Search Results (227)

Accurate quantification of cotton content is a key prerequisite for efficient textile recycling. However, it remains challenging due to material heterogeneity and technical limitations. Near-infrared spectroscopy (NIR) combined with advanced data analysis offers a rapid, non-destructive approach. However, systematic evaluations across instrument classes and analysis strategies for industrial textile sorting remain limited. In this study, a unique set of cotton/polyester blends from the same starting material with varying cotton content was analyzed using three NIR systems representing laboratory, handheld, and industrial sensor-based applications. Multiple spectral preprocessing strategies were systematically combined with partial least squares regression and advanced machine learning models. Model performance was evaluated using cross-validation and independent test sets. The benchtop NIR system delivered the highest and most consistent performance, achieving RMSEP values below 1.0% with advanced regression models. The handheld and imaging sensor system exhibited higher RMSEP values (1.2–1.6%), reflecting not only differences in preprocessing and model selection, but also intrinsic instrumental limitations. Overall, the results demonstrate that each NIR instrument class exhibits distinct strengths and limitations with respect to accuracy, sensitivity, and robustness. Consequently, instrument-specific preprocessing, models, and hyperparameters are required, and no universally transferable pipeline was identified. Full article

The growing volume of fiber-reinforced polymer composite waste creates an urgent need for efficient recycling technologies. While solvolysis effectively breaks down thermoset matrices for fiber reinforcement recovery, the process generates hydrocarbon-rich liquid by-products that require further management. This study validates the use of these liquid recycling streams—derived from the solvolysis of unsaturated polyester and epoxy resins—as sustainable carbon precursors for the growth of carbon nanomaterials. Synthesis was performed via catalytic chemical vapor deposition (CVD) at 850 °C using iron nanoparticles impregnated on a zeolite substrate. Morphological analysis confirmed the production of one-dimensional nanostructures (carbon nanotubes/nanofibers), with average diameters below 100 nm. Raman spectroscopy revealed a high degree of graphitization, with I_D/I_G ratios ranging from 0.25 to 0.58, which is comparable to structures synthesized from conventional precursors. Thermogravimetric analysis (TGA) demonstrated high thermal stability and carbon purity reaching up to 90.3%. These findings demonstrate a viable upcycling pathway that enhances the economic attractiveness of composite recycling by transforming waste into advanced nanomaterials. Full article

The conducted study was focused on the development of a new type of polymer blends intended for additive manufacturing applications, in particular, the material extrusion method (MEX). The developed materials were prepared from recycled poly(ethylene terephthalate) and amorphous copolymers poly(ethylene terephthalate-glycol) (PETG), and poly(cyclohexylenedimethyl terephthalate-glycol) (PCTG). The basic blend systems were additionally modified with POE-g-GMA impact modifier (IM) during the reactive extrusion process. The main aim of the work was to assess the effectiveness of using composite additives and their influence on the mechanical and thermomechanical parameters of the tested systems. To prepare the composites, selected polymer blends were modified with 10% of talc (T) and carbon fibers (CF). The properties evaluation includes the mechanical/thermomechanical testing, thermal analysis and structural observations. The accuracy of printing was measured using optical scanning methods. The test results indicate that even the relatively small amount of the CF filler could lead to a significant increase in tensile modulus from reference 1.6 GPa to 2.9 GPa; the same improvement applies to strength values, where the CF-modified materials reached 45 MPa, compared to the reference 31 MPa. The heat deflection tests (0.455 MPa) after annealing revealed the maximum HDT of around 170 °C for both types of CF-modified materials. The Vicat test results were also favorable for annealed materials. Considering that the Vicat/HDT results after the 3D-printing process usually reach around 70 °C, the performed heat treatment strongly enhanced the heat resistance for most of the prepared blends. The performed studies revealed that for most of the prepared materials, the brittleness was a common drawback for both MEX-printed and injection-molded materials. Full article

Indonesia, as a major global textile exporter, faces substantial sustainability challenges due to its linear production model, which generates massive volumes of post-industrial polyester waste (PIPW). However, reliable data and recycling pathways remain critically lacking. This study quantifies the volume, composition, and textile-to-textile (T2T) recyclability potential of PIPW across Indonesia’s national textile and clothing production chain, employing a mixed-methods approach that integrates material flow analysis (MFA), site visits, and stakeholder interviews. The results indicate that 572 kilotonnes of PIPW were generated in 2023, with garment manufacturing identified as the most waste-intensive. Nineteen waste types were identified; 61% comprise fibre blends, which significantly constrain closed-loop recycling. A novel five-tier waste typology was developed to classify waste streams based on material characteristics, technological availability, and economic feasibility. The circularity map reveals that Indonesia is trapped in pseudo-circularity. Scenario analysis suggests that up to 184 kilotonnes of PIPW could be feasibly redirected towards higher-value chemical recycling. The research recommends mandatory source segregation, fiscal incentives, investment in chemical recycling infrastructure, and the integration of circular design into national standards. The study provides the first national-level MFA of PIPW in Indonesia and establishes an empirical baseline to advance T2T recycling in emerging economies. Full article

