. These bio-based antioxidants are derived from renewable sources such as plant extracts and have shown effectiveness in preventing oxidative degradation in rubber materials [3,56,57].

Common sources include green tea, grape seed, and olive leaves, which are rich in catechins, flavonoids, and other phenolics. These compounds are effective due to their radical-scavenging ability, though challenges such as cost, variability in composition, and limited large-scale supply persist.

4.4. Vulcanization Accelerators

Vulcanization is a key process in rubber manufacturing, where sulfur cross-linking is induced to improve the strength and elasticity of rubber. Vulcanization accelerators significantly influence cross-link density, affecting elasticity, tensile strength, and durability. Faster and more efficient cross-linking contributes to improved mechanical and thermal properties [53,56]. Zinc oxide (ZnO) is commonly used as an activator in the vulcanization process. Although ZnO is effective, its environmental impact, including the presence of impurities like cadmium oxide, has raised concerns. Nano-ZnO provides a higher surface area, allowing effective activation at lower concentrations. This reduction in required material quantity decreases zinc leaching into the environment, thus reducing toxicity and ecological impact [56]. The development of nano-ZnO has shown promise, offering greater efficiency with lower usage, thereby reducing the environmental load [3,58,59]. Further, alternatives like zinc chelates and other bio-derived accelerators are being studied for their potential to replace traditional petrochemical-based activators. Figure 4 represents the list of sustainable rubber additives and their bioresources.

5. Textile–Rubber Composite Materials

Textile-reinforced polymer composites, particularly those incorporating rubber matrices, play a crucial role in modern society. These materials, often operating inconspicuously, are integral to numerous essential systems. For instance, transportation infrastructure relies heavily on rubber–textile composites in tire construction. Similarly, materials handling processes depend on conveyor belts and hoses composed of rubber–textile laminates for solid and liquid transport, respectively. Additionally, mechanical power transmission systems utilize rubber–textile drive belts. Hence, the importance of textile-reinforced polymer composites, particularly those with rubber matrices, is well-established across industries such as transportation and material handling. While their ubiquity is notable, it is important to clarify their performance characteristics in comparison to other composite materials. For instance, textile–rubber composites often provide a cost-effective alternative to traditional fiber-reinforced polymers with thermosetting matrices in applications where high flexibility and impact resistance are required. In terms of durability, studies have shown that rubber matrices can enhance the fatigue life of composites under cyclic loading conditions, making them suitable for applications such as tire [58]. In an interesting study, Shaik et al. [13] reported that the abaca/epoxy composite exhibited 27.5% higher impact resistance, while the abaca/rubber hybrid composite showed an 11.2% higher impact energy and longer impact duration due to the rubber ply altering the impact characteristics and damage mechanism. Furthermore, the use of sustainable textiles like jute or hemp can reduce the overall environmental footprint and material costs compared to synthetic fiber composites. However, it is worth noting that textile–rubber composites may not always match the stiffness and high-temperature resistance of advanced composites with carbon fibers and epoxy resins [12,59]. Therefore, the selection of composite material should be based on a comprehensive evaluation of performance requirements, cost considerations, and sustainability goals.

Rubber coated textiles are built upon carefully selecting premium base materials, mainly woven fabrics and sometimes braided or knitted fabrics made of conventional fibers/filaments (cotton, polyester, nylon, silk, etc.) or high-performance fibers [glass, ultra-high molecular weight polyethylene (UHMWPE), Kevlar^®, carbon, etc.]. Figure 5 shows the common fabric forms used in textile–rubber composite materials. To manufacture textile–rubber composites, the appropriate rubber compounds such as natural rubber (NR), nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), silicone rubber (VMO), flurosilicone rubber (FVMO), chloroprene, styrene-butadiene rubber (SBR), butyl rubber, ethylene propylene dine monomer (EPDM) rubber, chlorosuphonated polyethylene rubber (CSM, hypalon), perfluoro elastomer (FFKM), blended polymers, etc., are applied on the textile fabric. Different rubber types are chosen based on their unique properties, which align with specific application requirement. For instance, NR is known for its excellent tensile strength, elasticity, and fatigue resistance, NR is widely used in applications requiring high mechanical performance and dynamic applications, such as tires and conveyor belts [60]. NBR offers superior resistance to oils and chemicals, making it suitable for industrial hoses, seals, and gaskets. HNBR provides enhanced thermal stability and resistance to ozone layers and weathering, which is ideal for automotive belts and seals operating under extreme conditions. EPDM excels in weather resistance and electrical insulation, making it a preferred choice for outdoor applications like roofing membranes and automotive weather seals [61]. Figure 6 summarized the temperature tolerance range of different rubbers, which can be useful for selecting suitable rubber materials based on application temperature of the textile–rubber composites. Among nonfluorinated rubbers, silicon rubber and EPDM are selected for high-temperature environments due to their thermal stability. For example, silicon can withstand temperatures up to 230 °C. NBR is favored in environments exposed to oils or fuels due to its excellent chemical resistance.

6. Manufacturing Textile–Rubber Composites

Rubber composites, also referred to as plied rubber, represent a class of advanced materials that synergistically combine the unique properties of elastomers with various reinforcing substrates. These innovative composites are engineered by strategically integrating rubber layers with reinforcing materials such as textiles or metallic components, resulting in products with enhanced mechanical strength, flexibility, and durability. The design of rubber composites involves several critical considerations such as material selection, structural design, interfacial bonding, and dimensional precision. In summary, the manufacturing process for rubber composites typically encompasses the following four stages.

(i)

Rubber preparation

Rubber compounding is an essential aspect of rubber technology. The rubber is mixed with different additives or fillers to achieve specific properties such as strength, elasticity, resilience, and chemical resistance. The additives include reinforcing fillers like carbon black and silica, which improve tensile strength, tear resistance, and abrasion resistance. For instance, carbon black increases the stiffness and hardness of the rubber matrix, while silica enhances the rolling resistance and wet traction in tire applications [63].

