Next Article in Journal
Quantitative Evaluation of Aggregate Gradation Based on Synergistic Mechanism of Geometric Characteristics, Size and Passing Rates
Next Article in Special Issue
Carvacrol-Containing Hemicellulose/Methylcellulose Plant-Based Coatings and Films: Evaluation of Antimicrobial Activity, Biodegradability, and Cytocompatibility
Previous Article in Journal
Effect of Diamond Content on Microstructure and Wear/Corrosion Resistance of CoCuNiTi + x Diamond (C) (x = 0, 0.5, and 1.0 wt.%) High-Entropy Alloy Coatings
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Coatings
Volume 16
Issue 3
10.3390/coatings16030289
coatings-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Review

From Plants to Performance: A Sustainable Approach to Fiber Reinforcement Using Biopolymers

by
Karine Sayuri Lima Miki
1,
Ytaiara Lima-Pereira
1,
Nelícia Nunes de Souza Muniz
2,3,
Willian Hermogenes Ferreira
4,
Orquidea Vasconcelos dos Santos
5 and
Barbara Elisabeth Teixeira-Costa
1,2,3,*
1
Graduate Program in Biotechnology (PPGBIOTEC), Federal University of Amazonas, Manaus 69080-900, AM, Brazil
2
Integrated Nutrition Center (CIAN), Department of Nutrition and Dietetics, Federal Fluminense University, Niteroi 24020-140, RJ, Brazil
3
Graduate Program in Food and Nutrition (PPGAN), Federal University of the State of Rio de Janeiro (UNIRIO), Rio de Janeiro 66075-110, RJ, Brazil
4
Institute of Macromolecules Professor Eloisa Mano, Federal University of Rio de Janeiro, Rio de Janeiro 21941-598, RJ, Brazil
5
Graduate Program in Food Science and Technology (PPGCTA), Federal University of Pará (UFPA), Belém 66075-110, PA, Brazil
*
Author to whom correspondence should be addressed.
Coatings 2026, 16(3), 289; https://doi.org/10.3390/coatings16030289
Submission received: 16 January 2026 / Revised: 8 February 2026 / Accepted: 25 February 2026 / Published: 27 February 2026
(This article belongs to the Special Issue Plant-Based Composite Films and Coatings: Green Techniques, Natural Products and Sustainability to a Healthier Future)
Browse Figures
Versions Notes

Abstract

This review highlights recent progress in the sustainable extraction, production and application of plant fiber-reinforced biopolymer composites. The review mainly focuses on properties of these materials—mechanical, thermal, and interfacial—and explores how factors such as fiber type, extraction methods, and surface treatments (e.g., enzymatic retting, deep eutectic solvents, steam explosion) affect fiber morphology and bonding with the polymer matrix. The work also discusses strategies to select and modify biopolymer matrices (e.g., PLA, PHA) for better compatibility, recyclability, and long-term performance, addressing challenges like fire resistance and environmental impact. Special attention is given to cellulose surface modification, which improves wettability and interfacial adhesion, while highlighting alternatives to conventional chemical treatments due to cellulose’s high crystallinity and strong hydrogen bonding. Despite advances in surface treatments and manufacturing, persistent challenges include moisture sensitivity, processing reproducibility, and standardization. Future research should prioritize application-tailored extraction, scalable eco-friendly modifications, and standardized testing to optimize durability and circular economy alignment. These fiber-reinforced biopolymer composites offer a viable path to fossil-free, high-performance materials. Overall, this review provides a comprehensive perspective that bridges sustainability and industrial applicability, offering practical guidance for developing high-performance, eco-friendly composites.

1. Introduction

The increasing global demand for sustainable materials has driven significant interest in the development of biopolymer-based composites reinforced with natural plant fibers. Natural fibers, derived from abundant renewable resources, offer an eco-friendly and effective alternative to synthetic fibers traditionally used in composite materials, especially in construction and engineering applications [1,2]. Their integration into biopolymer matrices not only reduces the environmental trail associated with conventional composites but also influences the inherent mechanical, thermal, and biodegradable properties of both constituents [3].
Plant fibers such as hemp, flax, jute, cotton, milkweed, agave, bamboo, kenaf and others are valued for their high strength-to-weight ratios, biodegradability, and carbon sequestration capacity during growth, which collectively contribute to lowering greenhouse gas emissions throughout their lifecycle [4,5]. While the incorporation of plant fibers into biopolymer matrices has been widely investigated, most existing studies address fiber properties and matrix characteristics independently. As a result, the combined effects of fiber treatments, hybrid reinforcement strategies, and matrix selection on overall composite performance remain insufficiently explored. This review aims to fill this gap by critically evaluating recent advances in fiber-reinforced biopolymer composites, with particular emphasis on interfacial modification techniques, mechanical improvements and eco-friendly strategies.
Biopolymers, including polylactic acid (PLA), polyhydroxyalkanoates (PHA), and other biodegradable polymers, provide a versatile and environmentally friendly matrix for incorporating these fibers [6]. Environmental concerns associated with petroleum-based polymers, making fiber-reinforced biopolymer composites particularly attractive for engineering and construction-related applications, as well as for selected automotive and consumer products where mechanical integrity and sustainability are required [6,7].
Recent advances in material characterization, hybrid reinforcement strategies, and processing technologies—such as improved extrusion and compounding methods—have improved the performance potential of fiber-reinforced biopolymer composites [4]. These developments support the use of such materials in both structural and semi-structural applications, aligning with global sustainability goals and circular economy principles. In this context, this review focuses on the utilization of plant-derived fibers in advanced biopolymer composites, with emphasis on interfacial modification, mechanical performance, and sustainable design strategies relevant to engineering and construction applications.

2. Biopolymers and Natural Fiber

Biopolymers are polymeric materials derived from renewable biological sources or produced through biological processes. In composite systems, biopolymers constitute the primary component and serve as the continuous matrix phase [8,9]. Natural fibers, by contrast, are fibrous materials obtained mainly from plant or animal sources. In composites, natural fibers represent the dispersed phase and are incorporated into the biopolymer matrix, where they act as reinforcement by enhancing mechanical and thermal properties [6,7,10]. Fibers from different sources have distinct properties and advantages. Jute, hemp, kenaf, and sisal are the main types of natural fibers, and they are mainly grown for their high fiber production [10].
Biopolymers are macromolecules produced by living organisms or synthesized by renewable monomers. They include polysaccharides such as cellulose, starch, and chitin; polyesters such as polylactic acid (PLA) and polyhydroxyalkanoates (PHAs); and proteins such as collagen and gelatin. Although biologically derived materials such as cellulose and natural rubber have been used for centuries, interest in biopolymers has intensified due to growing concerns about sustainability and the replacement of fossil-based polymers [7]. Currently, biopolymers are widely applied in biodegradable packaging, agriculture, tissue engineering, controlled drug delivery, and other emerging applications [11].
Natural biopolymers contribute significantly to the structural performance of composite materials due to their intrinsic mechanical properties and biodegradability. Molecular architecture, often characterized by strong, stiff chain-like structures and the ability to be chemically modified, enables the formulation of composites that achieve desirable balance between strength, toughness, and environmental sustainability [12]. When reinforced with natural plant fiber, biopolymers provide enhanced load transfer and improved mechanical stability, making them promising candidates for structural applications where high performance and eco-friendliness are required [13]. Furthermore, advances in crosslinking and chemical modification techniques have expanded the potential of biopolymers to meet specific mechanical demands, ensuring their continued development as viable sustainable alternatives in engineering and construction sectors [14].
Their properties depend directly on their chemical structure and bonds, crystallinity degree, and stereochemistry [15]. Currently, polylactic acid (PLA), PHAs, thermoplastic starch (TPS), chitin/chitosan, and cellulose derivatives are among the most studied and applied biopolymers. PLA stands out for its processability in conventional molding and 3D printing techniques, in addition to presenting good mechanical properties and transparency, being widely used in packaging and additive manufacturing [6,7]. PHAs, produced by microorganisms, have excellent biodegradability and biocompatibility, making them especially promising for medical applications such as sutures and drug delivery systems [11]. TPS is attractive because it is derived from abundant and low-cost sources, such as corn and cassava, although it requires modifications to overcome mechanical and water stability limitations [15]. Chitin and chitosan stand out for their antimicrobial properties and film-forming ability, expanding their use in the biomedical and active packaging fields [7]. Another widely used biopolymer is cellulose derivatives such as acetate and nanocellulose, which have high rigidity and reinforcement capacity, with growing interest in advanced papers and functional biocomposites [16].
Despite the versatility of these materials, the selection of a biopolymer matrix requires a critical evaluation of trade-offs between rigidity, toughness, processability, and cost. For instance, while PLA offers high stiffness and excellent processability comparably to polystyrene, its application is often limited by inherent brittleness and low thermal stability [6,7]. In contrast, PHAs provide superior biodegradability and biocompatibility suitable for medical uses, but their broader industrial adoption is hindered by high production costs and a narrow processing window [11]. Similarly, although TPS is derived from abundant, low-cost sources, its high hydrophilicity results in poor water resistance and mechanical variation, often necessitating blending or chemical modification [15].
Consequently, the choice of matrix must align with the specific performance requirements of the final application. Table 1 summarizes the key properties, limitations, and typical trade-offs for the most common biopolymer matrices discussed.
Natural fibers, in turn, are lignocellulosic materials extracted from different parts of plants, in addition to also being of animal and mineral origin [16]. Structurally, plant fibers are composed of semicrystalline cellulose microfibrils arranged in an amorphous matrix of hemicellulose, lignin, and pectin. Structurally, it is divided into four layers: the outermost middle lamella contains high amounts of pectin; the second layer is the primary cell wall, which is less rigid and allows for cell growth, and is composed mainly of cellulose, hemicellulose, and pectin. The third layer, known as the secondary cell wall, is thicker and more resistant due to its cellulose, pectin, and hemicellulose bonds and may contain lignin, making it the most organized and dense layer. The central layer is the lumen, through which nutrients and water flow, whose morphology defines fibers’ density, water absorption, and mechanical strength [17]. Different natural fibers are used, such as sisal, jute, hemp, flax, and bamboo, among others. These fibers have aroused great interest due to their high strength-to-weight ratio, low cost, abundance, and renewable nature, being applied in various sectors [16,18]. These natural reinforcement fibers predominantly exhibit filamentary morphology, as illustrated in Figure 1 for jute fiber.
The combination of biopolymers and natural fibers results in biocomposites with more attractive mechanical and environmental performance. Fiber incorporation can improve the modulus, strength, and thermal stability while reducing the use of fossil resources [15,18]. However, the difference in polarity between hydrophilic fibers and hydrophobic matrices, such as PLA, requires attention, as the necessary chemical treatments can increase roughness and promote chemical bonding, optimizing load transfer [15,19]. Recent studies demonstrate that variations in fiber volume fraction, orientation, and distribution directly influence the performance and durability of purchased composites [18,19].
There are already examples of the use of these fibers in industry, such as PLA or PLA/PHA reinforced with hemp, flax, or sisal fibers, used in interior automotive components such as door panels and dashboard supports, offering rigidity and lightness, in addition to reducing the vehicle’s carbon footprint [18,20]. In biomedical applications, combinations of chitosan and nanocellulose have shown promise for dressings, scaffolds, and controlled drug release, thanks to their biocompatibility and antimicrobial properties [7,16].
In the packaging sector, thermoplastic starch (TPS) reinforced with sisal fibers has been developed to replace single-use plastics, increasing mechanical strength and reducing the typical fragility of TPS [17]. In the construction industry, PHA or PLA composites with bamboo fibers have been studied for lightweight panels and structural materials, taking advantage of the rapid growth and availability of this fiber [18]. These examples demonstrate that the appropriate selection of the biopolymer matrix and fiber type, combined with surface treatments and interfacial optimization, are crucial for the final performance of the biocomposite and its industrial viability, aiming for scalability [19].

