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Keywords = polyamide waste

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17 pages, 3356 KiB  
Article
Impact of Adaptive Process Control on Mechanical Properties of Plastic Parts and Process Robustness
by Tomasz Olszewski, Danuta Matykiewicz and Michał Jakubowicz
Appl. Sci. 2025, 15(16), 8829; https://doi.org/10.3390/app15168829 - 10 Aug 2025
Viewed by 286
Abstract
This work aimed to assess the influence of the iQ Weight Control System on the weight, dimensional stability, and mechanical properties of injection-molded samples. The properties of products made from glass fiber-reinforced polyamide and 50% regrind from post-production waste were evaluated. The mechanical [...] Read more.
This work aimed to assess the influence of the iQ Weight Control System on the weight, dimensional stability, and mechanical properties of injection-molded samples. The properties of products made from glass fiber-reinforced polyamide and 50% regrind from post-production waste were evaluated. The mechanical properties, such as impact strength and tensile strength, were measured to determine the material’s performance. Additionally, a spiral flow test was conducted to verify the process robustness and repeatability when producing with either virgin material or a blend of virgin and regrind material. The spiral flow test, which involves injecting the polymer melt into a spiral mold, provides insights into the processability and flow characteristics of the polymer under high shear rates. This test is crucial for assessing the consistency of the injection molding process and ensuring that the material maintains its properties across different production batches. Results demonstrated that, despite the viscosity reduction associated with regrind, the system successfully maintained a consistent shot weight, thereby stabilizing the amount of material injected into the mold cavity. The iQ Weight Control System activation led to an increase in impact strength from 9.50 kJ/m2 to 10.78 kJ/m2 for virgin samples and from 9.26 kJ/m2 to 9.73 kJ/m for a 50/50 virgin/regrind blend. Full article
(This article belongs to the Special Issue Mechanical Properties and Numerical Modeling of Advanced Materials)
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22 pages, 5403 KiB  
Article
Degradation of Synthetic and Natural Textile Materials Using Streptomyces Strains: Model Compost and Genome Exploration for Potential Plastic-Degrading Enzymes
by Vukašin Janković, Brana Pantelic, Marijana Ponjavic, Darka Marković, Maja Radetić, Jasmina Nikodinovic-Runic and Tatjana Ilic-Tomic
Microorganisms 2025, 13(8), 1800; https://doi.org/10.3390/microorganisms13081800 - 1 Aug 2025
Viewed by 407
Abstract
Given the environmental significance of the textile industry, especially the accumulation of nondegradable materials, there is extensive development of greener approaches to fabric waste management. Here, we investigated the biodegradation potential of three Streptomyces strains in model compost on polyamide (PA) and polyamide-elastane [...] Read more.
Given the environmental significance of the textile industry, especially the accumulation of nondegradable materials, there is extensive development of greener approaches to fabric waste management. Here, we investigated the biodegradation potential of three Streptomyces strains in model compost on polyamide (PA) and polyamide-elastane (PA-EA) as synthetic, and on cotton (CO) as natural textile materials. Weight change of the materials was followed, while Fourier-Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) were used to analyze surface changes of the materials upon biodegradation. The bioluminescence-based toxicity test employing Aliivibrio fischeri confirmed the ecological safety of the tested textiles. After 12 months, the increase of 10 and 16% weight loss, of PA-EA and PA, respectively, was observed in compost augmented with Streptomyces sp. BPS43. Additionally, a 14% increase in cotton degradation was recorded after 2 months in compost augmented with Streptomyces sp. NP10. Genome exploration of the strains was carried out for potential plastic-degrading enzymes. It highlighted BPS43 as the most versatile strain with specific amidases that show sequence identity to UMG-SP-1, UMG-SP-2, and UMG-SP-3 (polyurethane degrading enzymes identified from compost metagenome). Our results showcase the behavior of Streptomyces sp. BPS43 in the degradation of PA and PA-EA textiles in composting conditions, with enzymatic potential that could be further characterized and optimized for increased synthetic textile degradation. Full article
(This article belongs to the Section Environmental Microbiology)
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22 pages, 6500 KiB  
Article
The Effect of Bio-Based Polyamide 10.10 and Treated Fly Ash on Glass-Fiber-Reinforced Polyamide 6 Properties
by George-Mihail Teodorescu, Zina Vuluga, Toma Fistoș, Sofia Slămnoiu-Teodorescu, Jenica Paceagiu, Cristian-Andi Nicolae, Augusta Raluca Gabor, Marius Ghiurea, Cătălina Gîfu and Rodica Mariana Ion
Polymers 2025, 17(14), 1950; https://doi.org/10.3390/polym17141950 - 16 Jul 2025
Viewed by 336
Abstract
Increased concern for human health and the environment has pushed various industries to adopt new approaches towards satisfying modern regulations. Strategies to achieve these approaches include utilizing lightweight materials, repurposing waste materials, and substituting synthetic polymers with bio-based counterparts. This study investigates the [...] Read more.