Other additives include plasticizers, such as bio-based oils and esters, which improve flexibility and processability by reducing the glass transition temperature of the rubber. Antioxidants and antiozonants are also crucial for protecting the rubber from degradation due to heat, oxygen, and ozone exposure, thereby extending the service life of the composite. Furthermore, activators, vulcanizing agents or curing agents like sulfur, and accelerators (which speeds up the vulcanization process) are used to promote cross-linking by forming stable covalent carbon–carbon double bonds in the rubber matrix, which enhances the elasticity and resilience of the rubber matrix [64,65].

Table 4. Typical rubber compounding ingredients and respective [66].

Compounding Ingredient	Dosage Range (phr)
Elastomer (base polymer)	100
Vulcanizing agent	0.5 to 35
Accelerator(s)	0.5 to 5
Activators	1.0 to 5
Antioxidants	0.5 to 2
Filler	25 to 200
Pigment	5.0 to 100

provides an overview of the common ingredients utilized in rubber compounding for the fabrication of rubber composites.

The specific choice and concentration of these additives depend on the desired final properties of the composite, such as mechanical strength, durability, and environmental resistance. For example, in applications requiring high tensile strength and abrasion resistance, a combination of carbon black and a sulfur-based curing system may be employed. In contrast, for applications where flexibility and low-temperature performance are critical, bio-based plasticizers and alternative curing systems may be preferred [67,68].

(ii)

Composite assembly

Integrating the prepared rubber with chosen reinforcing materials (textile and metals) using a variety technique such as calendaring, extrusion, or lamination. Calendaring involves pressing rubber and textile layers together between rollers to create a unified composite. Extrusion encases textiles or metal wires within a rubber matrix as the material is forced through a die. Lamination bonds textile or metal layers to rubber sheets using adhesives and pressure, often followed by curing [69]. Each technique significantly influences the final properties of composites; for example, calendaring ensures strong adhesion and uniform thickness, while extrusion provides a robust encapsulation for reinforcement. Lamination allows for combining diverse materials, optimizing specific properties like tear resistance or flexibility. The choice of integration technique depends on the desired mechanical, thermal, and chemical properties of the final composite.

(iii)

Consolidation and curing

Applying adhesive systems between layers and subjecting the composite to controlled heat and pressure to facilitate bonding and achieve desired material properties. Temperature and pressure control during curing are critical as they directly influence the cross-linking density and uniformity of the composite material, which in turn affects its mechanical properties such as strength, stiffness, and durability. Precise control ensures optimal cross-linking, while non-uniform conditions can lead to stress concentrations and premature failure. Alternative curing methods like microwave curing [70], UV curing [71], and induction heating [72] are being explored to achieve faster curing times, reduce energy consumption, and improve control over the curing process.

(iv)

Post-processing

Trimming the composite to required dimensions and performing any necessary finishing operations, such as surface treatments, precision cutting, edge sealing, and surface texturing. Applying coatings such as polyurethane or epoxy resins can enhance abrasion resistance, UV protection, and chemical resistance [73,74,75]. For example, polyurethane coatings improve the wear resistance of rubber–textile composites used in conveyor belts [76]. Laser cutting or waterjet cutting is used to achieve precise dimensions and intricate designs without compromising the structural integrity of the composite. Waterjet cutting is particularly useful for preventing heat-induced damage in the textile component [77]. Sealing the edges of the composite prevent moisture ingress and fraying, which can compromise the strength and durability of material. This is especially important in applications where the composite is exposed to harsh environmental conditions [78]. Moreover, creating specific surface textures improves grip, reduces friction, and enhances esthetics. This can be achieved through techniques like embossing or molding [79].

7. Industrial Application of Textile–Rubber Composite Materials

Rubber-coated fabrics are very versatile, robust, and long-lasting, making them well-suited for a wide range of uses in tires, conveyor belts, insulation, defense, aviation, aerospace, marine, offshore industries, etc. Few specific industrial applications of textile–rubber composite fabrics have been summarized below.

7.1. Tires

One of the most significant and widespread applications of textile–rubber composites is in the tire industry. Modern tires rely heavily on the synergy between rubber compounds and textile reinforcements to provide the necessary strength, flexibility, and durability required for various vehicles [80]. The use of textile reinforcements in tires offers several advantages such as enhanced strength-to-weight ratio, improved fuel efficiency due to reduced rolling resistance, and better heat dissipation which leads to increased tire life and superior handling and stability at high speeds. The textile component, typically made of materials like polyester or nylon, forms the structural skeleton of the tire, while the rubber provides the necessary grip and resilience.

Specific Materials in Textile–Rubber Composite-Based Tires

A tire contains many textile components, including casting belt breaker fabric, chafer fabric, bead wrapping fabric, filler fabric, and tire cable fabric (Figure 7). Nylon 6 and Nylon 6,6 are extensively utilized for tire cables, with Nylon 6 being the predominant choice. Polyester is utilized in body plies and bead wrapping materials. The reasons behind the extensive use of polyester and nylon in tire industry are their excellent mechanical properties, durability, and thermal stability. Specifically, polyester is known for its high tensile strength, dimensional stability, and resistance to heat, polyester enhances the structural integrity of tires. It also exhibits low creep under sustained loads, making it suitable for applications requiring long-term durability. Moreover, nylon offers superior elasticity, abrasion resistance, and fatigue resistance under dynamic conditions. These properties make nylon ideal for reinforcing tire components subjected to continuous flexing and stress during vehicle operation. In an interesting study, Naskar et al. [81] compared the physical properties of polyester, Nylon 6, and Nylon 6,6 tire cords. Polyester exhibited poor fatigue resistance, failing under high strain levels (±15%) after 120 h of continuous testing. In contrast, Nylon 66 retained 80% of its fatigue strength, and Nylon 6 retained 62%, while polyester cords broke before removal from the composite. The degradation of polyester was linked to a reduction in intrinsic viscosity over time and weak adhesion to the matrix.