3. Extraction Sources and Processing Requirements

Classic fiber extraction methods such as mechanical decortication, dew/water retting, enzymatic retting, alkaline treatments, and chemical degumming processes are used to remove non-cellulosic fractions such as pectin, hemicelluloses, and lignin. These parameters control the elastic modulus, mechanical strength, and thermal stability when the fibers are used as reinforcement in biopolymers such as PLA, PHAs, and TPS [21,22,23].
The choice of extraction method determines key parameters such as yield, degree of polymerization (DP) of cellulose, and energy demand of the process. Biological and enzymatic processes tend to present high yields and better preservation of the cellulose structure, since they act more selectively in the removal of pectin and hemicelluloses, minimizing the degradation of cellulosic chains [21,24,25] (Figure 2). In contrast, alkaline chemical treatments, although effective in the surface cleaning of fibers and in increasing roughness, which ultimately favors fiber–matrix adhesion in composites, can reduce the DP of cellulose due to chemical attack on polymer chains and require higher energy consumption and environmental control of the generated effluents [25,26,27].
The retting method is particularly crucial for bast fibers such as hemp, flax, jute, ramie, and kenaf, because the severity and duration of the process alter the degree of fiber separation, bundle diameter, and the presence of impurities, directly impacting the uniformity and reproducibility of composites. Chemical processes using NaOH or peroxides produce cleaner fibers and ensure greater surface roughness, improving adhesion to hydrophobic matrices. However, these treatments can reduce the molar mass of cellulose and generate environmental residues if the effluents produced during the process are not properly treated [21,22,28]. Experimental comparative studies with water hyacinth fibers (Eichhornia crassipes) show that combined methods (mechanical–chemical) produce cleaner fibers with better surface quality, whereas exclusively mechanical methods present lower energy consumption but greater variability of properties and possible mechanical damage to the fibers [29]. Therefore, the choice of method will determine the fiber quality, its mechanical and thermal properties, and environmental and operational impacts [21,22,28].
Extraction routes with lower environmental impact and better-quality control are being studied (Table 1). Enzymatic and biological retting is one of the methods that uses microorganisms or enzymes such as pectinases and cellulases, which allow fiber separation with lower energy consumption and without the intensive use of harsh chemicals [21,24]. In studies such as that of [30], it is possible to observe that the yield of enzymatic extraction is higher than that of dew retting, with values of 24% and 16%, respectively, which may vary depending on the enzyme used, while the energy demand in the case of enzymatic retting becomes lower, since dew retting requires a longer processing time [30].
Physico-thermochemical processes, such as steam explosion, promote the fragmentation of the lignocellulosic matrix and facilitate subsequent refining and fibrillation steps; however, they are associated with high energy demand and potential reduction in DP due to the high temperatures and pressures involved [31]. The study by [32] demonstrates that when applying steam explosion pretreatment to rice straw for cellulose extraction, an efficiency of around 70% and a yield of approximately 20% were obtained under optimized conditions (~200 °C, 33 min). Although the study does not report the energy demand, it is possible to predict that there is high energy demand associated with the use of high temperatures and pressure, an intrinsic characteristic of steam explosion processes [32].
In turn, the use of solvents considered green, such as ionic liquids (ILs) and deep eutectic solvents (DESs), has shown high yields in the selective fractionation of lignin and hemicelluloses and potential for the production of high-purity microcellulose and nanocellulose, as can be observed in the study by [33] in which methods based on deep eutectic solvents (DESs) proved to be effective in the removal of hemicellulose with a total mass yield of more than 90%, higher than that of alkaline extraction (57%). The degree of polymerization can be observed indirectly, since structural analysis by X-ray diffraction revealed that DES treatment resulted in lower crystallinity than alkaline methods, which implies that its degree of polymerization is also lower than that obtained by alkaline methods [33]. In terms of energy consumption, although DES is classified as a green route, its lower efficiency in cellulose recovery implies higher energy demand, whereas the alkaline route presents moderate energy consumption, but with higher fractionation efficiency [23,24,34,35].
Thus, jointly considering yield, preservation of the degree of polymerization, and energy demand, enzymatic and biological methods present the best overall compromise for obtaining high-quality fibers with lower energy impact, whereas chemical and physico-thermochemical routes offer higher cleaning and fractionation efficiency, but with higher energy costs and greater risk of structural degradation of cellulose [21,22,25,35,36]. Table 2 presents some examples of extraction methods to obtain fibers from natural sources.

4. Characterization Methods

Characterization methods are crucial for understanding the intrinsic properties of plant-derived biopolymers and natural fibers, which allows for the prediction of their performance in composite applications [38]. This understanding is important for improving material selection, adjusting processing parameters, and supporting the structural integrity and lifespan of sustainable composite materials. Comprehensive characterization helps in developing high-performance biocomposites by revealing how modifications in fiber extraction, chemical treatment, and matrix integration affect the final product’s characteristics [39,40]. These analytical techniques provide insights into the hierarchical structure, chemical composition, and mechanical responses of these materials, guiding their tailored application.