Increased concern for human health and the environment has pushed various industries to adopt new approaches towards satisfying modern regulations. Strategies to achieve these approaches include utilizing lightweight materials, repurposing waste materials, and substituting synthetic polymers with bio-based counterparts. This study investigates the effects of treated fly ash (C) and bio-based polyamide 10.10 (PA10) on the thermal, morphological, and mechanical properties of glass fiber (GF)-reinforced polyamide 6 (PA6). Our main objective was to develop a composite that would allow for the partial replacement of glass fiber in reinforced polyamide 6 composites (PA6-30G) while maintaining a favorable balance of mechanical properties. Composites processed via melt processing demonstrated enhanced mechanical properties compared to PA6-30G. Notably, significant improvements were observed in impact strength and tensile strain at break. The addition of PA10 resulted in increases of 18% in impact strength and 35% in tensile strain relative to PA6-30G. Complementary, structural and morphological analyses confirmed strong interfacial interactions within the composite matrix. These findings indicate that a PA6/PA10 hybrid composite may represent a viable alternative material for potential automotive applications. Full article
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46 pages, 1588 KiB  
Review
Advancements in Organic Solvent Nanofiltration: The Critical Role of Polyamide Membranes in Sustainable Industrial Applications
by Shivshankar Chaudhari, Sunilesh Chakravarty, YoungHo Cho, JinWon Seo, MinYoung Shon and SeungEun Nam
Processes 2025, 13(7), 2212; https://doi.org/10.3390/pr13072212 - 10 Jul 2025
Viewed by 837
Abstract
Organic solvent nanofiltration (OSN) has emerged as a transformative platform for molecular separation, offering energy-efficient and high-performance alternatives to conventional separation techniques across the food, petrochemical, and pharmaceutical industries. At the core of this advancement lie polyamide membranes, whose exceptional chemical resilience, tunable [...] Read more.
Organic solvent nanofiltration (OSN) has emerged as a transformative platform for molecular separation, offering energy-efficient and high-performance alternatives to conventional separation techniques across the food, petrochemical, and pharmaceutical industries. At the core of this advancement lie polyamide membranes, whose exceptional chemical resilience, tunable architecture, and compatibility with a wide range of organic solvents have positioned them as the material of choice for industrial OSN applications. Recent progress encompassing nanostructured additives, controlled interfacial polymerization, and advanced crosslinking strategies has led to significant improvements in membrane selectivity, permeability, and operational stability. As OSN continues to gain traction in sustainable chemical processing, enabling reductions in both energy consumption and environmental waste, ongoing challenges such as membrane fouling, structural degradation, and limited solvent resistance remain critical barriers to broader adoption. This review critically examines the role of polyamide membranes in OSN, emphasizing their structural versatility, physicochemical attributes, and capacity to meet the growing demands of sustainable separation technologies. Full article
(This article belongs to the Section Materials Processes)
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23 pages, 7753 KiB  
Article
Microplastic Pollution on the Beaches of the Black Sea in Romania and Bulgaria
by Mirel Glevitzky, Gabriela-Alina Dumitrel, Gerlinde Iuliana Rusu, Daniela Toneva, Stoyan Vergiev, Mihai-Teopent Corcheş, Ana-Maria Pană and Maria Popa
Appl. Sci. 2025, 15(9), 4751; https://doi.org/10.3390/app15094751 - 25 Apr 2025
Cited by 2 | Viewed by 1558
Abstract
Microplastic pollution has gained attention in recent years due to its adverse impact on the environment. As a major threat to marine ecosystems and biota, the accumulation of microplastics along coastlines has become a growing concern. This study focused on quantifying and characterizing [...] Read more.