Advances in Industry 4.0 manufacturing have accelerated the adoption of machine learning (ML) for automated classification. Polyester (PES), a widely used synthetic fiber, competes with natural fibers like cotton and other synthetics, highlighting the need for continuous research and improvement. In the textile sector, distinguishing recycled polyester (rPES) from virgin polyester (vPES) remains challenging due to overlapping chemical signatures and material variability. A combination of Fourier transform infrared (FTIR) spectroscopy and ML has not been explored for this purpose. In this study, we evaluated ML models to discriminate three PES fiber types (45 vPES, 65 rPES, and 55 mixed PES) using 165 FTIR spectra across four spectral regions, R1, R2, R3, and R4, as well as their combined representation. Six ML approaches were tested on data reduced with fast independent component analysis (FastICA) (1–30 components) using an 80/20 train–test dataset split. The Decision Tree classifier achieved the highest Accuracy in four of the five spectral evaluations, with classification accuracies ranging from 66.67% to 77.78% for region R4, which also had a balanced classification profile with an area-under-the-curve (AUC) value of 0.81. Notably, despite the moderate overall Accuracy, the model achieved 100% discrimination of rPES when distinguishing it from both mixed and vPES. Mixed fibers remained the most difficult to classify, highlighting the need for improved feature representation. Full article

Polyethylene terephthalate (PET) plays a pivotal role in the chemical fiber industry, constituting over 50% of fiber consumption. However, the reduction of the recycled fiber-derived viscosity of the PET significantly impacts its spinning performance and restricts its closed-loop recycling to high-value regenerated fibers. To address these limitations, this study explored the viscosity improvement of black and white waste fiber-derived polyester particles through a two-step process involving micro-glycolysis and self-polycondensation. Initially, a continuous micro-glycolysis of fiber-derived PET was carried out in a twin-screw extruder with ethylene glycol (EG), which effectively cleaves the ester bonds in the PET chains, generating oligomers with reactive hydroxyl end groups. Subsequently, these oligomers were repolymerized without purification, and a higher molecular weight regenerated PET with enhanced intrinsic viscosity was obtained with antimony ethylene glycolate (Sb-EG) as a catalyst. The results revealed that the intrinsic viscosity decreased exponentially with increasing EG dosage during glycolysis, reaching approximately 50% of the initial value at 0.2–2 phr EG dosages. Optimal viscosity enhancement was achieved at a polycondensation time of 1–3 h, resulting in improved thermal stability and reduced crystallization temperatures. Importantly, regenerated PET samples with EG dosages of ≤2 phr demonstrated intrinsic viscosities of about 0.70 dL/g, meeting the standard for spin-grade polyester fiber, which is used to produce regenerated polyester fibers. This recycling process is low cost, environmentally friendly, and easy to scale-up, contributing significantly to the development of industrial recycling of waste polyester fabrics. Full article

5-Methoxymethyl-2-furfural (MMF) serves as a crucial biobased platform molecule that can be transformed into various high-value chemicals and biobased polyester monomers. However, the current production of MMF still faces several challenges, such as low yield and prolonged reaction time. In this study, we prepared a series of amide-modified strongly acidic resin catalysts and discovered that they have a higher efficiency in converting fructose to prepare MMF in 1-Butyl-3-methylimidazolium chloride ([BMIM]Cl) and methanol. Among the synthesized catalysts, DB757-NMP demonstrated superior performance, achieving an MMF yield of approximately 61.5% under the optimized conditions, with a combined yield of HMF and MMF reaching about 66.6%. The catalyst formation mechanism was analyzed using FTIR, and NMR, confirming the transformation of proton between NMP and the sulfonic acid groups of the resin, which collectively promoted the conversion of fructose to MMF. In addition, we investigated main reasons for catalyst deactivation and successfully restored catalytic activity through regeneration. The regenerated catalyst could be reused for three times with only a slight decrease in MMF yield. The results suggested that DB757-NMP is a more sufficient and recyclable catalyst for the production of MMF from fructose. This work presented a simple and environmentally benign approach for the synthesis of MMF. Full article