4.1. Structural and Morphological Analysis

Scanning electron microscopy is a primary tool for visualizing the surface morphology of individual fibers and the fracture surfaces of composites, offering insights into fiber–matrix adhesion and dispersion [41]. This technique allows for the identification of surface defects, fiber pull-out, and matrix cracking, which are crucial indicators of composite failure mechanisms. Beyond visual inspection, advanced techniques such as transmission electron microscopy and atomic force microscopy can further elucidate the ultrastructure and nanomechanical properties of individual fibers and their interfaces within the biopolymer matrix, providing critical information on fiber orientation and stress distribution at the nanoscale [42]. The elucidated fiber morphology within the biopolymer matrix can be directly correlated with the improved mechanical performance of the composites.
Both scanning electron microscopy (SEM) and atomic force microscopy (AFM) play complementary roles in characterizing surface morphology of fibers and surfaces in composite materials. SEM offers a high-resolution imaging of surface topography and texture at the microscale, revealing details like fiber roughness, voids, and matrix–fiber interfaces on fracture surfaces; e.g., SEM micrographs of PLA-PBS blends reinforced with fibers show uniform matrix distribution and microstructural uniformity, aiding evaluation of mechanical integrity in sustainable structural materials [43]. However, SEM offers primarily 2D projections and requires conductive coating for non-conductive samples like natural fibers, potentially introducing artifacts [43,44]. AFM complements SEM by delivering true 3D topographic maps and quantitative nanomechanical data at higher resolution (nanoscale), ideal for precise height measurements, roughness quantification, and elasticity mapping on fiber surfaces without vacuum or coating needs [43]. AFM quantifies surface changes post-treatment, such as increased roughness from polymer accumulation on hair-like fibers, which translates to natural fiber studies in composites [44]. Its limitations include smaller scan areas, slower imaging, and sensitivity to tip artifacts, making it less suited for large-scale fracture overviews compared to SEM’s broader field of view. Together, these techniques provide comprehensive morphology insights, with SEM for overview and chemical context and AFM for nanoscale precision in green composite research [43,45].
Moreover, as AFM uses mechanical probe scanning, it enables true 3D topography on diverse samples but is limited by smaller scan areas and slower speeds, while SEM suits microscale overviews [43].
Several studies have reported that the incorporation of natural fibers, such as kenaf, jute, or ramie, into biopolymer matrices like polylactic acid (PLA) and polybutylene succinate (PBS) leads to significant enhancements in mechanical properties. For instance, alkalized PLA–kenaf fiber composites exhibit approximately a 30% increase in tensile strength compared to neat PLA, while PBS–hemp fiber composites with surface-modified fibers demonstrate superior flexural strength as a result of improved fiber–matrix interfacial adhesion [10,45]. Figure 3 presents a schematic representation of microscopy techniques used for visualizing the surface morphology of fibers.
X-ray diffraction is fundamental for determining the crystallinity index of biopolymers, such as cellulose, a parameter that directly influences the fiber’s stiffness and strength [46,47]. Fourier transform infrared and Raman spectroscopies provide crucial information about the functional groups present, detecting structural changes after chemical or physical fiber modification treatments [48]. Hence, the enhanced interfacial adhesion promotes more effective load transfer from the matrix to the reinforcing fibers, thereby improving tensile and flexural properties. Furthermore, stronger and more homogeneous interfaces modify damage evolution by reducing premature fiber pull-out and enabling crack deflection and controlled debonding mechanisms. These processes increase energy dissipation during fracture, resulting in improved overall toughness of the composite [49].

4.2. Thermal Characterization

The thermal stability of fibers and composites is evaluated by thermogravimetric analysis, which provides information on mass loss as a function of temperature and identifies degradation steps associated with hemicellulose, cellulose, and lignin behavior [50]. The thermal behavior of fibers and their composites is strongly influenced by the intrinsic properties of the fibers, such as cellulose, hemicellulose, and lignin content, as well as by their interactions with the polymer matrix. Therefore, a comprehensive understanding of these factors is essential to study composites behavior under varying temperature conditions. Differential scanning calorimetry is used to determine thermal transitions, such as melting, glass transition, and crystallization temperatures, which are important for predicting composite behavior during processing. Dynamic mechanical analysis complements this information by characterizing viscoelastic properties, like storage and the loss modulus, and reveals the material’s response to cyclic stress [51].

4.3. Mechanical Characterization

The efficacy of plant fibers as reinforcements is rigorously assessed through mechanical characterization. Essential mechanical properties, including strength, the elastic modulus, and toughness, are determined via tensile, flexural, and impact tests that adhere to ASTM (American Society for Testing and Materials) and ISO (International Organization for Standardization) standards. Furthermore, nanoindentation offers a sophisticated technique for quantifying the local hardness and elastic modulus of individual fibers or specific composite regions at a microscopic level, enabling a more profound understanding of the relationship between surface modifications and overall material performance [52,53].
These detailed mechanical characterizations are indispensable for understanding the load-bearing capacity and deformation behavior of plant-based composites under various service conditions, ensuring their suitability for diverse engineering applications [54]. The mean microfibrillar angle of cellulosic fibers, often determined by X-ray diffraction, significantly influences their mechanical behavior and tensile properties, thereby affecting the final composite’s performance [55]. The evaluation of these mechanical properties is particularly critical when assessing the impact of various fiber treatments—physical, chemical, or biological—designed to optimize fiber–matrix adhesion and stress transfer within the composite [5].

4.4. Surface and Chemical Composition Analysis

Fiber–matrix adhesion, a critical factor in composite performance, is directly influenced by the surface composition. Therefore, characterization techniques are selected based on their ability to provide complementary information on elemental composition, functional groups, and surface energetics. Techniques such as X-ray photoelectron spectroscopy are employed to quantify the elemental proportions on the fiber surface, providing essential data on surface chemistry. Furthermore, surface energy and wettability, which serve as indicators of fiber–matrix compatibility, are evaluated through contact angle measurements. Complementary chemical analyses, including the determination of lignin, cellulose, and hemicellulose content, offer crucial insights into the fiber’s inherent composition and potential interactions within the matrix [41,56]. These insights are paramount for understanding how various surface treatments, such as alkalization or salinization, modify the fiber’s surface energy and enhance interfacial bonding with the biopolymer matrix, thereby improving stress transfer efficiency and overall composite mechanical performance [41]. Hence, the combined use of XPS, contact angle measurements, and compositional analyses provides a robust framework for evaluating fiber–matrix interactions and optimizing surface treatments for improved composite performance.

4.5. Biodegradability and Environmental Performance

Natural fibers, predominantly composed of cellulose, hemicellulose, and lignin, are inherently biodegradable, making them environmentally advantageous over synthetic fibers. Their biodegradation occurs through natural enzymatic and microbial activity, which breaks down fiber components into simpler substances that can be reintegrated into ecosystems, minimizing long-term environmental impact [5]. This biodegradability ensures that fiber-reinforced biopolymer composites contribute less to persistent waste and microplastic pollution compared to conventional petrochemical-based composites [57,58]. However, the rate and extent of degradation depend on factors such as fiber type, chemical treatments, matrix composition, and environmental conditions, including moisture, temperature, and microbial presence. For example, cellulose-based fibers like cotton can decompose substantially within weeks to months under suitable conditions, even when treated with dyes or finishes, thereby reducing landfill burden and ecological toxicity [59].
Moreover, natural fiber composites typically exhibit lower carbon footprints and require less energy during production than synthetic counterparts, reinforcing their role in sustainable material solutions. Nonetheless, the heterogeneous nature of fiber composites poses challenges for recycling, as fiber degradation may adversely affect mechanical properties upon reprocessing. Future works are relevant to improving both biodegradability and recyclability, matching performance with environmental sustainability. Thus, the use of natural fibers in biopolymer composites embodies a shift toward eco-friendly materials that align with circular economic principles and global efforts to reduce pollution and resource consumption [60].
To accurately forecast the environmental impact and behavior of composites reinforced with plant fibers, biodegradation tests are performed under soil, water, or composting conditions [5]. Additionally, accelerated aging studies are conducted to simulate real-world operational scenarios, allowing for a thorough evaluation of their durability and the rate at which their properties degrade over time. These critical assessments collectively emphasize the necessity of ensuring the long-term sustainability and ecological safety of the bio-based composite materials that are developed [61,62]. The characterization methods collectively ensure that biopolymers and natural fibers are thoroughly understood, enabling their optimal design and application in sustainable composite systems [5].
Biodegradability and environmental characterization techniques provide both short-term performance data and long-term sustainability indicators. The combined application of biodegradation testing, accelerated aging, and environmental impact assessment enables a comprehensive evaluation of the ecological viability of biocomposites, supporting their potential application in sustainable products [63,64,65].

5. Reinforcement of Fiber-Based Composites and Products

5.1. Reinforcement Mechanisms

The use of plant fibers as reinforcing agents in polymer matrices represents a sustainable alternative to replace synthetic fibers in various applications. Reinforcement occurs through load transfer between a matrix and fiber, with interfacial adhesion, aspect ratio, and fiber distribution being determining factors for composite performance. The inherent properties of plant fibers, such as their high specific strength and modulus, combined with their renewable nature, contribute significantly to their appeal as reinforcement materials [52]. This section shows fundamental mechanisms through which these natural fibers enhance the mechanical properties of biopolymer composites, alongside the critical parameters influencing their reinforcing efficiency [41].
Fibers act as structural elements that support and distribute stress, thereby reducing matrix deformation. This stress distribution prevents catastrophic failure by allowing the composite to sustain higher loads than either component could individually [66,67]. The higher the aspect ratio is, the greater the reinforcement capacity is, provided that interfacial adhesion is efficient. Fiber orientation also significantly influences composite properties: fibers aligned with the load axis demonstrably increase strength, while randomly distributed fibers impart isotropy [67]. Effective stress transfer from the weaker matrix to the stronger fibers is predicated on strong interfacial bonding, often achieved through chemical or physical treatments that enhance wettability and adhesion [68].
For instance, studies have shown that the incorporation of flax fibers into polylactic acid can enhance tensile strength by approximately 50% and increase stiffness to between 3.4 and 8.4 GPa with 30 wt.% fiber loading [54]. Similarly, coir fiber reinforcement in polypropylene can optimize mechanical properties and reduce water absorption through chemical treatment, attributed to improved fiber–matrix bonding [54]. The mechanical properties of bamboo fiber-reinforced high-density polyethylene composites have also shown improvement with increased fiber loading, highlighting the potential for natural fibers to enhance polymer performance [1]. This enhancement is crucial given the increasing demand for sustainable materials in various industrial sectors, including the automotive industry, construction, and packaging, where specific strength and stiffness are critical [54,69].