Microplastic pollution has gained attention in recent years due to its adverse impact on the environment. As a major threat to marine ecosystems and biota, the accumulation of microplastics along coastlines has become a growing concern. This study focused on quantifying and characterizing the presence, distribution, and composition of microplastics along the beaches of Romania and Bulgaria. Microplastics were extracted from beach sand samples using a saturated NaCl solution. The particles were then analyzed through FT-IR and DSC spectral analyses to identify their chemical composition. Sampling was conducted across several resorts along the Romanian and Bulgarian coastlines. The findings revealed varying concentrations of microplastics across different beaches, with Romanian beaches showing concentrations of between 40 and 213 particles per sample (470–2500 microplastics/kg), which were notably higher in areas like Mamaia and Costinești. On Bulgarian beaches, the average concentrations reached up to 137 particles per sample (1612 microplastics/kg), particularly in areas like Sunny Beach and Nessebar. Polyethylene (PE) was identified as the most prevalent polymer (55%), followed by polyamide (PA), polypropylene (PP), polyethylene terephthalate (PET), and polyurethane (PU). These polymers were linked to common sources such as packaging, textiles, and industrial products. Microscopic examination, combined with FT-IR and DSC spectral analysis, confirmed the plastic nature of the particles, revealing distinct chemical structures characteristic of each material type. This study underscores the widespread contamination of Romanian and Bulgarian beaches with microplastics, emphasizing the environmental risks to coastal ecosystems. The presence of synthetic polymers highlights the urgent need for policies targeting plastic waste management to mitigate the growing pollution in marine environments. Full article
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26 pages, 4983 KiB  
Article
Mechanical, Thermal, and Flammability Properties of Eco-Friendly Nanocomposites from Recycled PET/PA-11 Blends Reinforced with Graphene Nanoplatelets
by Unsia Habib, Mohammed E. Ali Mohsin, Zahid Iqbal Khan, Zurina Mohamad, Norhayani Othman, Suleiman Mousa, SK Safdar Hossain and Syed Sadiq Ali
Polymers 2025, 17(8), 1038; https://doi.org/10.3390/polym17081038 - 11 Apr 2025
Cited by 2 | Viewed by 932
Abstract
This study investigates the development of sustainable nanocomposites using recycled polyethylene terephthalate (RPET) and polyamide 11 (PA-11) blends reinforced with graphene nanoplatelets (GNPs). RPET/PA-11 blends were compatibilized with 2 phr Joncryl® and processed using melt blending followed by injection moulding. The effects [...] Read more.