Viscose is frequently employed in the construction of radial ply tire casings due to its adequate tensile strength, good adhesion to rubber compounds, and ability to maintain dimensional stability [82]. While not as prevalent as synthetic fibers, viscose presents a more sustainable option due to its biodegradability and sourcing from renewable resources. However, it is essential to consider its limitations in terms of durability, resistance to moisture and low wet strength compared to synthetic alternatives like polyester and nylon [83]. In recent years, there has been a shift towards using alternative fibers like lyocell in tire manufacturing. Lyocell, another form of cellulose fiber, provides higher wet tenacity and better environmental sustainability compared to traditional viscose rayon. This transition aims to address some of the limitations associated with viscose rayon, offering improved performance and eco-friendliness in tire production [24].

Aramid fibers, such as Kevlar, are utilized in high-performance applications due to their very high modulus. Carbon fibers are being increasingly utilized as reinforcing materials in many applications [84]. Carbon fibers offer the potential to enhance tire performance by increasing strength and reducing weight, leading to improved fuel efficiency and handling. However, the high cost of carbon fibers and the challenges associated with their dispersion and bonding in rubber compounds have limited their widespread adoption [85]. Currently, carbon fibers are more commonly found in high-performance tires for racing and other specialized applications, where the performance benefits justify the increased cost [86].

The utilization of these textile and rubber materials enables tire makers to enhance multiple performance attributes. Several tire producers employ reinforcing materials like chafer strips and bead wraps to enhance tire performance and durability, while simultaneously reducing overall weight. Chafer fabrics typically consist of woven polyester or Nylon 6,6 materials that have been coated with an adhesive chemical, such as resorcinol formaldehyde latex (RFL) [87]. Moreover, the increasing need for environmentally friendly renewable energy sources has sparked a revolution in the tire industry, focusing on the development of tire materials that are eco-friendly, lightweight, and long-lasting.

Figure 7. Typical composite structure of tire and different layers [88].

Figure 7. Typical composite structure of tire and different layers [88].

In addition to textile and metallic wire reinforcements, tires primarily use various rubber materials such as natural rubber, SBR, polybutadiene rubber, and isoprene rubber, often combined with reinforcing fillers like silica or carbon black to enhance durability, flexibility, and performance under cyclic loading conditions. Rubber resilience directly influences the ability of tires to absorb shocks, maintain its shape under stress, and resist deformation. High resilience ensures better energy dissipation during rolling, reducing heat buildup and enhancing wear resistance. This contributes to improved durability, fuel efficiency, and overall performance.

7.2. Conveyor Belts

Another critical industrial application of textile–rubber composites is in conveyor belts. Conveyor belts are widely employed in several industries to facilitate the movement of commodities between different locations. Their applications range widely from transporting little goods over short distances, such as at supermarket checkouts, to transporting large quantities of materials over long distances, as seen in quarrying and mining operations [89]. Choosing the appropriate belt conveyor types helps ensure optimal operational safety, increased labor productivity, minimal environmental effect, and streamlined operation and maintenance [90]. These essential components of material handling systems benefit greatly from the combination of rubber’s flexibility and textiles’ strength which resulted in high load-carrying capacity, excellent resistance to impact and tearing, flexibility to conform to various pulley configurations, and reduced noise and vibration during operation.

The efficiency of conveyor belts is significantly influenced by the choice of materials and the construction techniques employed, particularly when considering the distance materials need to be conveyed. For short-distance conveying, where flexibility and ease of installation are paramount, belts made from lighter materials like rubber reinforced with woven textiles such as cotton or nylon or their blends are often preferred [91]. These materials offer adequate strength and flexibility for navigating bends and inclines typical in shorter systems, such as those found in manufacturing plants or distribution centers. The construction usually involves a multi-ply design for enhanced tear resistance. However, for long-distance conveying systems, such as those used in mining or large-scale material handling, higher strength and durability are critical. In these scenarios, belts constructed from high-tensile synthetic textiles like polyester or aramid fibers, combined with specialized rubber compounds, are more suitable [92]. These materials provide the necessary load-bearing capacity and resistance to abrasion and environmental degradation over extended distances. Steel cable reinforcement may also be incorporated for extremely long and heavy-duty applications. The construction often involves advanced splicing techniques to ensure seamless and robust joints capable of withstanding continuous stress. Furthermore, the idler design and belt tensioning systems are optimized to minimize energy consumption and reduce wear over long distances [93].

Materials for Conveyor Belts

In the early stages, cotton was the predominant material utilized for the manufacturing of conveyor belts. Cotton exhibits excellent mechanical adherence and provides effective high temperature protection without undergoing melting. Subsequently, rayon supplanted cotton. Later, man-made synthetic fibers, primarily polyester, polyamide, and aramids captured the market of conveyer belt requiring higher durability and resistance to degradation due to the susceptibility of cotton and rayon to rot, mildew, and comparatively lower tensile strength.

The tensile strength and dimensional stability of conveyor belts are significantly influenced by the mechanical properties of their reinforcing textile fibers: polyester offers high modulus and resistance to stretching, enhancing belt stability; polyamide provides excellent elasticity and fatigue resistance, contributing to durability; and aramid fibers, known for their exceptional strength-to-weight ratio and thermal stability, impart superior tensile strength and resistance to deformation, thereby improving overall belt performance and longevity [94,95].

The majority of conveyor belts are manufactured using a multi-ply construction. The fabric weaves which are frequently utilized in conveyor belts are plain weave, 2 × 1 Matt or oxford weave, 2 × 2 twill, 2 × 2 broken twill or crowfoot and leno [89]. Though the development of textile–rubber composite conveyor belts stated utilizing natural rubbers, currently, several types of synthetic rubbers are used. The textile reinforcement provides the necessary tensile strength and dimensional stability, while the rubber coating offers excellent abrasion resistance and load-bearing capacity.

7.3. Defense Products

The defense industry also leverages the unique properties of textile–rubber composites for various applications. These materials are used in the production of protective gear, inflatable structures, and specialized equipment [96]. The combination of rubber’s elasticity and textiles’ strength results in products that offer superior protection and functionality. Some examples of defense applications have been discussed below.