The textile industry faces significant challenges regarding the need for textile waste recycling. This study investigates the feasibility of alkaline hydrolysis assisted by alcoholic co-solvents, such as ethanol, for recycling polyester/cotton blend textiles. Ethanol-assisted alkaline hydrolysis under mild conditions enabled almost complete depolymerisation of polyester, allowing the recovery of its monomers, terephthalic acid and ethylene glycol, which may be used to produce new polyester fibre. However, the treatment was found to adversely affect the properties of the cotton fibres, resulting in a recycled material of lower quality and functionality than the original material. In particular, a significant change in the structure of the cotton fibre was observed, namely, the transformation of cellulose I into cellulose II, as confirmed by FTIR analysis, along with a decrease in both the degree of polymerization and tensile strength, especially at an ethanol/water ratio of 40/60. Hence, alcohol-assisted alkaline hydrolysis is advisable for the chemical recycling of polyester, but it presents limitations when cotton fibres are also present. Full article

Reducing dependence on fossil-based feedstocks for packaging can be achieved through three complementary strategies: minimizing packaging use, increasing closed-loop recycling rates, and expanding the adoption of renewable (e.g., biobased) packaging materials. To ensure these defossilization pathways reinforce rather than hinder one another, it is essential to understand how new biobased materials interact with existing recycling streams. With the market introduction of packaging containing the biobased polyester poly(ethylene 2,5-furandicarboxylate) (PEF) approaching, several studies have investigated blends and copolyesters of poly(ethylene terephthalate) (PET) and PEF. This study expands current knowledge of thermomechanical and crystallization behavior by examining the influence of PEF on the mechanical recycling process of bottle-grade PET. Processing behavior was assessed at various PEF contents at both laboratory and industrial scales, and the resulting recycled resin and bottles were analyzed for color, crystallization behavior, and bottle performance. Although the melting temperature decreased with rising PEF content, no negative impact on the industrial recycling process investigated was observed for PEF levels up to 10 wt%. Two notable trends emerged: increasing PEF content reduced crystallization rate, yielding bottles with higher transparency, while yellowness also increased. Ongoing research aims to understand and mitigate this rise in yellowness. Full article

Textile-to-textile recycling is increasingly recognised as essential to reduce the environmental footprint of the textile sector, yet fibre-to-fibre routes remain constrained by complex composition of fibre blends, chemical finishes and the degradation of fibre quality during repeated processing. This review provides a comprehensive overview of recycling strategies for major textile fibres, cotton, polyester, viscose, polyamide, and wool, from a fibre-level perspective, highlighting the relationships between fibre chemistry, structure, and recyclability. Mechanical, chemical, and biological recycling routes are analysed with a particular focus on fibre integrity, yarn and fabric performance, and their suitability for industrial textile applications rather than solely on waste management aspects. The review also examines industrial initiatives and emerging technologies driving the transition towards circular textile systems, critically identifying key barriers such as feedstock heterogeneity, fibre blending, and downcycling. Building on existing review articles on textile recycling, this work synthesises current knowledge on fibre-to-fibre routes, compares different process options in terms of recycled-fibre quality and scalability, and highlights remaining technological and implementation gaps. To advance textile circularity, integrated recycling frameworks are proposed that align material design, process optimisation, and policy instruments. This work contributes a cross-disciplinary understanding of how fibre-level innovation can enable resource-efficient, closed-loop textile production, offering a roadmap for future sustainable materials engineering in industrial textile systems. Full article

Elastane is ubiquitous in polyester-based textiles and complicates depolymerization-based recycling because it can undergo thermal degradation and chemical bond cleavage, consuming reagents and forming low-molecular by-products that may compromise monomer quality. Here, we investigate alkaline PET depolymerization of PET/elastane blends under an intentional base-competition scenario in a laboratory kneader. Pure PET (100/0) and PET/EL blends (95/5 and 85/15, wt/wt) were processed under quasi-solid-state conditions at 140 °C for 5 min using solid NaOH dosed at 2.1 mol per mol PET repeat unit and pelletized feedstocks to ensure scale-relevant mixing and reproducible chamber filling. Torque and bulk-temperature profiles were similar across compositions, and isolated terephthalic acid yields remained in a narrow corridor (68–71%), indicating that PET depolymerization is not measurably impaired by 5–15 wt% elastane within this reaction window. Differential scanning calorimetry of water-insoluble residues revealed pronounced changes in elastane-related thermal transitions, evidencing elastane modification during treatment. Targeted ¹H NMR screening of recovered TA against a 4,4′-methylenedianiline spiked reference showed no detectable co-isolated aromatic diamines. Overall, the study demonstrates robust monomer recovery from mixed PET/EL textiles under solid-NaOH, short-residence, solvent-lean processing, while identifying residue analytics as the key bottleneck for quantifying elastane fate and closing component balances. Full article