This study investigates the development of sustainable nanocomposites using recycled polyethylene terephthalate (RPET) and polyamide 11 (PA-11) blends reinforced with graphene nanoplatelets (GNPs). RPET/PA-11 blends were compatibilized with 2 phr Joncryl® and processed using melt blending followed by injection moulding. The effects of varying GNP contents (1–4 phr) on mechanical, thermal, and flame-retardant properties were analysed. The nanocomposite with 1 phr GNPs exhibited an optimal balance of mechanical, flame-retardant, and thermal properties, along with improved dispersion compared to higher GNP loadings. Higher GNP concentrations led to increased stiffness but also promoted agglomeration, which negatively impacted tensile and impact strength. Thermal analysis revealed that GNPs influenced the cold crystallization behaviour of RPET, while the TGA results indicated a moderate enhancement in thermal stability. The maximum degradation temperature (Tmax) increased from 410.38 °C to 430.06 °C with 1 phr GNPs but declined at higher loadings. Similarly, flammability tests showed an improvement in the limiting oxygen index (LOI) from 19 to 24. Morphological analysis confirmed that GNPs facilitated PA-11 dispersion within the RPET matrix, particularly at lower GNP concentrations (1 phr). These findings highlight the potential of RPET/PA-11/GNP nanocomposites for multifunctional applications, providing an optimal balance between mechanical performance, thermal stability, and flame resistance. This research highlights the synergistic effect of GNPs in achieving sustainable, high-performance materials, addressing the challenges of plastic waste management and the need for eco-friendly engineering solutions for industries such as automotive, packaging, and construction. Full article
(This article belongs to the Collection Feature Papers in Polymer Processing and Engineering)
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18 pages, 5294 KiB  
Article
Multi-Layer Oil- and Water-Resistant Food Containers Made Using Cellulose Nanofibril-Laminated Wood Veneer
by Nabanita Das, Islam Hafez, Douglas Bousfield and Mehdi Tajvidi
Polysaccharides 2025, 6(2), 28; https://doi.org/10.3390/polysaccharides6020028 - 2 Apr 2025
Viewed by 1006
Abstract
This work aimed at replacing per- or poly-fluoroalkyl substance (PFAS)-based food-serving containers with wood-based, oil- and grease-resistant food-serving containers. A novel container was developed by laminating wet cellulose nanofibril (CNF) films to both sides of yellow birch wood veneer using a food-grade polyamide–epichlorohydrin [...] Read more.
This work aimed at replacing per- or poly-fluoroalkyl substance (PFAS)-based food-serving containers with wood-based, oil- and grease-resistant food-serving containers. A novel container was developed by laminating wet cellulose nanofibril (CNF) films to both sides of yellow birch wood veneer using a food-grade polyamide–epichlorohydrin additive (PAE) as an adhesive. CNFs significantly improved the wood veneer container’s mechanical strength and barrier properties. The container’s mechanical testing results showed significant increases in flexural strength and modulus of elasticity (MOE) values in both parallel and perpendicular directions to the grain. All formulations of the container showed excellent oil and grease resistance properties by passing “kit” number 12 based on the TAPPI T 559 cm-12 standard. The water absorption tendency of the formulation treated at higher temperature, pressure, and longer press time showed similar performance to commercial paper plates containing PFASs. The developed composite demonstrates superior flexural strength and barrier properties, presenting a sustainable alternative to PFASs in food-serving containers. Both wood and CNFs stand out for their remarkable eco-friendliness, as they are biodegradable and naturally compostable. This unique characteristic not only helps minimize waste but also promotes a healthier environment. If scaled up, these novel containers may present a solution to the oil/grease resistance of bio-based food containers. Full article
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20 pages, 2598 KiB  
Article
Recycling Fiber-Reinforced Polyamide Waste from the Automotive Industry: Life Cycle Assessment (LCA) of an Advanced Pyrolysis Process to Reclaim Glass Fibers and Valuable Chemicals
by Blanca María Caballero, Alexander Lopez-Urionabarrenechea, Jean Paul Gonzalez-Arcos, Borja Benjamín Perez-Martinez, Esther Acha, Maider Iturrondobeitia, Julen Ibarretxe, Aritz Esnaola and Maider Baskaran
Materials 2025, 18(7), 1594; https://doi.org/10.3390/ma18071594 - 1 Apr 2025
Viewed by 791
Abstract
The generation of pyrolysis liquids and gases with poor quality is a limiting factor for the development of the recycling process of fiber-reinforced plastic waste. In this article, the life cycle assessment (LCA) of an advanced two-step pyrolysis process to recycle glass fiber-reinforced [...] Read more.