7.3.1. Bulletproof Vests with Rubber-Coated Textile Layers

Textile–rubber composites are used in bulletproof vests to enhance impact absorption and improve ballistic performance. Key points include:

• Material composition: Rubberized coir combined with resin and coconut fiber has been studied as a cost-effective alternative to Kevlar [97]. Moreover, as a natural fiber-based composite, rubberized coir is biodegradable and less harmful to the environment compared to synthetic fibers like Kevlar. While it is not suitable for high-velocity rounds, rubberized coir composites can provide adequate protection against lower-caliber bullets or blunt impacts. The firing test results indicated that the 40% mixture variation 1-ply panels were able to withstand the rate of bullet rotation due to the density and strength of the resin-coconut fiber mixture. The hardness test revealed a peak average of 22.86 BHN (Brinell Hardness Number) at a 40% mixed variation, while the Charpy impact test showed a maximum average of 0.087 J/mm².
• Impact resistance: Kevlar/rubber composites have demonstrated improved ballistic performance due to the rubber matrix’s ability to absorb energy and maintain flexibility. In particular, high hardness rubber matrices offer higher energy absorption capacities compared to low hardness matrices impact [98].
• Enhanced properties: The incorporation of shear-thickening gels and nano-SiO₂ in Kevlar fabric composites has led to improved anti-impact performance, fire resistance, and multifunctional capabilities such as strain sensing and electro-heating [99]

7.3.2. Inflatable Boats and Rafts with High Puncture Resistance

Textile–rubber composites are also utilized in the construction of inflatable boats and rafts to provide high puncture resistance and durability. Key aspects include the following.

• Material durability: Nylon textile-reinforced natural rubber composites have been shown to strengthen the rubber material, making it suitable for applications requiring high durability and puncture resistance, such as car tires and potentially inflatable boats and kayaks [100]. Nylon/NR composites are used in inflatable boats due to their flexibility and airtightness. Under high pressure, nylon reinforcement provides structural support, preventing excessive deformation. However, the composites exhibit varying performance under extreme conditions, influenced by temperature and pressure. At elevated temperatures, such as 120 °C, these composites experience reduced fatigue life due to interfacial debonding and matrix cracks, compromising their durability. Conversely, at lower temperatures like −20 °C, they demonstrate enhanced fatigue resistance, attributed to slower crack propagation [101]. Regarding high-pressure scenarios, while specific studies on inflatable boats and kayaks are limited, the general mechanical reinforcement provided by nylon fabric enhances the tensile strength of natural rubber, suggesting improved performance under pressurized conditions [100]. However, prolonged exposure to extreme temperatures can degrade mechanical properties due to chemical and physical changes in the rubber matrix. Therefore, in applications like inflatable boats and kayaks, these composites offer benefits in strength and flexibility but require careful consideration of environmental conditions to maintain performance and longevity.
• Resistance to environmental factors: The combination of rubber and textile materials offers enhanced resistance to environmental factors like UV radiation, saltwater, and abrasion, which are critical for marine applications [102].

7.3.3. Chemical and Biological Protective Suits with Improved Barrier Properties

Textile–rubber composites are employed in protective suits designed to offer superior barrier properties against chemical and biological hazards. Key features include the following.

• Barrier properties: The rubber matrix in these composites provides an effective barrier against chemical and biological agents, while textile reinforcement ensures strength and flexibility.
• Enhanced protection: The use of high-performance fabrics such as Kevlar, combined with rubber matrices, can enhance the protective capabilities of these suits by providing additional impact resistance and durability [99,100].

7.4. Aircraft Structures

Fabric rubber composites play a crucial role in aircraft door structures, operating under extreme conditions ranging from −55 °C to 85 °C and pressure differentials up to 60 kPa. These materials must withstand 160,000 door cycles, necessitating focus on compression resilience, dynamic friction, sealing performance, and durability during design. Wear resistance is a critical property for materials used in aircraft doors due to the high frequency of use and exposure to environmental factors. Aircraft doors undergo repeated opening and closing cycles, leading to frictional wear on the door components, including seals, hinges, and locking mechanisms [103]. The wear of these components can compromise the structural integrity, sealing performance, and operational reliability of the door [104]. Therefore, materials with high wear resistance are essential to ensure the longevity, safety, and optimal performance of aircraft doors.

Dong et al. [105] developed textile–rubber composites based on two primary textile structures—textile fabrics and reticulated fabrics. Textile fabrics, being denser, reduce sliding friction and provide wear resistance. Reticulated fabrics, with their sparser structure, offer reinforcement. When combined with rubber, these form anisotropic composites with distinct mechanical properties. The anisotropic nature arises from the oriented arrangement of the reinforcing textile fibers within the rubber matrix, which leads to directional dependence in mechanical properties. However, the hyperviscoelastic nature of rubber exhibiting large deformation, nonlinearity, temperature sensitivity, and stress softening, complicates the characterization of these composites.

7.4.1. Effects of Hyperviscoelasticity on Fabric–Rubber Composites

Large Deformation and Nonlinearity

The hyperelastic behavior of rubber under large strains complicates the prediction of stress–strain responses. Micromechanical modeling approaches, such as those described by Zheng et al. [106], provide a framework for understanding the stress–strain behavior of textile elastomeric composites by combining fiber and matrix properties. These models predict stress distribution and failure criteria under complex loading conditions. Moreover, nonlinear constitutive models are essential for capturing the mechanical response of rubber composites. For instance, numerical methods like topology optimization have been used to design hyperelastic structures that undergo large deformations, enabling better characterization of tensile properties [107].

Temperature Sensitivity

Rubber composites exhibit significant changes in mechanical properties with temperature variations. Studies have shown that vulcanization temperature affects tensile strength and compressive properties. For example, silicone rubber composites demonstrate increased tensile strength up to an optimal vulcanization temperature, after which it declines due to material degradation [108]. Thermal aging also impacts the cross-linking density and mechanical properties of rubber. Phenomenological models based on Arrhenius equations have been proposed to predict these changes accurately [109].

Stress Softening (Mullins Effect)

The Mullins effect complicates the durability assessment of rubber composites under cyclic loading. Research highlights that stress softening must be incorporated into constitutive models to predict fatigue life and performance under repeated strain cycles [110].