5.2. Fiber Modification and Treatments

Natural fibers offer high mechanical strength and serve as strong alternatives to conventional fibers in many fields. These materials are known to contain inherent constituents such as lignin, hemicellulose, and waxes, which tend to result in suboptimal adhesion with hydrophobic matrices. To circumvent this limitation, various chemical, physical, and biological treatment methodologies are employed [52,70]. The high crystallinity degree and the presence of strong intermolecular hydrogen bonding in cellulose makes solubilization in common solvents difficult [71,72]. Several strategies have been employed to enhance the fiber–matrix interfacial compatibility in biocomposites, particularly to overcome challenges associated with chemical functionalization [63] and biological treatment [73] of lignocellulosic fibers.
Chemical functionalization is a primary strategy to mitigate these challenges. Alkali treatment (mercerization) is effective in removing superficial impurities, non-cellulosic materials, and waxes, thereby reducing hydrophilicity and increasing surface roughness for better mechanical interlocking [63]. Beyond alkalization, acetylation involves the replacement of hydroxyl groups by acetyl groups on the fiber surface, which reduces moisture absorption and improves hydrophobicity [5]. Similarly, silane coupling agents form covalent bonds with hydroxyl groups on the fiber surface, significantly improving resistance to moisture and refining the mechanical properties of the composite [74].
In addition to traditional chemical methods, green techniques have emerged. Subcritical water hydrolysis (SBW) and supercritical water hydrolysis (SCW) modify surface characteristics by altering the hydrophilic–hydrophobic balance through cellulose depolymerization. SBW hydrolysis enhances solvent accessibility and efficiently dissolves undesirable amorphous regions to increase the overall yield [71], taking place primarily at crystalline surfaces to preserve fiber properties [72]. SBW hydrolysis enhances the maximum solvent accessibility into the cellulose fibers and efficient dissolution of undesirable amorphous regions to increase the overall yield [71]. Further, this technique only takes place at their crystalline surfaces with low reaction rates preserving the properties of the fiber [72]. SCW hydrolysis, occurring under high-temperature and high-pressure conditions, promotes the cleavage of glycosidic bonds and facilitates partial lignin removal, increasing cellulose purity and surface cleanliness [75,76]. Moreover, the technique facilitates the partial removal of lignin, thereby increasing cellulose purity and surface cleanliness, which are essential for improving fiber–matrix adhesion in polymer composites [75,76].
Biological treatments offer another eco-friendly avenue. Enzymatic treatment based on hydrolysis allows for the conversion of lignocellulosic biomass with higher selectivity and lower energy costs than harsh chemical processes. The mechanism of enzymatic hydrolysis and the relationship between the substrate structure and function of various glycosyl hydrolase [65]. Both aerobic and anaerobic bacteria, as well as fungi from Ascomycetes and Basidiomycetes species, possess specific glycosyl hydrolases capable of degrading pectin and hemicellulose without damaging the cellulose core [65,77].
Finally, physical methods such as atmospheric pressure plasma treatment improve interfacial adhesion without affecting the bulk characteristics of cellulose [78]. The introduction of reactive species and polar groups (e.g., –OH, –COOH, –NH2) increases surface energy and compatibility with polar matrices [79]. However, plasma treatment presents challenges related to uniformity, particularly when dealing with fine fibers or materials with high surface-to-volume ratios, which can result in limited homogeneity [80].

5.3. Biopolymer Matrices for Fiber Reinforcement

Plant fibers can be incorporated into both natural polymers, such as starch, proteins, lignin, and pectin, and biodegradable synthetic biopolymers like polylactic acid, polyhydroxyalkanoates, and polybutylene succinate. Compatibility between fiber and a matrix is crucial for load transfer and to prevent premature failure [1]. Research addresses this by developing effective coupling agents and optimizing processing conditions to bridge the differences between typically hydrophilic natural fibers and often hydrophobic biopolymer matrices [5]. These agents facilitate stronger interfacial adhesion, essential for high-performance biocomposites that leverage the reinforcing capabilities of plant fibers [81,82]. Despite extensive research, challenges persist in achieving optimal compatibility between plant fibers and biopolymer matrices due to their inherent compositional differences [15,83].
Biopolymers are intensively studied as matrix materials, owing to their potential for waste management reduction. For example, biopolymer matrices derived from renewable sources such as starch and chitosan offer properties suitable for packaging and medical devices [84]. The development of nanocellulose fiber-reinforced starch biopolymer composites has shown increased mechanical strength, flexibility, and thermal stability. These nanocomposite films show great potential as eco-friendly, biodegradable packaging materials [9]. Furthermore, the morphology of chitosan/cellulose composites offers better stress transfer and compatibility, playing a crucial role in determining enhanced mechanical and thermal performance [85]. The incorporation of chitosan, starch, and PLA into these cellulose-rich formulations presents a promising strategy for developing sustainable materials for diverse applications [64].
The reinforcement of plant fibers with biopolymers also faces challenges regarding the recycling complex process, limited fire resistance, concerns about long-term sustainability, and issues with scalability and cost-effectiveness. To mitigate these, it is essential to develop more efficient recycling methods to reduce environmental impact, to formulate legislations about recycling steps of fiber-derived composites, to standardize the recycling process across the world, since products and packaging can be globally distributed, to innovate formulations and treatments that enhance fire resistance, to improve the durability and sustainability of fiber-reinforced polymers production processes, and to optimize manufacturing techniques to make high-performance applications more scalable and economically viable [8,74].

5.4. Applications and Products

Biocomposites reinforced with plant fibers are increasingly being adopted across diverse sectors due to their favorable mechanical properties and environmental benefits [39]. The automotive industry, for example, extensively utilizes these composites for interior components, offering excellent insulation and a lighter weight compared to traditional materials [10]. Furthermore, their biodegradability and lower carbon footprint align with the growing environmental consciousness of manufacturers and consumers, positioning them as viable alternatives to synthetic fiber composites [1].
In construction, they are employed in non-structural elements like insulation panels and partition walls, benefiting from their acoustic and thermal properties, along with their renewable nature. Beyond automotive and construction, the packaging sector is increasingly adopting biopolymer composites for their improved barrier properties and reduced environmental impact [54].
This widespread adoption underscores the versatility and increasing maturity of plant-based fiber reinforcement technologies, expanding their utility into diverse applications such as sporting goods and consumer electronics where lightweight, high-performance, and sustainable materials are highly valued [1,83].
The development of novel hybrid composites, combining different plant fibers such as jute and acacia, further expands the potential for tailored properties and enhanced performance in these applications [86]. Consequently, the versatility of plant-based composites extends to furniture and other structural components, offering an eco-friendly and cost-effective alternative to conventional materials [87].

5.5. Challenges and Future Perspectives

Despite ongoing advancements, significant hurdles persist in achieving fiber standardization due to inherent natural variations. Furthermore, the large-scale applicability of current treatment methodologies and their compatibility with various polymer matrices remain critical limitations. Addressing these challenges requires intensive research into robust and scalable fiber modification techniques that can ensure consistent fiber properties and optimal interfacial adhesion across a spectrum of biopolymer systems, thereby enhancing their commercial viability and expanding their application range [5].
Nevertheless, the growing trend of valorizing agro-industrial waste streams as a fiber source, coupled with integration into circular economy frameworks, presents a promising pathway for enhancing the market competitiveness of these sustainable materials against conventional alternatives. This approach not only reduces waste but also provides a cost-effective and environmentally friendly solution for composite material production [83].
Moreover, chemical functionalization can be a strategy to mitigate the challenges in reinforcing plant fibers in plant-derived composites [74]. Some of these approaches can include: (I) alkali treatment, which removes the superficial impurities, non-cellulosic materials and waxes, reducing hydrophilicity and improving the composite adhesion; (II) acetylation, by the replacement of hydroxyl groups by acetyl groups on fiber surface, which reduces moisture, improves hydrophobicity and the composite strength; (III) use of silane coupling agents, which forms covalent bonds with hydroxyl groups on fiber surface, improving resistance to moisture and consequently refining the mechanical properties of the composite [74].
Waste biomass systematic utilization significantly mitigates environmental impact while simultaneously reducing the reliance on virgin resources and lowering overall production costs [83]. Such strategies are essential for accelerating the transition towards a truly sustainable materials economy, offering a compelling alternative to traditional, petroleum-based composites [83].
In this context, some gaps and future directions can be pointed to translate laboratory advances into widespread industrial adoption, such as:
(a)
Fiber–Matrix Interfacial Optimization: Despite advances in chemical treatments such as alkali mercerization and compatibilizers, achieving consistently strong and durable adhesion between hydrophilic natural fibers and hydrophobic biopolymer matrices remains a challenge. Future research should focus on novel surface modification techniques and coupling agents that can enhance interface compatibility without compromising biodegradability [88].
(b)
Standardization of Processing Techniques: The extrusion, molding, and hybrid composite fabrication processes vary widely in parameters and equipment, generating variability in the final properties of fiber-reinforced biopolymer composites. There is a need for standardized protocols and scalable manufacturing processes that ensure reproducibility and optimize mechanical and thermal performance [89].
(c)
Comprehensive Life Cycle and Sustainability Assessments: While natural fibers and biopolymers are widely promoted for their environmental benefits, holistic assessments encompassing lifecycle carbon footprints, end-of-life biodegradability, and resource use are insufficient. Future studies should integrate such analyses to quantify real-world sustainability impacts and identify improvement opportunities [90].
(d)
Expansion of Application Domains: Current research largely focuses on the construction, automotive, and packaging sectors. Emerging fields such as biomedical devices, flexible electronics, and high-performance structural components require tailored composite formulations and performance evaluations. Exploring multifunctional composites incorporating natural fibers and biopolymers could open new avenues for innovation [91].