The generation of pyrolysis liquids and gases with poor quality is a limiting factor for the development of the recycling process of fiber-reinforced plastic waste. In this article, the life cycle assessment (LCA) of an advanced two-step pyrolysis process to recycle glass fiber-reinforced polyamide waste is presented. First, the solid waste is pyrolyzed by heating up at 3 °C/min to 500 °C in a tank reactor. The generated volatiles are subsequently thermally cracked at 900 °C in a tubular packed bed reactor. The process is able to reclaim the glass fibers similarly to the conventional one reactor pyrolysis, while producing liquids and gases with better properties. The large quantity of oxygenated pyrolysis oils generated in the conventional pyrolysis are cracked into gaseous hydrocarbons, CO, CO2 and a minor aqueous liquid. The pyrolysis gases become the main product of the process, presenting an interesting composition of hydrogen (39.9 vol.%), methane (22.5 vol.%), carbon monoxide (19.5 vol.%) and ethylene (10.8 vol.%). The LCA shows that advanced pyrolysis demonstrates better environmental performance than conventional pyrolysis, avoiding fossil resource scarcity and reducing global warming by half and human carcinogenic toxicity by one third. Full article
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46 pages, 7489 KiB  
Review
Environmental Impact of Textile Materials: Challenges in Fiber–Dye Chemistry and Implication of Microbial Biodegradation
by Arvind Negi
Polymers 2025, 17(7), 871; https://doi.org/10.3390/polym17070871 - 24 Mar 2025
Cited by 4 | Viewed by 3725
Abstract
Synthetic and natural fibers are widely used in the textile industry. Natural fibers include cellulose-based materials like cotton, and regenerated fibers like viscose as well as protein-based fibers such as silk and wool. Synthetic fibers, on the other hand, include PET and polyamides [...] Read more.
Synthetic and natural fibers are widely used in the textile industry. Natural fibers include cellulose-based materials like cotton, and regenerated fibers like viscose as well as protein-based fibers such as silk and wool. Synthetic fibers, on the other hand, include PET and polyamides (like nylon). Due to significant differences in their chemistry, distinct dyeing processes are required, each generating specific waste. For example, cellulose fibers exhibit chemical inertness toward dyes, necessitating chemical auxiliaries that contribute to wastewater contamination, whereas synthetic fibers are a major source of non-biodegradable microplastic emissions. Addressing the environmental impact of fiber processing requires a deep molecular-level understanding to enable informed decision-making. This manuscript emphasizes potential solutions, particularly through the biodegradation of textile materials and related chemical waste, aligning with the United Nations Sustainable Development Goal 6, which promotes clean water and sanitation. For instance, cost-effective methods using enzymes or microbes can aid in processing the fibers and their associated dyeing solutions while also addressing textile wastewater, which contains high concentrations of unreacted dyes, salts, and other highly water-soluble pollutants. This paper covers different aspects of fiber chemistry, dyeing, degradation mechanisms, and the chemical waste produced by the textile industry, while highlighting microbial-based strategies for waste mitigation. The integration of microbes not only offers a solution for managing large volumes of textile waste but also paves the way for sustainable technologies. Full article
(This article belongs to the Special Issue Reactive and Functional Biopolymers)
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28 pages, 8366 KiB  
Article
Artificial Neural Network Modeling of Mechanical Properties of 3D-Printed Polyamide 12 and Its Fiber-Reinforced Composites
by Catalin Fetecau, Felicia Stan and Doina Boazu
Polymers 2025, 17(5), 677; https://doi.org/10.3390/polym17050677 - 3 Mar 2025
Cited by 2 | Viewed by 1558
Abstract
Fused filament fabrication (FFF) has recently emerged as a sustainable digital manufacturing technology to fabricate polymer composite parts with complex structures and minimal waste. However, FFF-printed composite parts frequently exhibit heterogeneous structures with low mechanical properties. To manufacture high-end parts with good mechanical [...] Read more.