Despite the enormous amounts of waste textiles produced by the world’s textile industry’s explosive growth, resource utilization rates are still poor. Cotton/polyester blended waste fabrics make up a sizable share, and sorting them precisely is essential to increasing recycling value and promoting the circular economy in the textile industry. Traditional mechanical and human sorting techniques are ineffective and inaccurate; current spectral analysis algorithms mainly concentrate on quantitative composition prediction and are insufficiently capable of differentiating between waste fabrics with comparable content gradients. To address these challenges, this paper proposes an improved 1DCNN model (Dual-1DCNN-Residual-SE) integrated with Near-Infrared (NIR) hyperspectral imaging technology. This model takes raw spectral data and Savitzky-Golay (SG) smoothing data as dual-channel inputs, introducing residual connections to capture subtle spectral differences between similar fabric categories, and employs SE attention mechanisms to adaptively enhance key features. Comparative experiments with four traditional algorithms—KNN, RF, SVM, and PLS—demonstrate that the proposed model achieves a classification accuracy of 95.94%, surpassing the best traditional algorithm SVM (88.12%) by 7.82%. Ablation experiments confirm each enhanced module’s efficacy. This study achieves high-precision classification of cotton/polyester blended waste fabrics, providing technical support for intelligent sorting of industrial waste fabrics. Full article

The growing environmental impact of conventional textile dyeing processes, particularly their high water consumption, chemical usage, and wastewater generation, has intensified the need for alternatives. For this reason, the textile industry faces increasing pressure to adopt sustainable production routes that minimize environmental loads. The utilization of recycled polyester fabrics, natural dyes, and waste-derived bio-resources within waterless dyeing systems represents a holistic approach toward environmentally responsible textile manufacturing. This study focuses on the production of sustainable textiles by dyeing recycled polyester fabrics with natural madder dye and eggshell powder in a waterless supercritical CO₂ medium. The samples were characterized via SEM, TGA, wash fastness tests, and tensile strength measurements. SEM images clearly revealed the presence of eggshell powder (ESP) on the fabric surfaces. After UV aging, the samples containing 20% ESP exhibited higher tensile strength and more pronounced color stability compared to the control sample. The CaCO₃ component of the ESP contributed to UV resistance, while the TGA results showed higher residual mass for ESP-treated samples, indicating improved thermal stability. Moreover, the persistence of ESP on the fabric surface after repeated washing and the satisfactory wash fastness results confirmed the durability of the treatment. Overall, the results demonstrate that the combination of natural dye, recycled polyester, and eggshell-derived bio-additives in a waterless scCO₂ dyeing system offers a promising and environmentally benign strategy for producing sustainable and functional textile materials. Full article

This work investigates the effect of recycling on the rheological and thermal properties of petroleum-based polyester nanocomposites. PET and PBT are used widely in the automobile and packaging industries, and there is a growing need for effective ways to utilize recycled polyesters. The melt mixing method was used to prepare the nanocomposites using a twin-screw extruder. After recycling, the rheological properties of the PBT nanocomposite remained stable, as the degradation of PBT chain was low due to the presence of MWCNT and molecular chain flexibility. In contrast, the complex viscosity of PET recycled nanocomposite decreases significantly because the high processing temperature of 280 °C led to substantial polymer chain scission and network breakdown. Due to the presence of MWCNT, PET and PBT nanocomposites show higher thermal stability than pure and recycled nanocomposites. The recycling of PET and PBT nanocomposites demonstrated potent thermal stability under inert and air/oxidative atmospheres. These results indicate that the effect of recycling strongly depends on the polymer matrix: while PET-based nanocomposites exhibit notable reductions in rheological properties after recycling, PBT-based nanocomposites retain stable rheological and thermal performance due to MWCNT reinforcement. The enhancement in this research could make the recycled materials valuable for the automotive industry. Full article

This study investigated the chemical recycling of poly(ethylene terephthalate) (PET) fiber residues from two sources—high-molar mass mooring ropes and low-molar mass textile-grade fibers—to produce functional oligomers. Glycolysis was carried out using polyethylene glycol (PEG400) as the depolymerizing agent, and two catalysts were assessed, zinc acetate and lithium octoate, with the latter reported on for the first time in this application. Reactions were performed for 180 min under mechanical stirring, inert atmosphere, reflux, and controlled heating. The resulting oligomers were characterized by Fourier-transform infrared spectroscopy (FTIR), hydroxyl and acidity indices, and thermogravimetric analysis (TGA). Both PET feedstocks showed high reactivity toward glycolysis. Monitoring the reactions by acidity index indicated that conversion reached equilibrium at approximately 120 min. ATR-FTIR confirmed the formation of ester and hydroxyl groups, consistent with oligomer structures. Glycolysis of PET derived from mooring ropes produced oligoesters with hydroxyl values of 228 and 242 mgKOH/g for zinc acetate and lithium octoate, respectively, and molar masses of 1296 and 1338 g/mol for zinc acetate and lithium octoate, respectively. These values are suitable for subsequent syntheses such as polyester polyol production. Full article