6. Conclusions

This review presented the role of plant fibers and biopolymers in the development of sustainable composite materials, demonstrating that the combination of these constituents can balance mechanical performance and environmental responsibility. Natural fibers offer advantages such as renewability, biodegradability, and low density, while biopolymer matrices contribute to reducing environmental impact throughout the materials’ application. The analysis showed that composite performance is strongly influenced not only by the intrinsic properties of the fibers and the characteristics of the matrix, but also, decisively, by the fiber extraction and treatment routes, which control parameters such as yield, degree of polymerization of cellulose, surface cleanliness, and process energy demand. Biological and enzymatic methods stand out when greater preservation of the cellulose structure and lower energy impact are desired, being more suitable for applications that require better mechanical integrity and process sustainability. In contrast, chemical and physico-thermochemical routes show higher efficiency in biomass cleaning and fractionation, being preferable when interfacial adhesion and surface homogeneity of the fibers are priorities, although they entail higher energy consumption and a greater risk of structural degradation. Although significant advances have been achieved through chemical surface treatments and improved manufacturing techniques, challenges remain, particularly related to interfacial compatibility, moisture sensitivity, processing reproducibility, and the lack of standardized testing protocols. In this context, the present article sought to understand these parameters so that future research on biopolymer composites reinforced with natural fibers should prioritize rational selection strategies of the extraction method according to the final application, as well as scalable and environmentally benign interfacial treatments, combined with standardized comparative studies under controlled conditions to optimize mechanical performance, durability, and environmental impact. Overall, these materials represent a promising pathway for the development of high-performance and environmentally friendly composites, aligned with the principles of the circular economy and the reduction in dependence on fossil resources.

Author Contributions

Conceptualization, O.V.d.S. and B.E.T.-C.; methodology, K.S.L.M., Y.L.-P., N.N.d.S.M., W.H.F., O.V.d.S. and B.E.T.-C.; software, K.S.L.M., Y.L.-P., N.N.d.S.M., W.H.F., O.V.d.S. and B.E.T.-C.; formal analysis, K.S.L.M., Y.L.-P., N.N.d.S.M., W.H.F., O.V.d.S. and B.E.T.-C.; investigation, K.S.L.M., Y.L.-P., N.N.d.S.M., W.H.F., O.V.d.S. and B.E.T.-C.; resources, O.V.d.S. and B.E.T.-C.; data curation, W.H.F., O.V.d.S. and B.E.T.-C.; writing—original draft preparation, K.S.L.M., Y.L.-P., N.N.d.S.M., W.H.F., O.V.d.S. and B.E.T.-C.; writing—review and editing, W.H.F., O.V.d.S. and B.E.T.-C.; visualization, W.H.F., O.V.d.S. and B.E.T.-C.; supervision, O.V.d.S. and B.E.T.-C.; project administration, B.E.T.-C.; funding acquisition, B.E.T.-C. All authors have read and agreed to the published version of the manuscript.

Funding

This study was partially financed (with scholarships) by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior—Brasil (CAPES)—Finance Code 001 and by FAPERJ—Carlos Chagas Filho Foundation for Research Support of the State of Rio de Janeiro (SEI-RJ Process: E-26/204.549/2024; SEI-RJ Process: E-26/210.932/2024; SEI-RJ Process: E-26/210.613/2025).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

No new data were created or analyzed in this study. Data sharing is not applicable.

Conflicts of Interest

The authors declare no conflicts of interest.

Abbreviations

The following abbreviations are used in this manuscript:
ASTMAmerican Society for Testing and Materials
DESsDeep eutectic solvents
ILsIonic liquids
ISOInternational Organization for Standardization
PHAPolyhydroxyalkanoates
PLAPolylactic acid
SBWSubcritical water hydrolysis
SCWSupercritical water hydrolysis
TPSThermoplastic starch