Fused filament fabrication (FFF) has recently emerged as a sustainable digital manufacturing technology to fabricate polymer composite parts with complex structures and minimal waste. However, FFF-printed composite parts frequently exhibit heterogeneous structures with low mechanical properties. To manufacture high-end parts with good mechanical properties, advanced predictive tools are required. In this paper, Artificial Neural Network (ANN) models were developed to evaluate the mechanical properties of 3D-printed polyamide 12 (PA) and carbon fiber (CF) and glass fiber (GF) reinforced PA composites. Tensile samples were fabricated by FFF, considering two input parameters, such as printing orientation and infill density, and tested to determine the mechanical properties. Then, single- and multi-target ANN models were trained using the forward propagation Levenberg–Marquardt algorithm. Post-training performance analysis indicated that the ANN models work efficiently and accurately in predicting Young’s modulus and tensile strength of the 3D-printed PA and fiber-reinforced PA composites, with most relative errors being far less than 5%. In terms of mechanical properties, such as Young’s modulus and tensile strength, the 3D-printed composites outperform the unreinforced PA. Printing PA composites with 0° orientation and 100% infill density results in a maximum increase in Young’s modulus (up to 98% for CF/PA and 32% for GF/PA) and tensile strength (up to 36% for CF/PA and 18% for GF/PA) compared to the unreinforced PA. This study underscores the potential of the ANN models to predict the mechanical properties of 3D-printed parts, enhancing the use of 3D-printed PA composite components in structural applications. Full article
(This article belongs to the Special Issue 3D Printing of Polymer Composite Materials)
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25 pages, 4688 KiB  
Article
Enhancing Mechanical and Thermal Performance of Recycled PA6/PP Blends: Chain Extension and Carbon Fiber Reinforcement Synergy
by Neslihan Ergun, Mustafa Oksuz and Aysun Ekinci
Materials 2025, 18(5), 1027; https://doi.org/10.3390/ma18051027 - 26 Feb 2025
Cited by 1 | Viewed by 967
Abstract
To develop novel materials through the recycling of waste polymers and to enhance their mechanical and thermal properties, composites were synthesized using chain extenders (CEs), compatibilizers (PP-g-MA), and short carbon fiber (CF) reinforcements within recycled polyamide 6 (rPA6) and polypropylene (rPP) blends. The [...] Read more.
To develop novel materials through the recycling of waste polymers and to enhance their mechanical and thermal properties, composites were synthesized using chain extenders (CEs), compatibilizers (PP-g-MA), and short carbon fiber (CF) reinforcements within recycled polyamide 6 (rPA6) and polypropylene (rPP) blends. The recycling of waste polymers holds paramount importance in the context of environmental sustainability. This study investigates the role of additives in effectively improving the properties of recycled polymers. The composites were fabricated using the twin-screw extrusion method and subjected to a comprehensive range of characterizations, including Fourier Transform Infrared Spectroscopy (FTIR), differential scanning calorimetry (DSC), molecular weight analysis, melt flow index (MFI), heat deflection temperature (HDT), tensile testing, impact testing, and Scanning Electron Microscopy (SEM). Additionally, ANOVA statistical methods were applied to analyze HDT, tensile, and impact test results. The findings of this research demonstrate that chain extenders and compatibilizers significantly enhance the mechanical properties of rPA6/rPP blends, while carbon fiber reinforcements markedly improve both tensile strength and impact resistance. Furthermore, the incorporation of rPP led to an approximately 4% reduction in hardness values; however, this loss was effectively compensated by the addition of chain extenders and CF reinforcements, resulting in an overall increase in hardness. It was observed that chain extenders enhanced the elastic modulus and tensile strength by reinforcing interphase bonding, whereas CF reinforcements strengthened the polymer matrix, leading to improved impact resistance. These findings emphasize the synergistic role of chain extenders, compatibilizers, and CF reinforcements in enhancing the mechanical properties of rPA6/rPP blends. The study underscores recycling as both an environmentally beneficial and effective strategy for developing durable, high-performance composites for industrial use. Consequently, the utilization of recycled polymers contributes substantially to the circular and sustainable materials economy, demonstrating the potential for the widespread industrial adoption of such composites. Full article
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15 pages, 2932 KiB  
Article
Microstructural and Magnetic Properties of Polyamide-Based Recycled Composites with Iron Oxide Nanoparticles
by Lucas G. Dos Santos, Daina D. A. Buelvas, Daniel F. Valezi, Bruno L. S. Vicentin, Christian M. M. Rocha, Eduardo Di Mauro and Felipe de A. La Porta
Magnetism 2025, 5(1), 5; https://doi.org/10.3390/magnetism5010005 - 25 Feb 2025
Cited by 2 | Viewed by 1978
Abstract
This study explores a sustainable approach to developing magnetic nanocomposites by synthesizing a mixed-phase iron oxide (IO) and recycled polyamide (RPA) composite from textile waste. The RPA/IO nanocomposite’s microstructural and magnetic properties were characterized using X-ray diffraction (XRD) with Rietveld refinement, scanning, transmission [...] Read more.