Research methods from the broader field of composite materials provide valuable insights for evaluating and optimizing the mechanical properties of fabric rubber composites. Figure 8 shows a schematic design of different textile–rubber composite structures.

In summary, textile–rubber-based materials play a crucial role in various industrial applications, offering unique combinations of properties that are often superior to conventional materials. As sustainability becomes a key focus in manufacturing, the development of these composites using recycled materials presents an opportunity for more environmentally friendly industrial solutions.

8. Advantages of Textile–Rubber Composites Materials

Textile–rubber-based materials offer several advantages over conventional materials in industrial applications.

(i)

Versatility: These composites can be engineered to meet specific performance requirements by adjusting the textile reinforcement and rubber compound [88,111,112,113]. Wang et al. [112] evaluated the properties of different fiber-based textile fabrics and their composites with silicone rubber for applications in soft robotics. Silicon rubber has high elongation at break and possesses good resistance to temperature, oil, acid and alkali, but shows poor performance in terms of tensile strength, tear strength, and puncture resistance. These deficiencies of silicon rubber can be improved significantly by making fiber/silicon rubber composites, as summarized in

Table 5. Fabric characteristics made of different fibers and the mechanical properties of their composites with silicone rubber [60,113].

Quantitative and Qualitative Measures of Fabric Characteristics
Fabric	Composite Fiber Type	Breaking Strength (N)	Elongation at Break (%)	Thread Count (cm)	Denier (mg/m)	Tenacity (N·m/g)	Permeability	Absorbency
Polyester	Synthetic	463.92	40.4	23	3.38	80.3	Low	Low
Silk	Natural	315.89	14.67	40	0.74	83.2	Low	Low
Nylon	Synthetic	280.83	40.2	33	1.42	56.3	Median	Low
Polyester/cotton	Synthetic-natural blend	221.69	22.87	28	1.97	44.4	Median	Median
Cotton	Natural	135.62	21.47	24	2.32	31.4	High	High
Rayon/spandex	Synthetic blend	79.64	193.39	27	4.52	7.49	Median	High
Fabric/Rubber Composite Mechanical Properties
	Tensile strength (MPa)		Elongation at break (%) mean	Toughness (MPa)	Tear strength (kN/m)		Puncture resistance (N)
Embedded fabric	Mean	Relative%			Mean	Relative%	Mean	Relative%
None (unreinforced)	3.87	—	194	7.51	4.54	—	66.5	—
Polyester	14.9	386	34	5.02	25.6	564	315	474
Nylon	9.21	238	59	5.39	19.7	352	214	322
Polyester/cotton	8.86	229	21	1.87	11.9	262	146	219
Silk	6.29	163	21	1.3	6.01	132	92.8	140
Rayon/spandex	3.59	92.8	117	4.2	16.2	356	103	155
Cotton	2.67	69.0	28	0.75	6.23	137	77.7	117

. The findings of this research indicate that incorporating strong fabrics into composites significantly enhances their mechanical strength and durability, making them ideal for applications such as pneumatic soft robotics. Conversely, elastic fabrics preserve the flexibility of materials while improving tear resistance, which makes them particularly well-suited for use in robotic skins or soft strain sensors.

(ii)

Durability: The combination of textile strength and rubber resilience results in products with extended service life, reducing replacement frequency and associated costs [96]. For example, long-lasting conveyer belts which are used in mining and industrial processes are designed to withstand heavy loads and abrasion [89,90]. In an interesting study, Andrejiova et al. [113] evaluated the impact resistance of rubber–textile and steel–cord conveyor belts (Figure 9a,b). It analyses variables such as hammer weight, fall height, belt strength, and belt type, providing a comprehensive assessment of how these factors influence belt durability. The extent of damage was assessed through visual inspection following testing. Damage severity was categorized into two levels: minor (Damage 0 and 1), which would not require belt removal, and major (Damage 2 and 3), which would necessitate taking the belt out of service—representative damage examples are shown in Figure 9c. The energy absorption was evaluated using the rebound height after initial impact. Figure 9d illustrates the time-dependent rebound profile for a 90 kg hammer impacting rubber–textile (P2500, P1250, Continental Matador Rubber, Puchov, Slovakia) and steel–cord (ST2500, ST1250, Continental Matador Rubber, Puchov, Slovakia) conveyor belts. At a lower strength of 1250 N∙mm⁻¹, both rubber textile and steel cord conveyor belts absorb more impact energy compared to 2500 N∙mm⁻¹. Specifically, rubber belts absorb 60–69% (vs. 40–51%), while steel cord belts absorb 73–84% (vs. 70–84%) of the impact energy. Consequently, for rubber textile conveyor belts, no instances of severe damage (Damage 2) were recorded across all tested impact heights and weights using a spherical impactor. In contrast, steel cord conveyor belts had 44 samples (70.96%) with no damage, 9 samples (14.52%) with moderate damage, and 9 samples (14.52%) with severe damage (Figure 9e). Notably, the ST1250 belt suffered significant damage, including puncture, when impacted from 1.8 m. This study provides valuable insights into the impact resistance of different conveyor belt types, highlighting how belt strength and construction influence energy absorption and damage severity—critical factors for improving belt durability and operational safety in material handling systems.

(iii)

Weight reduction: Textile–rubber composites often provide superior strength-to-weight ratios compared to metal alternatives, leading to energy savings in transportation and handling. Two potential examples can be lightweight vehicle components such as door panels or suspension systems that improve fuel efficiency and lightweight yet durable bike tires and protective gear [114].

(iv)

Corrosion resistance: Unlike metal components, textile–rubber materials are inherently resistant to corrosion, making them ideal for use in harsh environments [96]. Example includes marine applications such as inflatable boats and rafts that resist saltwater corrosion [115] and rubber-lined tanks and pipes used in corrosive chemical processing environments [116].

(v)

Vibration damping: The viscoelastic properties of rubber combined with textile reinforcement offer excellent vibration and noise reduction capabilities. For example, rubber-based composite materials and sandwich structures are utilized in providing vibration damping features in vehicle structures [117,118].