References

  1. Prakash, S.O.; Sahu, P.; Madhan, M.; Santhosh, A.J. A Review on Natural Fibre-Reinforced Biopolymer Composites: Properties and Applications. Int. J. Polym. Sci. 2022, 2022, 7820731. [Google Scholar] [CrossRef] [Scilit]
  2. Keya, K.N.; Kona, N.A.; Koly, F.A.; Maraz, K.M.; Islam, M.N.; Khan, R.A. Natural fiber reinforced polymer composites: History, types, advantages, and applications. Mater. Eng. Res. 2019, 1, 69–87. [Google Scholar] [CrossRef] [Scilit]
  3. Sahu, P.; Gupta, M.K. A review on the properties of natural fibres and its bio-composites: Effect of alkali treatment. Proc. Inst. Mech. Eng. Part L J. Mater. Des. Appl. 2020, 234, 198–217. [Google Scholar] [CrossRef] [Scilit]
  4. Zamora-Mendoza, L.; Gushque, F.; Yanez, S.; Jara, N.; Álvarez-Barreto, J.F.; Zamora-Ledezma, C.; Dahoumane, S.A.; Alexis, F. Plant Fibers as Composite Reinforcements for Biomedical Applications. Bioengineering 2023, 10, 804. [Google Scholar] [CrossRef] [Scilit] [PubMed]
  5. Maiti, S.; Islam, M.R.; Uddin, M.A.; Afroj, S.; Eichhorn, S.J.; Karim, N. Sustainable Fiber-Reinforced Composites: A Review. Adv. Sustain. Syst. 2022, 6, 2200258. [Google Scholar] [CrossRef] [Scilit]
  6. Beg, M.D.H.; Pickering, K.L.; Akindoyo, J.O.; Gauss, C. Recyclable hemp hurd fibre-reinforced PLA composites for 3D printing. J. Mater. Res. Technol. 2024, 33, 4439–4447. [Google Scholar] [CrossRef] [Scilit]
  7. Samir, A.; Ashour, F.H.; Hakim, A.A.A.; Bassyouni, M. Recent advances in biodegradable polymers for sustainable applications. NPJ Mater. Degrad. 2022, 6, 68. [Google Scholar] [CrossRef] [Scilit]
  8. Edah, G.O.; Atiba, J.O.; Fayomi, O.S.I. Advancements in fibre-reinforced polymers: Properties, applications (A mini review). Next Mater. 2025, 8, 100743. [Google Scholar] [CrossRef] [Scilit]
  9. Firdaus, A.H.M.; Sapuan, S.M.; Siddiqui, V.U.; Atiqah, A.; Zainudin, E.S. Mechanical, physical and morphological properties of arrowroot starch reinforced arrowroot nanocrystalline cellulose biopolymer nanocomposites film. Biomass Bioenergy 2025, 202, 108230. [Google Scholar] [CrossRef] [Scilit]
  10. Elfaleh, I.; Abbassi, F.; Habibi, M.; Ahmad, F.; Guedri, M.; Nasri, M.; Garnier, C. A comprehensive review of natural fibers and their composites: An eco-friendly alternative to conventional materials. Results Eng. 2023, 19, 101271. [Google Scholar] [CrossRef] [Scilit]
  11. Flórez, M.; Cazón, P.; Vázquez, M. Selected Biopolymers’ Processing and Their Applications: A Review. Polymers 2023, 15, 641. [Google Scholar] [CrossRef] [Scilit]
  12. Das, A.; Ringu, T.; Ghosh, S.; Pramanik, N. A comprehensive review on recent advances in preparation, physicochemical characterization, and bioengineering applications of biopolymers. Polym. Bull. 2023, 80, 7247–7312. [Google Scholar] [CrossRef] [Scilit]
  13. Muir, V.G.; Burdick, J.A. Chemically Modified Biopolymers for the Formation of Biomedical Hydrogels. Chem. Rev. 2021, 121, 10908–10949. [Google Scholar] [CrossRef] [Scilit] [PubMed]
  14. Çağdaş, B.; Tunalı, D.; Türk, M. Natural Biopolymers and Their Applications in Bioengineering. In Nano-Biomaterials in Tissue Repair and Regeneration; Springer: Berlin/Heidelberg, Germany, 2024; pp. 19–54. [Google Scholar] [CrossRef] [Scilit]
  15. Lee, C.H.; Khalina, A.; Lee, S.H. Importance of interfacial adhesion condition on characterization of plant-fiber-reinforced polymer composites: A review. Polymers 2021, 13, 438. [Google Scholar] [CrossRef] [Scilit] [PubMed]
  16. Madhushree, M.; Vairavel, P.; Mahesha, G.T.; Bhat, K.S. A Comprehensive Review of Cellulose and Cellulose-Based Materials: Extraction, Modification, and Sustainable Applications. J. Nat. Fibers 2024, 21, 2418357. [Google Scholar] [CrossRef] [Scilit]
  17. Song, Y.; Nie, K.; Liu, H.; Jiang, W.; Zhang, Y.; Bai, R.; Yang, F.; Ragauskas, A.; Ma, J. Separation Process of Plant Fibers for Textile and Composite Application: A Review of Recent Advances. J. Nat. Fibers 2024, 21, 2406460. [Google Scholar] [CrossRef] [Scilit]
  18. Kamarudin, S.H.; Basri, M.S.M.; Rayung, M.; Abu, F.; Ahmad, S.; Norizan, M.N.; Osman, S.; Sarifuddin, N.; Desa, M.S.Z.M.; Abdullah, U.H.; et al. A Review on Natural Fiber Reinforced Polymer Composites (NFRPC) for Sustainable Industrial Applications. Polymers 2022, 14, 3698. [Google Scholar] [CrossRef] [Scilit]
  19. Shelly, D.; Singhal, V.; Jaidka, S.; Banea, M.D.; Lee, S.Y.; Park, S.J. Mechanical performance of bio-based fiber reinforced polymer composites: A review. Polym. Compos. 2025, 46, S9–S43. [Google Scholar] [CrossRef] [Scilit]
  20. Yıldırım, R.; Karakaya, N.; Liebau, B.; Welten, T.; Bayram, B.; Kodal, M.; Özkoç, G. From Plant to Polymers: Micro-Processing Sisal Fiber-Reinforced PLA/PHA Bio-LFTs at Laboratory Scale. Polymers 2025, 17, 1618. [Google Scholar] [CrossRef] [Scilit]
  21. Angulu, M.; Gusovius, H.J. Retting of Bast Fiber Crops Like Hemp and Flax—A Review for Classification of Procedures. Fibers 2024, 12, 28. [Google Scholar] [CrossRef] [Scilit]
  22. Zimniewska, M. Hemp Fibre Properties and Processing Target Textile: A Review. Materials 2022, 15, 1901. [Google Scholar] [CrossRef] [Scilit]
  23. Eleutério, T.; Trota, M.J.; Meirelles, M.G.; Vasconcelos, H.C. A Review of Natural Fibers: Classification, Composition, Extraction, Treatments, and Applications. Fibers 2025, 13, 119. [Google Scholar] [CrossRef] [Scilit]
  24. Magalhães, S.; Fernandes, C.; Pedrosa, J.F.S.; Alves, L.; Medronho, B.; Ferreira, P.J.T.; Rasteiro, M.d.G. Eco-Friendly Methods for Extraction and Modification of Cellulose: An Overview. Polymers 2023, 15, 3138. [Google Scholar] [CrossRef] [Scilit]
  25. Farag, G.Y.; Taleb, E.M.A.A.; Hamouda, T. Natural Fibers Extraction Methods and Properties: A Review. Egypt. J. Chem. 2024, 68, 445–464. [Google Scholar] [CrossRef] [Scilit]
  26. Bekele, A.E.; Lemu, H.G.; Jiru, M.G. Study of the Effects of Alkali Treatment and Fiber Orientation on Mechanical Properties of Enset/Sisal Polymer Hybrid Composite. J. Compos. Sci. 2023, 7, 37. [Google Scholar] [CrossRef] [Scilit]
  27. Sathish, S.; Karthi, N.; Prabhu, L.; Gokulkumar, S.; Balaji, D.; Vigneshkumar, N.; Farhan, T.A.; AkilKumar, A.; Dinesh, V. A review of natural fiber composites: Extraction methods, chemical treatments and applications. Mater. Today Proc. 2021, 45, 8017–8023. [Google Scholar] [CrossRef] [Scilit]
  28. Majid, M.S.A.; Ridzuan, M.J.M.; Lim, K.H. Effect of nanoclay filler on mechanical and morphological properties of napier/epoxy composites. In Interfaces in Particle and Fibre Reinforced Composites: Current Perspectives on Polymer, Ceramic, Metal and Extracellular Matrices; Elsevier: Amsterdam, The Netherlands, 2019; pp. 137–162. [Google Scholar] [CrossRef] [Scilit]
  29. Chonsakorn, S.; Srivorradatpaisan, S.; Mongkholrattanasit, R. Effects of different extraction methods on some properties of water hyacinth fiber. J. Nat. Fibers 2019, 16, 1015–1025. [Google Scholar] [CrossRef] [Scilit]
  30. De Prez, J.; Willem, A.; Vuure, V.; Ivens, J.; Aerts, G.; Van De Voorde, I. Enzymatic treatment of flax for use in composites. Biotechnol. Rep. 2018, 20, e00294. [Google Scholar] [CrossRef] [Scilit] [PubMed]
  31. Ma, C.; Ni, L.; Guo, Z.; Zeng, H.; Wu, M.; Zhang, M.; Zheng, B. Principle and Application of Steam Explosion Technology in Modification of Food Fiber. Foods 2022, 11, 3370. [Google Scholar] [CrossRef] [Scilit]
  32. Serrano-Martínez, V.M.; Pérez-Aguilar, H.; Carbonell-Blasco, M.P.; Arán-Ais, F.; Orgilés-Calpena, E. Steam Explosion-Based Method for the Extraction of Cellulose and Lignin from Rice Straw Waste. Appl. Sci. 2024, 14, 2059. [Google Scholar] [CrossRef] [Scilit]
  33. Casanova, F.; Freixo, R.; Pereira, C.F.; Ribeiro, A.B.; Costa, E.M.; Pintado, M.E.; Ramos, Ó.L. Comparative Study of Green and Traditional Routes for Cellulose Extraction from a Sugarcane By-Product. Polymers 2023, 15, 1251. [Google Scholar] [CrossRef] [Scilit]
  34. Baraka, F.; Erdocia, X.; Velazco-Cabral, I.; Hernández-Ramos, F.; Dávila-Rodríguez, I.; Maugin, M.; Labidi, J. Impact of deep eutectic solvent pre-treatment on the extraction of cellulose nanofibers. Cellulose 2024, 31, 9645–9660. [Google Scholar] [CrossRef] [Scilit]
  35. Barbará, P.V.; Choudhary, H.; Nakasu, P.S.; Al-Ghatta, A.; Han, Y.; Hopson, C.; Aravena, R.I.; Mishra, D.K.; Ovejero-Pérez, A.; Simmons, B.A.; et al. Recent Advances in the Use of Ionic Liquids and Deep Eutectic Solvents for Lignocellulosic Biorefineries and Biobased Chemical and Material Production. Chem. Rev. 2025, 125, 5461–5583. [Google Scholar] [CrossRef] [Scilit]
  36. Fu, Y.; Gu, H.; Wu, H.F.; Shi, S.Q. Comparative Life Cycle Assessment of Bacterial and Thermochemical Retting of Hemp. Materials 2024, 17, 4164. [Google Scholar] [CrossRef] [Scilit]