This study explores a sustainable approach to developing magnetic nanocomposites by synthesizing a mixed-phase iron oxide (IO) and recycled polyamide (RPA) composite from textile waste. The RPA/IO nanocomposite’s microstructural and magnetic properties were characterized using X-ray diffraction (XRD) with Rietveld refinement, scanning, transmission electron microscopy (SEM, TEM), and vibrating sample magnetometry (VSM). The proportions of the Fe3O4 and γ-Fe2O3 phases were found to be 23.2 wt% and 76.8 wt%, respectively. SEM and TEM showed a porous, agglomerated IO surface morphology with an average particle size of 14 nm. Magnetic analysis revealed ferrimagnetic and superparamagnetic behavior, with VSM showing saturation magnetization values of 21.81 emu g−1 at 5 K and 18.84 emu g−1 at 300 K. Anisotropy constants were estimated at 4.28 × 105 and 1.53 × 105, respectively, for IO and the composite, with a blocking temperature of approximately 178 K at 300 K. These results contribute to understanding the magnetic behavior of IO and their nanocomposites, which is crucial for their potential applications in emerging technologies. Full article
(This article belongs to the Special Issue Magnetism and Correlations in Nanomaterials)
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16 pages, 5216 KiB  
Article
A New Approach Using Multi-Layer Films from Food Waste as a Shrink Film
by Kateřina Plevová, Michael Feuchter, Nadine Wild and Katharina Resch-Fauster
Processes 2025, 13(2), 560; https://doi.org/10.3390/pr13020560 - 17 Feb 2025
Cited by 2 | Viewed by 711
Abstract
Multi-layer films are one of the most challenging classes of polymer waste for recycling, as they consist of a mixture of constituent materials like polyethylene (PE), polyamide 6 (PA6), and ethylene vinyl alcohol (EVOH). This study investigates the characterization, washing, and mechanical properties [...] Read more.
Multi-layer films are one of the most challenging classes of polymer waste for recycling, as they consist of a mixture of constituent materials like polyethylene (PE), polyamide 6 (PA6), and ethylene vinyl alcohol (EVOH). This study investigates the characterization, washing, and mechanical properties of recycled blends derived from such multi-layer films. Raman spectroscopy and Differential Scanning Calorimetry (DSC) were used to characterize the individual components in single- and multi-layer films, and distinct properties of LDPE, LLDPE, PA6, and EVOH were observed. Mechanical properties enhanced by proper shredding, washing procedures, and multiple combinations of polyethylene blends were investigated to optimize the mechanical characteristics of the recycled materials, especially strain at break. Additionally, the shrinkage behavior of the recycled films was compared to commercial shrink films, demonstrating their potential for use in industry packaging applications. These results highlight a more sustainable possibility for multi-layer packaging applications. Full article
(This article belongs to the Special Issue Advances in Value-Added Products from Waste)
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18 pages, 15043 KiB  
Article
Use of Domestic Polymeric Waste for Surfactant Removal from Wastewater
by Thaiara Ramires dos Reis, Donizeti Leonardo Mancini Tolari, Ana Claudia Pedrozo da Silva, Elton Guntendorfer Bonafé, Rafael Block Samulewski and André Luiz Tessaro
Sustain. Chem. 2025, 6(1), 6; https://doi.org/10.3390/suschem6010006 - 14 Feb 2025
Viewed by 1274
Abstract
This study addresses the environmental challenge of surfactant removal from wastewater, focusing on the increased surfactant use during the COVID-19 pandemic. Polymeric waste, specifically polyurethane (PU) and polyamide (PA), was repurposed for surfactant adsorption to mitigate these environmental impacts. Methods included preparing surfactant [...] Read more.