(vi)

Customization: These materials can be tailored to specific applications by selecting appropriate textile fibers (e.g., cotton, nylon, polyester, Kevlar) and rubber compounds (e.g., nitrile, chloroprene, silicone, natural) [96]. For example, customized kevlar–silicone rubber composites are used in lightweight yet durable aircraft components such as inflatable evacuation slides and protective covers for sensitive equipment. Kevlar provides high tensile strength and impact resistance, while silicone ensures flexibility and temperature tolerance [119].

(vii)

Sustainability: With growing emphasis on environmental concerns, the use of recycled rubber and textiles in composite materials is becoming increasingly important [120]. Examples include circular economy initiatives like recycled conveyor belts repurposed into eco-friendly flooring materials [121] and sustainable footwear made from recycled rubber soles combined with textile uppers are becoming important in footwear fashion industry [122].

9. Recycling and Upcycling Initiatives

The textile industry has been under increasing pressure to adopt sustainable practices due to its significant environmental impact. Recycling and upcycling initiatives are pivotal in reducing waste and promoting sustainability. Moreover, studies have highlighted that recycling textiles can significantly reduce CO₂ emissions and decrease the demand for virgin materials, thus mitigating the environmental impact of the textile industry [123]. This section highlights the technologies applicable to recycling and upcycling textile and rubber-based materials, focusing on industrial applications and recent advancements.

9.1. Textile Recycling

Textile recycling involves converting waste textiles into reusable materials.

9.1.1. Technologies for Textile Recycling

Textile recycling technologies are primarily divided into mechanical and chemical processes:

(i)

Mechanical recycling: This involves physically deconstructing fibers through shredding or crushing. It is effective for single-material textiles, such as 100% cotton, but results in weaker fibers suitable for low-quality applications like insulation or stuffing. When applied to blended materials or textile–rubber composites, the process is significantly less effective. The presence of vulcanized rubber disrupts fiber separation and contaminates the recycled stream, often leading to lower structural integrity and poor bonding characteristics in the output. Moreover, rubber components are thermoset and non-meltable, which limits reprocessing potential. These limitations reduce the quality and feasibility of recycled products derived from such composites [124,125,126].

(ii)

Chemical recycling: This method breaks down textiles into their molecular components using chemical solutions, allowing the production of fibers of similar quality to new ones. Chemical recycling is promising for mixed fibers, with novel approaches using enzymes to separate blended materials like cotton and polyester. However, these technologies are not yet widely available and are typically limited to small-scale operations [126,127].

(iii)

Thermo-chemical: Thermo-chemical recycling uses gasification to produce syngas from polymers, applicable to all fiber types but not a closed-loop solution.

(iv)

Bio recycling: Bio-recycling employs enzymatic hydrolysis to decompose composite textile materials into reusable components, such as recovering polyester fibers and converting cotton into glucose for bioethanol production. This method has shown promise in processing cotton–polyester blends, facilitating the separation and reuse of constituent materials [127,128]. However, its application in rubber-containing composites remains underexplored, indicating a need for further research to assess feasibility and develop effective methodologies for such materials.

9.1.2. Few Examples of Textile Recycling and Upcycling Initiatives

One prominent initiative is SuperCircle, a tech and reverse logistics company that focuses on textile-to-textile recycling by connecting fashion brands to post-consumer textile waste and the necessary recycling infrastructure. SuperCircle facilitates both fiber-to-fiber (F2F) and componentry-to-componentry (C2C) recycling, which are central to achieving circularity. To enable F2F recycling, SuperCircle addresses major industry challenges such as the cultivation of clean material feeds—ensuring garments are sorted and aggregated by fiber type—and manages critical preprocessing steps like trimming, shredding, and baling to prepare garments for recycling. Additionally, they help brands design recyclable garments and implement take-back programs, all while navigating the limitations of current material compositions. Where ideal circular solutions are not feasible, they also deploy open-loop alternatives like downcycling and energy recovery, making SuperCircle’s approach both pragmatic and impactful. As mentioned, a key element of SuperCircle’s strategy involves the implementation of robust take-back programs. These programs are designed not only to collect used garments but also to ensure clean material streams through proper sorting and aggregation. SuperCircle supports brands in launching take-back schemes by emphasizing ease-of-participation for consumers and offering education and incentives to encourage returns. Such programs are necessary because textiles are not municipally recyclable, and without them, viable recycling channels cannot be established. Ultimately, these efforts contribute significantly to building a reliable supply of recyclable feedstock and reducing dependency on landfill or low-value waste management solutions [127]. Another significant initiative is the PESCO-UP project, led by the VTT Technical Research Centre of Finland. This project aims to enhance the textile recycling value chain by developing digitalized material identification, data sharing, and advanced sorting systems. The project targets up to 90% material processing efficiency through innovative chemical and mechanical separation methods [128].

Unlike conventional recycling, which typically breaks down materials into their base components with potential degradation of quality, upcycling aims to convert waste materials into products of higher value with retained or enhanced utility. Textile Recyclers Australia (TRA) exemplifies this through a process where worn garments are sorted, shredded into fibers, spun into recycled yarn, and woven into new textiles. This approach helps retain more of the integrity of materials while reducing landfill waste. The upcycled yarn is used in new apparel, creating a sustainable resource loop. While the benefits include reduced environmental impact and extended material life cycles, the challenges include fiber degradation during shredding and the need for consistent input quality to meet commercial standards [129].

Fast Retailing, the parent company of UNIQLO, has implemented comprehensive initiatives to recycle collected clothes into new garments. For example, they extract down and feathers from used jackets using a proprietary recycling technology developed in collaboration with Toray Industries. This process enables the production of items like the recycled hybrid down jacket, which utilizes 100% recycled materials. Additionally, Fast Retailing supports broader upcycling through in-store repair and remake services in cities like Berlin, New York, and London, where used clothing is creatively transformed via embroidery, patchwork, and traditional techniques such as sashiko. Non-recyclable textiles are repurposed for insulation (e.g., in building walls) and soundproofing applications (e.g., in electric vehicles). These efforts exemplify a scalable model for circular fashion and sustainable industrial applications by reducing textile waste, lowering carbon emissions, and conserving energy. This approach demonstrates the potential for upcycling in creating sustainable industrial applications [130].