  37. Isogai, A. Wood nanocelluloses: Fundamentals and applications as new bio-based nanomaterials. J. Wood Sci. 2013, 59, 449–459. [Google Scholar] [CrossRef] [Scilit]
  38. Nagaraja, S.; Anand, P.B.; Ammarullah, M.I. Synergistic advances in natural fibre composites: A comprehensive review of the eco-friendly bio-composite development, its characterization and diverse applications. RSC Adv. 2024, 14, 17594–17611. [Google Scholar] [CrossRef] [Scilit]
  39. Liu, W.; Chen, T.; Fei, M.-E.; Qiu, R.; Yu, D.; Fu, T.; Qiu, J. Properties of natural fiber-reinforced biobased thermoset biocomposites: Effects of fiber type and resin composition. Compos. B Eng. 2019, 171, 87–95. [Google Scholar] [CrossRef] [Scilit]
  40. Kumar, N.; Rawat, P.; Kandasami, R.K. Enhancing the characteristics of natural coir fiber yarns using biopolymer for textile reinforced cementitious composites. Constr. Build. Mater. 2025, 470, 140427. [Google Scholar] [CrossRef] [Scilit]
  41. Islam, M.Z.; Sarker, E.; Rahman, M.; Islam, R.; Ahmed, A.T.M.F.; Mahmud, S. Green composites from natural fibers and biopolymers: A review on processing, properties, and applications. J. Reinf. Plast. Compos. 2022, 41, 526–557. [Google Scholar] [CrossRef] [Scilit]
  42. Ananthapadmanaban, D. Summary of Some Selected Characterization Methods of Geopolymers. In Geopolymers and Other Geosynthetics; IntechOpen: Hamilton, NJ, USA, 2020. [Google Scholar] [CrossRef] [Scilit]
  43. Swain, P.P.; Penedo, M.; Fantner, G.E. A Comprehensive Analysis of Combined AFM/SEM Systems for In-Situ Nanoscale Characterizations and Multiparametric Correlative Microscopy. Microsc. Microanal. 2025, 31, ozaf110. [Google Scholar] [CrossRef] [Scilit]
  44. Monteiro, V.F.; Natal, A.M.D.; Soledade, L.E.B.; Longo, E. Morphological analysis of polymers on hair fibers by SEM and AFM. Mater. Res. 2003, 6, 501–506. [Google Scholar] [CrossRef] [Scilit]
  45. Sari, N.H.; Suteja; Fatriasari, W. Integration of Biopolyesters and Natural Fibers in Structural Composites: An Innovative Approach for Sustainable Materials. J. Renew. Mater. 2025, 13, 1521–1546. [Google Scholar] [CrossRef] [Scilit]
  46. Jiyas, N.; Sasidharan, I.; Kumar, K.B.; Gopakumar, B.; Dan, M.; Sabulal, B. Mechanical superiority of Pseudoxytenanthera bamboo for sustainable engineering solutions. Sci. Rep. 2023, 13, 18169. [Google Scholar] [CrossRef] [Scilit]
  47. French, A.D. How Crystalline is My Cellulose Specimen? Probing the Limits of X-ray Diffraction. Bioresources 2022, 17, 5557–5561. [Google Scholar] [CrossRef] [Scilit]
  48. Lengowski, E.C.; Magalhães, W.L.E.; Nisgoski, S.; de Muniz, G.I.B.; Satyanarayana, K.G.; Lazzarotto, M. New and improved method of investigation using thermal tools for characterization of cellulose from eucalypts pulp. Thermochim. Acta 2016, 638, 44–51. [Google Scholar] [CrossRef] [Scilit]
  49. Chen, Y.; Prasad, V.; Yasar, M.; Murphy, N.; Ivankovic, A. Enhancing interfacial performance and fracture toughness of carbon fibre reinforced thermoplastic composites. Compos. Part A Appl. Sci. Manuf. 2024, 187, 108434. [Google Scholar] [CrossRef] [Scilit]
  50. Neto, J.S.S.; de Queiroz, H.F.M.; Aguiar, R.A.A.; Banea, M.D. A Review on the Thermal Characterisation of Natural and Hybrid Fiber Composites. Polymers 2021, 13, 4425. [Google Scholar] [CrossRef] [Scilit]
  51. Khanam, P.N.; Al-Maadeed, M.A.; Khanam, P.N. Silk as a reinforcement in polymer matrix composites. In Advances in Silk Science and Technology; Elsevier: Amsterdam, The Netherlands, 2015; pp. 143–170. [Google Scholar] [CrossRef] [Scilit]
  52. McKay, I.; Vargas, J.; Yang, L.; Felfel, R.M. A Review of Natural Fibres and Biopolymer Composites: Progress, Limitations, and Enhancement Strategies. Materials 2024, 17, 4878. [Google Scholar] [CrossRef] [Scilit]
  53. Zhao, Y.R.; Wang, L.; Dong, Y.Y. Micromechanical Properties of Steel-Fiber-Reinforced Cementitious Composites Characterized with Nanoindentation. Adv. Civ. Eng. 2021, 2021, 6673283. [Google Scholar] [CrossRef] [Scilit]
  54. Prasad, V.; Vijayakumar, A.A.; Jose, T.; George, S.C. A Comprehensive Review of Sustainability in Natural-Fiber-Reinforced Polymers. Sustainability 2024, 16, 1223. [Google Scholar] [CrossRef] [Scilit]
  55. Rekha, B.; NagarajaGanesh, B. X-ray Diffraction: An Efficient Method to Determine Microfibrillar Angle of Dry and Matured Cellulosic Fibers. J. Nat. Fibers 2022, 19, 3689–3696. [Google Scholar] [CrossRef] [Scilit]
  56. Sajith, S. Investigation on effect of chemical composition of bio-fillers on filler/matrix interaction and properties of particle reinforced composites using FTIR. Compos. B Eng. 2019, 166, 21–30. [Google Scholar] [CrossRef] [Scilit]
  57. Pickering, K.L.; Efendy, M.G.A.; Le, T.M. A review of recent developments in natural fibre composites and their mechanical performance. Compos. Part A Appl. Sci. Manuf. 2016, 83, 98–112. [Google Scholar] [CrossRef] [Scilit]
  58. Munimathan, A.; Muthu, K.; Subramani, S.; Rajendran, S. Environmental behaviour of synthetic and natural fibre reinforced composites: A review. Adv. Mech. Eng. 2024, 16, 1–19. [Google Scholar] [CrossRef] [Scilit]
  59. Nofal, R.M. Biodegradable Textiles, Recycling, Sustainability Achievement. In Handbook of Biodegradable Materials; Springer: Berlin/Heidelberg, Germany, 2022; pp. 1–37. [Google Scholar] [CrossRef] [Scilit]
  60. Kamran, F.; Afshar, H.; Shahi, F. Recent Advances and Applications of Sustainable and Recyclable Polymers. Polym. Eng. Sci. 2025, 65, 3845–3879. [Google Scholar] [CrossRef] [Scilit]
  61. Gallos, A.; Paës, G.; Allais, F.; Beaugrand, J. Lignocellulosic fibers: A critical review of the extrusion process for enhancement of the properties of natural fiber composites. RSC Adv. 2017, 7, 34638–34654. [Google Scholar] [CrossRef] [Scilit]
  62. Niutta, C.B.; Ciardiello, R.; Tridello, A.; Paolino, D.S. Epoxy and Bio-Based Epoxy Carbon Fiber Twill Composites: Comparison of the Quasi-Static Properties. Materials 2023, 16, 1601. [Google Scholar] [CrossRef] [Scilit]
  63. Verma, D.; Goh, K.L. Effect of Mercerization/Alkali Surface Treatment of Natural Fibres and Their Utilization in Polymer Composites: Mechanical and Morphological Studies. J. Compos. Sci. 2021, 5, 175. [Google Scholar] [CrossRef] [Scilit]
  64. Wittmar, A.S.M.; Prymak, O.; Homm, T.; Surholt, F.; Uhlemann, J.; Stranghöner, N.; Ulbricht, M. Formation of all-biopolymer-based composites with cellulose as the main component. RSC Appl. Interfaces 2025, 2, 508–520. [Google Scholar] [CrossRef] [Scilit]
  65. Yang, B.; Dai, Z.; Ding, S.Y.; Wyman, C.E. Enzymatic hydrolysis of cellulosic biomass. Biofuels 2011, 2, 421–449. [Google Scholar] [CrossRef] [Scilit]
  66. Sharma, H.; Kumar, A.; Rana, S.; Sahoo, N.G.; Jamil, M.; Kumar, R.; Sharma, S.; Li, C.; Kumar, A.; Eldin, S.M.; et al. Critical review on advancements on the fiber-reinforced composites: Role of fiber/matrix modification on the performance of the fibrous composites. J. Mater. Res. Technol. 2023, 26, 2975–3002. [Google Scholar] [CrossRef] [Scilit]
  67. Fernández, A.; Santangelo-Muro, M.; Fernández-Blázquez, J.P.; Lopes, C.S.; Molina-Aldareguia, J.M. Processing and properties of long recycled-carbon-fibre reinforced polypropylene. Compos. B Eng. 2021, 211, 108653. [Google Scholar] [CrossRef] [Scilit]
  68. Amin, M.N.; Ahmad, W.; Khan, K.; Ahmad, A. A Comprehensive Review of Types, Properties, Treatment Methods and Application of Plant Fibers in Construction and Building Materials. Materials 2022, 15, 4362. [Google Scholar] [CrossRef] [Scilit]
  69. Seculi, F.; Espinach, F.X.; Julián, F.; Delgado-Aguilar, M.; Mutjé, P.; Tarrés, Q. Evaluation of the Interface Strength in the Abaca-Fiber-Reinforced Bio-Polyethylene Composites. Polymers 2023, 15, 2686. [Google Scholar] [CrossRef] [Scilit] [PubMed]
  70. Mundhe, A.; Kandasubramanian, B. Advancements in natural fiber composites: Innovative chemical surface treatments, characterizaton techniques, environmental sustainability, and wide-ranging applications. Hybrid Adv. 2024, 7, 100282. [Google Scholar] [CrossRef] [Scilit]
  71. Osei-Bonsu, R.; Hoque, M.; McMichael, P.S.; Foster, E.J. Subcritical water digestion of woody biomass: Extraction of cellulose nanomaterials under acid-lean condition. Nanoscale Adv. 2024, 6, 3923–3933. [Google Scholar] [CrossRef] [Scilit] [PubMed]
  72. Liu, Y.; Fu, H.; Zhang, W.; Liu, H. Effect of Crystalline Structure on the Catalytic Hydrolysis of Cellulose in Subcritical Water. ACS Sustain. Chem. Eng. 2022, 10, 5859–5866. [Google Scholar] [CrossRef] [Scilit]
  73. Aravindh, M.; Sathish, S.; Prabhu, L.; Raj, R.R.; Bharani, M.; Patil, P.P.; Karthick, A.; Luque, R. Effect of Various Factors on Plant Fibre-Reinforced Composites with Nanofillers and Its Industrial Applications: A Critical Review. J. Nanomater. 2022, 2022, 4455106. [Google Scholar] [CrossRef] [Scilit]