This study addresses the environmental challenge of surfactant removal from wastewater, focusing on the increased surfactant use during the COVID-19 pandemic. Polymeric waste, specifically polyurethane (PU) and polyamide (PA), was repurposed for surfactant adsorption to mitigate these environmental impacts. Methods included preparing surfactant solutions of sodium linear alkylbenzene sulfonate (LAS) and dodecyl pyridinium chloride (DPC) and the mechanical processing of polymeric residues. PU and PA were characterized by FTIR-ATR and by the pH at the point of zero charge, which yielded pH = 8.0 for both polymers. The adsorption efficiency was optimized using a central composite face-centered design, varying pH, temperature, and time. The results indicated that PU and PA effectively adsorbed anionic and cationic surfactants, with specific conditions enhancing performance. From the optimized experimental conditions, four assays were carried out to evaluate the adsorption isotherms and kinetics. Among the fitted models, the SIPS model was the most representative, indicating a heterogeneous surface. Regarding LAS, the maximum adsorption capacity values were ~90 and 15 mg g−1, respectively, for PU and PA. Considering the DPC surfactant, lower values were obtained (~36 mg g−1 for PU and 16 mg g−1 for PA). The results are satisfactory because the adsorbents used in this study were second-generation waste and were used without treatment or complex modifications. The study concluded that using polymeric waste for surfactant removal offers a sustainable solution, transforming waste management while addressing environmental contamination. This approach provides a method for reducing surfactant levels in wastewater and adds value to otherwise discarded materials, promoting a circular economy and sustainable waste reuse. Full article
(This article belongs to the Special Issue Recycling and Upcycling of Plastic Wastes)
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11 pages, 686 KiB  
Review
Immobilization of Enzymes in Polymeric Materials Based on Polyamide: A Review
by Carolina E. Demaman Oro, Bruna M. Saorin Puton, Luciana D. Venquiaruto, Rogério Marcos Dallago and Marcus V. Tres
Processes 2025, 13(1), 200; https://doi.org/10.3390/pr13010200 - 13 Jan 2025
Viewed by 1507
Abstract
The immobilization of enzymes in polyamide-based polymeric materials through covalent bonding is an established technique to stabilize and reuse biocatalysts in industrial processes. Traditionally, enzymes are immobilized using crosslinking agents that activate functional groups on both the support and the enzyme, creating strong [...] Read more.
The immobilization of enzymes in polyamide-based polymeric materials through covalent bonding is an established technique to stabilize and reuse biocatalysts in industrial processes. Traditionally, enzymes are immobilized using crosslinking agents that activate functional groups on both the support and the enzyme, creating strong bonds that securely anchor the enzyme to the surface. While effective for maintaining enzyme activity over multiple cycles, this method can reduce catalytic efficiency due to rigid binding and involves complex activation steps. Recently, in situ immobilization approaches have emerged as promising alternatives. In this method, enzymes are directly entrapped within the polymer matrix during the synthesis of the polyamide support, such as nylon, simplifying the process and offering enhanced control over enzyme distribution. For instance, studies have demonstrated that in situ immobilization can improve enzyme stability by protecting it within the polymeric network, while reducing production costs and waste. This review explores the ability of polyamide as a support material for immobilization of enzymes, analyzing key techniques, performance across applications, and future strategies to optimize polymer-enzyme interactions for industrial use. Full article
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