9.1.3. Challenges in Textile Recycling and Upcycling

Despite technological advancements, several challenges hinder the widespread adoption of textile recycling and upcycling initiatives.

• Material complexity: The presence of blended materials containing different fibers (for example, polyester/cotton, cotton/lycra, nylon/lycra, wool/nylon, wool/polyester, acrylic/cotton, etc.), finish and coatings, and non-textile components like zippers and buttons complicate the recycling process. These elements often need to be removed manually, increasing labor and costs [125].
• Infrastructure limitations: Current recycling infrastructure is not equipped to handle the high volume of textile waste. The integration of textile collection with existing waste management systems is complex and requires significant logistical planning [125].
• Cost and environmental considerations: Recycled textiles are often more expensive to produce than new materials. Additionally, some recycling technologies are resource-intensive, consuming large amounts of energy and water [125].
• Consumer awareness and participation: Educating consumers about proper disposal and recycling practices is crucial for reducing textile waste. However, many consumers are unaware of how to recycle textiles effectively [131].

9.2. Rubber-Based Material Recycling

Rubber recycling is a crucial component of sustainable waste management, particularly given the environmental challenges posed by rubber waste, such as used tires. The recycling of rubber materials not only helps in reducing landfill waste but also contributes to the conservation of natural resources by providing an alternative to virgin rubber production.

9.2.1. Technologies for Rubber Recycling

Among different rubber recycling technologies most important technologies are as described below.

(i)

Devulcanization: This process involves breaking the sulfur cross-links in vulcanized rubber (as shown in Figure 10), allowing it to be reprocessed. Devulcanization can be achieved through various methods, including thermal, mechanical, chemical, and microbial processes. For example, the use of supercritical carbon dioxide combined with diphenyl disulfide has shown effectiveness in devulcanizing natural rubber industry waste [62,132].

(ii)

Thermomechanical processes: These involve the use of mechanical forces and heat to reclaim rubber. A co-rotating twin-screw extruder is an example of equipment used for the effective thermomechanical devulcanization of ground tire rubber [132]. This method allows for the production of thermoplastic vulcanizates, which are blends of rubber and thermoplastics.

(iii)

Microwave and ultrasonic methods: These advanced techniques apply energy to selectively break cross-links in rubber. Microwave devulcanization, for instance, has been explored for its ability to efficiently reclaim rubber without significant degradation of its properties [133,134].

(iv)

Chemical recycling: This involves using chemicals to break down rubber into its constituent monomers or other useful compounds. This method can be tailored to target specific types of rubber, such as styrene-butadiene rubber, using specific reagents like zinc (II) dithiocarbimate derivatives [133].

(v)

Pyrolysis: This process involves the thermal decomposition of rubber waste in the absence of oxygen, producing oil, gas, and char. Pyrolysis is a versatile method that can handle various types of rubber waste, including tires, and convert them into valuable by-products [133].

Generally, rubbers are recovered from end-of-life tires (ELTs) in form of crumb rubbers using any one of these methods such as ambient grinding, cryogenic grinding, wet grinding and ozone cracking [132].

9.2.2. Mechanical Properties of Recycled Rubber

The formation of conjugated double bonds (Figure 10) during reversion processes is known to adversely affect the mechanical properties of rubber materials. Consequently, sintered rubber exhibits notably inferior mechanical characteristics compared to composites fabricated from virgin rubber. This phenomenon is attributed to the structural changes that occur during the sintering process, which alter the molecular arrangement and cross-linking density of the rubber matrix. The mechanical properties of sintered rubber products are primarily determined by the interplay of processing temperature, sintering duration, rubber granulate (RG) composition, and the grain size distribution. These factors collectively influence the structural integrity and performance characteristics of the vulcanized elastomers.

The incorporation of RGs into composite materials generally results in a notable decline in mechanical properties as the RG content increases. However, an exception is observed in the elongation at break, which exhibits a modest increase from approximately 320 to 400% as the RG content rises from 10 to 50 parts per hundred rubbers (phr) [61]. This overall deterioration in mechanical performance can be attributed to the progressive reduction in cross-link density within the vulcanizates as the RG content increases. The diminishing cross-link density is directly correlated with the higher proportion of RG filler in the composite structure. Interestingly, research has shown that the mechanical properties of sintered materials derived from natural rubber granulates can be enhanced through the addition of low molecular weight organic acids. Compounds such as salicylic acid, benzoic acid, maleic acid/anhydride, phthalic anhydride, and phthalimide have demonstrated efficacy in improving the mechanical characteristics of these sinters [134].

9.2.3. Advances in Rubber Recycling and Upcycling with Potential Applications

Rubber waste can be recycled and upcycled into products with added value, such as carbon nanotubes, value-added fuels, construction additive materials (with asphalt), and thermoplastic elastomers (TPE). One way to produce value-added products is through upcycling scrap rubber into thermoplastic epoxy (TPE). However, the mechanical performance of these additives is poor due to their immiscibility and incompatibility with rubber-based polymers in polymer matrixes [135]. Therefore, recent advancements in rubber recycling have focused on improving the efficiency and quality of reclaimed rubber. For instance, EcoTech Recycling has developed a patented technology that transforms used tires into synthetic rubber without the use of oils or chemicals, significantly reducing energy consumption and environmental impact. This patented technology [136] introduced a method for reprocessing vulcanized rubber waste into reusable rubber material. This process involves treating rubber particles with a specific acid mixture to break down the sulfur cross-links characteristic of vulcanized rubber, effectively devulcanizing the material, but preserving the integrity of material for reuse. The resulting rubber can then be revulcanized and utilized in manufacturing new rubber products, thereby promoting a closed-loop recycling system. Traditional rubber production from raw materials is energy intensive. Recycling rubber through this devulcanization process requires less energy, leading to overall energy savings in rubber manufacturing which is directly correlated with reduced greenhouse gas like CO₂ emissions. Additionally, diverting rubber waste from landfills minimizes methane emissions associated with rubber decomposition, thus reducing landfill dependency. This approach not only closes the loop on tire recycling but also produces high-quality rubber suitable for a wide range of applications. Conversely, the upcycling of waste rubber into carbon nanotubes and value-added fuels demonstrated a viable remediation technique for a prosperous management of rubber waste, while another upcycling method involved using rubber waste in building materials [135].

The perception RGs in the tire recycling industry has evolved significantly, transitioning from a low-cost filler to a valuable component in sustainable rubber composite manufacturing. RGs now find widespread application in diverse sectors, including molded and extruded products, landscaping, animal husbandry, recreational facilities, sports surfaces, and automotive components. However, the utilization of RGs in high-performance applications, such as new tire production, remains limited due to quality and strength constraints. Consequently, RG-based composites are predominantly employed in the fabrication of less demanding products where mechanical strength is not a critical factor. These applications include flooring materials, seals, automotive accessories, and footwear components. Additionally, sintered RGs have demonstrated potential in the production of various items, including washers, roofing materials, insulation boards, and solid tires, further expanding their utility in sustainable manufacturing processes [137]. Figure 11 represents the rubber recycling pathways and applications of ground tire rubber (GTR), also highlights the optimal waste management approach, producing secondary materials with enhanced properties relative to the original GTR.

9.2.4. Challenges in Rubber Recycling

Despite technological advancements, several challenges persist in rubber recycling.

• Complexity of rubber composites: The presence of various additives and fillers in rubber products complicates the recycling process, as these components must be separated or accounted for during recycling. Passenger and truck tires differ in metal and textile content by approximately 10 wt%, with truck tires containing more steel for enhanced strength and passenger tires incorporating more textiles for weight reduction [138]. Recycling processes typically involve labor intensive downsizing and sorting to separate these components.
• Difficulty in devulcanization: Vulcanized rubber has a stable three-dimensional cross-linked structure, making devulcanization technically challenging. Most chemical and thermal devulcanization techniques are energy-intensive and may degrade rubber properties. Even partial devulcanization often leads to material with inferior mechanical properties compared to virgin rubber, limiting its use in high-performance applications.
• Quality of reclaimed rubber: The quality of recycled rubber is significantly influenced by impurities and structural defects. Efficient separation of non-rubber components from ELTs is crucial but resource-intensive, often resulting in inferior properties compared to virgin rubber due to batch inconsistencies [132]. Reclaimed rubber generally exhibits inferior mechanical properties compared to virgin rubber, limiting its applications. Continuous efforts are needed to improve the quality of recycled rubber to expand its usability [133].
• Economic viability: The cost of recycling rubber can be high, particularly for advanced processes like pyrolysis and devulcanization. Developing cost-effective methods is crucial for the widespread adoption of rubber recycling technologies. Moreover, the economic feasibility of these methods is further hampered by fluctuating oil prices and limited demand for recycled rubber, especially in high-performance industries.
• Regulatory and market barriers: The lack of standardized regulations and market acceptance for recycled rubber products can hinder the growth of the recycling industry. Increasing awareness and creating incentives for using recycled materials are necessary to overcome these barriers.

Recycling and upcycling initiatives in the textile and rubber-based materials sectors are crucial for promoting sustainability and reducing environmental impact. Through innovative technologies and collaborative efforts, the industry can move towards a more circular economy, where waste is minimized, and materials are continuously reused. These initiatives not only contribute to environmental conservation but also offer economic opportunities (see Figure 12) by creating new markets for recycled and upcycled products.

10. Conclusions and Future Perspectives

This review has provided a comprehensive overview of rubber-based sustainable textiles for industrial applications, highlighting the intersection of sustainable textile manufacturing and the rubber industry. Eco-friendly fiber and material selection, sustainable elastomer sources including natural and synthetic rubbers, and the use of sustainable additives such as fillers, plasticizers, antioxidants, and vulcanization accelerators have been explored. The review delved into the composition and manufacturing of textile–rubber composite materials, emphasizing their wide-ranging industrial applications. From tires and conveyor belts to defense products and aircraft structures, these composites demonstrate versatility and enhanced performance characteristics. Moreover, textile and rubber recycling technologies have made significant strides in recent years, offering promising solutions for managing textile and rubber waste sustainably. However, challenges such as material complexity, quality of reclaimed rubber, and economic viability remain. Continued research and innovation are essential to address these challenges and fully realize the potential of rubber recycling in contributing to a circular economy. Therefore, the advantages of textile–rubber composites and their potential to address sustainability challenges in various sectors have been discussed. The review also focused on recycling and upcycling initiatives for both textiles and rubber-based materials, outlining current technologies, successful examples, and persistent challenges.

As the industry moves towards more sustainable practices, the integration of eco-friendly materials, innovative manufacturing techniques, and efficient recycling processes will be crucial. The development of rubber-based sustainable textiles represents a significant step towards reducing environmental impact while meeting the demanding requirements of industrial applications. Future research and development in this field should focus on overcoming the challenges in recycling, improving the performance of sustainable materials, and expanding the range of applications for these eco-friendly composites. By continuing to innovate in this area, the textile and rubber industries can contribute significantly to a more sustainable and circular economy. Eco-friendly textile–rubber composites incorporating organic fillers in different natural rubbers may offer improved environmental sustainability and enhanced biodegradability. These ‘green’ composites aim to reduce or eliminate the use of petroleum-based, non-renewable mineral fillers. Current research focuses on enhancing the mechanical properties of these composites through filler modification, adhesion promoters, and additives. Improving interfacial adhesion between natural fibers and the rubber matrix remains crucial for optimizing overall performance. Ongoing research addresses challenges such as insufficient toughness, moisture absorption, and limited long-term stability in outdoor applications. Future efforts will prioritize developing composites resistant to various weathering conditions, including humidity, temperature fluctuations, and UV radiation, to ensure the prolonged service life of these environmentally friendly textile–rubber composites.