  74. Shaker, K.; Fauster, E. An overview of challenges in processing of sustainable plant fiber composites. Ind. Crops Prod. 2025, 233, 121397. [Google Scholar] [CrossRef] [Scilit]
  75. Leontijevic, V.; Fechter, T.; Cantero, D.; Jaeger, P.; Cocero, M.J. Surface wettability of lignin materials from supercritical water hydrolysis of wood. J. Supercrit. Fluids 2025, 217, 106458. [Google Scholar] [CrossRef] [Scilit]
  76. Sikhosana, T.S.; Malebo, N.J.; Mofokeng, T.G.; Motloung, M.P.; Mochane, M.J. Sawdust as a Byproduct of Wood Processing: Properties, Applications and a Reinforcing Filler in Hybrid Polymer Composites. Polymers 2025, 17, 1523. [Google Scholar] [CrossRef] [Scilit] [PubMed]
  77. Hsin, K.T.; Lee, H.; Huang, Y.-C.; Lin, G.-J.; Lin, P.-Y.; Lin, Y.-C.J.; Chen, P.-Y. Lignocellulose degradation in bacteria and fungi: Cellulosomes and industrial relevance. Front. Microbiol. 2025, 16, 1583746. [Google Scholar] [CrossRef] [Scilit] [PubMed]
  78. Gupta, U.S.; Dhamarikar, M.; Dharkar, A.; Chaturvedi, S.; Kumrawat, A.; Giri, N.; Tiwari, S.; Namdeo, R. Plasma modification of natural fiber: A review. Mater. Today Proc. 2021, 43, 451–457. [Google Scholar] [CrossRef] [Scilit]
  79. Hair, A.H.A.; Salleh, K.M.; Mazlan, N.S.N.; Khairunnisa-Atiqah, M.K.; Purhanudin, N.; Akhiri, A.S.M.; Zakaria, S.; Awang, R. Optimisation of nitrogen plasma exposure time for surface modification of cotton fibre. Bioresources 2024, 19, 5699–5716. [Google Scholar] [CrossRef] [Scilit]
  80. Primc, G.; Mozetič, M. Plasma Treatment of Nanocellulose to Improve the Surface Properties. Polymers 2024, 16, 2516. [Google Scholar] [CrossRef] [Scilit]
  81. Sánchez-Safont, E.L.; Aldureid, A.; Lagarón, J.M.; Cabedo, L.; Gámez-Pérez, J. Study of the Compatibilization Effect of Different Reactive Agents in PHB/Natural Fiber-Based Composites. Polymers 2020, 12, 1967. [Google Scholar] [CrossRef] [Scilit]
  82. Arbelaiz, A.; Txueka, U.; Mezo, I.; Orue, A. Biocomposites Based on Poly(Lactic Acid) Matrix and Reinforced with Lignocellulosic Fibers: The Effect of Fiber Type and Matrix Modification. J. Nat. Fibers 2022, 19, 1–14. [Google Scholar] [CrossRef] [Scilit]
  83. Yashas, Y.G.; Nagaraju, S.B.; Puttegowda, M.; Verma, A.; Rangappa, S.M.; Siengchin, S. Biopolymer-Based Composites: An Eco-Friendly Alternative from Agricultural Waste Biomass. J. Compos. Sci. 2023, 7, 242. [Google Scholar] [CrossRef] [Scilit]
  84. Castro-Dominguez, B.; Gröls, J.R.; Alkandari, S.; Perge, L.; Sierra-Avila, C.; Ramirez, H.Z.; Fontes, M.d.L.; Yamada, C.; Lazarini, S.C.; Silva, J.M.; et al. Biopolymers and biocomposites: A comprehensive review of feedstocks, functionalities, and advanced manufacturing techniques for sustainable applications. Biotechnol. Sustain. Mater. 2025, 2, 8. [Google Scholar] [CrossRef] [Scilit]
  85. Daoudi, H.; Benhamou, A.A.; Moubarik, A.; El Achaby, M.; Kassab, Z. Influence of morphological diversity of cellulose nanocrystals and nanospheres on nanocomposites with chitosan. Cellulose 2024, 32, 941–964. [Google Scholar] [CrossRef] [Scilit]
  86. Kurien, R.A.; Bodaghi, M.; Mathew, N.D.; Paul, M.; Ravi, S.V.; Praveen, P. Fabrication, Properties, and Morphologies of Novel Acacia–Jute Hybrid Polymer Composites. J. Compos. Sci. 2025, 9, 316. [Google Scholar] [CrossRef] [Scilit]
  87. Martijanti, M.; Sutarno, S.; Juwono, A.L. Polymer Composite Fabrication Reinforced with Bamboo Fiber for Particle Board Product Raw Material Application. Polymers 2021, 13, 4377. [Google Scholar] [CrossRef] [Scilit] [PubMed]
  88. Saha, S.; Das, S.; Rahman, M.Z. Hybridization in natural fiber composites: Enhanced performance and sustainability. Compos. B Eng. 2026, 308, 112986. [Google Scholar] [CrossRef] [Scilit]
  89. Kirschnick, U.; Feuchter, M.; Ravindran, B.; Salzmann, M.; Duretek, I.; Fauster, E.; Schledjewski, R. Manufacturing bio-based fiber-reinforced polymer composites: Process performance in RTM and VARI processes. Adv. Manuf. Polym. Compos. Sci. 2024, 10, 2379205. [Google Scholar] [CrossRef] [Scilit]
  90. Hottle, T.A.; Bilec, M.M.; Landis, A.E. Biopolymer production and end of life comparisons using life cycle assessment. Resour. Conserv. Recycl. 2017, 122, 295–306. [Google Scholar] [CrossRef] [Scilit]
  91. Yuan, L.L.; Wang, H.M.; Wu, Y.C.; Hou, Q.X.; Sun, R.C. The booming lignin-derived functional composites/nanocomposites. Compos. B Eng. 2024, 287, 111869. [Google Scholar] [CrossRef] [Scilit]
Coatings 16 00289 g001
Figure 1. The main morphological structure of a fiber filament.
Figure 1. The main morphological structure of a fiber filament.
Coatings 16 00289 g001
Coatings 16 00289 g002
Figure 2. Comparison between the main fiber extraction methods.
Figure 2. Comparison between the main fiber extraction methods.
Coatings 16 00289 g002
Coatings 16 00289 g003
Figure 3. Schematic representation of the microscopy techniques used for visualizing the surface morphology of fibers.
Figure 3. Schematic representation of the microscopy techniques used for visualizing the surface morphology of fibers.
Coatings 16 00289 g003
Table 1. Key properties, limitations, and typical trade-offs of some common biopolymer matrices.
Table 1. Key properties, limitations, and typical trade-offs of some common biopolymer matrices.
BiopolymersKey PropertiesLimitationsTypical Trade-OffsReferences
PLAHigh stiffness; excellent processability comparable to polystyrene.Inherent brittleness;
low thermal stability.		High rigidity and processability vs. low toughness.[6,7]
PHAsSuperior biodegradability; biocompatibility suitable for medical uses.High production costs; narrow processing window.Excellent biodegradability vs. high cost and narrow processing.[11]
TPSDerived from abundant, low-cost sources.High hydrophilicity (poor water resistance, mechanical variation); often requires blending or chemical modification.Low-cost vs. poor water resistance and mechanical consistency.[15]
Table 2. Examples of extraction methods to obtain fiber from natural resources.
Table 2. Examples of extraction methods to obtain fiber from natural resources.
Extraction MethodFeaturesFiberYieldPolymerization DegreeEnergy
Demand		Reference
Retting (dew/water/
controlled)		Separates fibers by degradation of binding substances; can improve strength if well controlled; quality varies with time and environment; degradation may occur.Hemp, linen, juteMedium to highHigh when well controlled; may decrease due to excessive microbial degradation.Low[21,30]
Enzymatic retting/
degumming		More selective; reduces pectin without attacking cellulose; reduces time and variability; less environmental impact than chemical treatments; improves sample homogeneity.Hemp, flax, ramieHighHigh (preservation of cellulose)Low to moderate[30,36]
Alkaline treatments/mercerizationRemoves hemicellulose, lignin, and waxes; increases roughness and crystallinity; improves adhesion; concentration and time can degrade fibers and generate effluents.Sisal, jute, cotton, bambooMediumMedium to low (reduction in GP by alkaline cleavage)Moderate[26,37]
Physical pretreatment + steam explosionEffective for opening lignocellulosic matrix, reducing hemicellulose and partial lignin, generating dispersible fibrils; without the use of organic solvents.Bamboo, sisal, strawMediumMedium (possible reduction by thermal/mechanical shear)High[29,32]
Green solvents (ILs/DES)Selective extraction produces nanocellulose with consistent quality and presents a favorable environmental profile when the solvent is recovered and recycled.Cotton, bamboo, sisalHighVariable (maybe high under mild conditions)High[35]
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Miki, K.S.L.; Lima-Pereira, Y.; Muniz, N.N.d.S.; Ferreira, W.H.; dos Santos, O.V.; Teixeira-Costa, B.E. From Plants to Performance: A Sustainable Approach to Fiber Reinforcement Using Biopolymers. Coatings 2026, 16, 289. https://doi.org/10.3390/coatings16030289

AMA Style

Miki KSL, Lima-Pereira Y, Muniz NNdS, Ferreira WH, dos Santos OV, Teixeira-Costa BE. From Plants to Performance: A Sustainable Approach to Fiber Reinforcement Using Biopolymers. Coatings. 2026; 16(3):289. https://doi.org/10.3390/coatings16030289

Chicago/Turabian Style

Miki, Karine Sayuri Lima, Ytaiara Lima-Pereira, Nelícia Nunes de Souza Muniz, Willian Hermogenes Ferreira, Orquidea Vasconcelos dos Santos, and Barbara Elisabeth Teixeira-Costa. 2026. "From Plants to Performance: A Sustainable Approach to Fiber Reinforcement Using Biopolymers" Coatings 16, no. 3: 289. https://doi.org/10.3390/coatings16030289

APA Style

Miki, K. S. L., Lima-Pereira, Y., Muniz, N. N. d. S., Ferreira, W. H., dos Santos, O. V., & Teixeira-Costa, B. E. (2026). From Plants to Performance: A Sustainable Approach to Fiber Reinforcement Using Biopolymers. Coatings, 16(3), 289. https://doi.org/10.3390/coatings16030289

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop