Search Results (104)

Polyester–cotton (PES/CO) blends represent one of the most widely used textile classifications globally, yet their fibre-to-fibre recycling remains technically challenging due to the chemical dissimilarity of the two fibres. Existing reviews typically address textile recycling in broad terms, leaving a gap in critically evaluating the specific separation chemistries, recovered-fraction quality, and industrial maturity of PES/CO recycling routes. This review addresses that gap by providing a focused and comparative assessment of technologies designed for PES/CO fractionation. The paper analyses both polyester-removal and cellulose-removal routes, covering depolymerisation (hydrolysis, glycolysis, methanolysis, aminolysis), dissolving systems (NMMO, ionic liquids, DES, cold alkaline), and enzymatic or acid-based degradation. Each route is evaluated using technical criteria including fraction purity, cellulose degree of polymerisation, polyester monomer recovery, fibre quality, chemical consumption and energy requirement, solvent recovery, reaction conditions, and scalability. The review finds that chemical depolymerisation of PES and selective dissolution of cellulose currently show the strongest potential for high-quality fibre-to-fibre recycling, particularly when solvent recovery systems are integrated. However, significant barriers remain, including incomplete fraction purity, degradation of cellulose DP, limited recovery of high-quality polyester intermediates, high chemical consumption, and insufficient industrial-scale demonstrations. Overall, this review provides a differentiated and critical synthesis of PES/CO recycling technologies, clarifying their readiness levels and outlining the key scientific and industrial challenges that must be addressed to enable circularity in blended textile waste streams. Full article

Mixed cotton–polyester textile waste remains difficult to recycle because processes that recover synthetic polymers often leave the cotton fraction underused, while cellulose extraction methods may compromise the polyester component. This study investigates whether cotton in such blends can be converted into high-quality microcrystalline cellulose while retaining the potential value of the recovered polyester fraction. Cotton waste and cotton–polyester blends were treated using aqueous sulfuric acid at different conditions: from 15 to 20% acid concentration and from 70 to 80 °C for five to ten hours. The recovered microcrystalline cellulose was characterised and compared to commercial microcrystalline cellulose, while the polyester fraction was assessed using tensile testing. Enzymatic hydrolysis and a dimethyl sulfoxide co-solvent approach were evaluated as alternatives. The aqueous acid process yielded 82 to 97% microcrystalline cellulose from cotton waste and up to 51% from blended waste. The recovered cellulose showed around 10% higher crystallinity than commercial material and a similar particle size distribution, although morphology depended on the feedstock. The polyester fraction showed only minor reductions in tensile performance. The novelty of this study lies in the demonstration of a simple, ionic-liquid-free, single-reagent route that valorises both material streams from cotton–polyester textile waste. Full article

With the increasing generation of textile waste, efficient chemical recycling methods are urgently needed. This study evaluates a hydrochloric acid-based process for recycling polycotton textiles (polyester/cotton blends), in which cotton is selectively hydrolyzed and converted into 5-(chloromethyl)furfural (CMF), while polyester is recovered. The impact of common non-polycotton fiber contaminants on process performance and product quality was systematically assessed. Cellulose-based fibers did not hinder the process and are suitable for CMF production, while most synthetic fibers were effectively removed without affecting the CMF yield. In contrast, animal fibers reduced the CMF yield and complicated acid recovery, indicating they should be avoided in the feedstocks. Additionally, polyacrylonitrile and wool persisted in the solid fraction, contaminating the recovered polyester and lowering its value. To improve process robustness and product quality, intermediate filtration and extended hydrolysis time are recommended. These findings highlight critical feedstock requirements and operational adjustments for scalable polycotton recycling. Full article

The effect of reversible addition–fragmentation chain transfer (RAFT) polymerization on the structure, morphology, and thermal degradation behavior of polypropylene glycol maleate–acrylic acid copolymers (p-PGM:AA) was investigated using 2-cyano-2-propyl dodecyl trithiocarbonate (CPDT) as the RAFT agent. Copolymers synthesized at different CPDT concentrations were characterized by ¹H/¹³C NMR spectroscopy, gel permeation chromatography (GPC), transmission electron microscopy (TEM), thermogravimetric analysis coupled with mass spectrometry (TG–MS), isoconversional kinetic methods, and density functional theory (DFT) calculations. ¹H NMR spectroscopy revealed a progressive decrease in the relative intensity of vinyl proton signals with increasing CPDT concentration, indicating enhanced conversion of unsaturated fragments during copolymerization. Alkaline hydrolysis followed by ¹H NMR and GPC analysis of the degradation products confirmed cleavage of polyester segments and yielded low-molecular-weight fragments with M_n = 1370 g mol⁻¹ and narrow dispersity (Đ = 1.035), providing additional information on the architecture of the vinyl-polymerized segments. Increasing CPDT concentration resulted in lower molecular weights and narrower molecular weight distributions of the soluble copolymer fractions. TEM analysis demonstrated broader domain size distributions and increased morphological heterogeneity in RAFT-modified samples, accompanied by an increase in swelling degree. Thermogravimetric analysis showed that RAFT-modified systems undergo multi-stage thermal degradation with the appearance of an additional low-temperature stage associated with thermolabile fragments. TG–MS revealed earlier evolution of CO₂ and oxygen-containing species and changes in the distribution of volatile products. DFT calculations indicated a decrease in the HOMO–LUMO energy gap and suggested the participation of RAFT-derived fragments in the energetic characteristics of decarboxylation processes. Isoconversional and nonlinear kinetic analyses demonstrated increased kinetic heterogeneity for branched copolymer s synthesized at elevated CPDT concentrations, whereas cross-linked systems exhibited more uniform degradation behavior. The combined experimental and theoretical results demonstrate that RAFT polymerization provides an effective route for tuning the macromolecular architecture, morphology, and thermal degradation pathways of p-PGM:AA copolymers. Full article

Polyethylene terephthalate (PET) is one of the most widely used plastics for single-use applications, with annual global production exceeding 80 Mt. Enzymatic degradation of PET has emerged as a promising and sustainable alternative to conventional recycling methods, enabling the hydrolysis of PET into its constituent monomers. While amorphous PET can be efficiently degraded by polyester hydrolases identified from environmental sources, crystalline PET remains highly recalcitrant to enzymatic attack and constitutes a major bottleneck for the industrial implementation of enzymatic PET recycling. Although physicochemical pretreatments can increase PET amorphicity, these approaches often require substantial energy input, thereby compromising the overall sustainability of the process. Consequently, the development of enzymes capable of directly degrading crystalline PET has long been sought; however, currently engineered enzymes exhibit insufficient catalytic activity toward highly crystalline PET owing to multiple factors, including limited substrate surface accessibility, highly ordered polymer morphology, incompatible binding-pocket geometries, restricted chain mobility, and unfavorable conformational energetics at the polymer–enzyme interface. This review aims to evaluate the factors limiting the enzymatic degradation of crystalline PET and to assess current strategies for overcoming low degradation rates. Specifically, it examines advances in substrate modification as well as enzyme- and process-engineering approaches designed to improve the depolymerization of crystalline PET. The advantages and limitations of these strategies are critically compared and discussed, highlighting the remaining challenges and future directions toward efficient and scalable biocatalytic PET recycling. Full article

Plant pathogenic fungi seriously threaten global crop production, and endophytic fungi are promising reservoirs of bioactive antifungal metabolites. Three undescribed polyester derivatives, talapolyesters I–K (1–3), along with thirteen known compounds including 15G256ω (4), 15G256ι (5), 15G256α (6), talapolyester E (7), 15G256α-1 (8), 15G256α-2 (9), 15G256α-2-me (10), 15G256ν (11), ES-242-3 (12), dongtinganthracene A (13), penicillide (14), 3-methyl-6-hydroxy-8-methoxy-3,4-dihydroisocoumarin (15), and (R)-6-hydroxymellein (16), were isolated from the endophytic fungus Talaromyces striatoconidius WI-F2. Their chemical structures were elucidated comprehensively using NMR and MS spectroscopic analyses, combined with alkaline hydrolysis. Compounds 4–8 exhibited in vitro promising antifungal activity against Fusarium oxysporum f. sp. cubense, with half-maximal inhibitory concentration (IC₅₀) values of 9.72, 21.07, 7.89, 8.91 and 9.65 μg/mL respectively, all markedly lower than that of ketoconazole (46.23 μg/mL). Molecular docking simulations further validated the observed antifungal activity, with binding energies ranging from −9.01 to −12.25 kcal/mol, indicative of stronger binding affinity compared with benzamidine (−6.80 kcal/mol). This study offers new clues for research on antifungal agents. Full article

We report di- and triblock copolymers that combine hydrophilic polyethers—poly(ethylene glycol) monomethyl ether (mPEG) and polyglycidol (PGl)—with a hydrophobic, degradable polyester, poly(β-butyrolactone) (P(β-BL)). A mild hydrolysis method was developed to selectively remove acetal protecting groups from poly(ethoxy ethyl glycidyl ether) (PEEGE) without cleaving the β-butyrolactone polyester backbone, enabling the preparation of PGl-b-P(β-BL) and mPEG-b-PGl-b-P(β-BL) block copolymers. Thermal analysis revealed that the glass transition temperatures (T_g) of the copolymers could be tuned by varying block composition and length. Diblock copolymers containing the PGl segment were amorphous, with T_g values ranging from −2.7 to −19.9 °C. The presence of an mPEG segment in the triblock copolymers resulted in a further decrease in T_g, reaching values between −32.3 and −38.9 °C. Solubility and water affinity studies demonstrated that incorporation of hydrophilic polyether blocks enhances copolymer–solvent interactions, leading to increased wettability of the polymer-coated surface. The water contact angle for films formed from PGl-b-P(β-BL) decreased to 53 °C, while for mPEG-b-PGl-b-P(β-BL) copolymers, it was further reduced to 43 °C compared with the hydrophobic P(β-BL) film. Hydrolytic degradation experiments showed accelerated cleavage of the P(β-BL) segment in copolymers containing hydrophilic blocks compared to the P(β-BL) homopolymer, which is attributed to increased water accessibility and surface hydrophilicity. The most pronounced decrease in molar mass, reaching at least 50% relative to the initial non-degraded sample, was observed for the diblock copolymers, whereas the P(β-BL) sample showed only a marginal weight reduction of a few percent. Overall, this study demonstrates that the combination of hydrophilic mPEG and PGl blocks with P(β-BL) enables the design of block copolymers with tunable thermal properties, solubility, and degradation behavior, offering potential for a wide range of applications. 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

The global economy is increasingly faced with the challenge of accepting its responsibility for recycling polyester textile waste. With back-to-monomer recycling technologies, PET can be recycled to its monomers, terephthalic acid and ethylene glycol. The recycling of polyester-containing textiles requires the complete separation of all contaminating materials, dyes, and additives, which can only be achieved by depolymerization technologies. This article presents the adsorptive decolorization of a disodium terephthalate solution from the alkaline hydrolysis of polyester textile waste. The influence of different adsorbents, temperature (30–80 °C), and pH value (7–12) on the adsorptive decolorization process is investigated. As a result, activated carbons for decolorization have been identified. It was found that the adsorption process is favorable at neutral pH and a temperature of 80 °C. The findings show that a color value within the industrial specification can be obtained for recycled terephthalic acid using activated carbon adsorption. This adds a key step for high-quality textile-to-textile recycling and thus contributes to a circular economy for polyester. Full article

Polyester fibers are extensively used in textiles, packaging, and industrial applications due to their durability and excellent mechanical properties. However, high-crystallinity polyester fibers represent a major challenge in plastic waste management due to their resistance to biodegradation. This study evaluated the biodegradation potential of environmental Bacillus isolates, obtained from mold-contaminated black bean plastic bags, toward polyethylene terephthalate (PET) and industrial-grade polyester fibers under mesophilic conditions. Among thirteen isolates, five (Bacillus altitudinis N5, Bacillus subtilis N6, and others) exhibited measurable degradation within 30 days, with mass losses up to 5–6% and corresponding rate constants of 0.04–0.05 day⁻¹. A combination of complementary characterization techniques, including mass loss analysis, scanning electron microscopy (SEM), gel permeation chromatography (GPC), and gas chromatography/mass spectrometry (GC/MS), together with Fourier-transform infrared spectroscopy (FTIR), thermogravimetric/differential scanning calorimetry (TGA/DSC), and water contact angle (WCA) analysis, was employed to evaluate the biodegradation behavior of polyester fibers. Cross-analysis of mass loss, surface morphology, molecular weight reduction, and degradation products suggests a surface erosion-dominated degradation process, accompanied by ester-bond hydrolysis and preferential degradation of amorphous regions. FTIR, TGA/DSC, and WCA analyses further reflected chemical, thermal, and surface property changes induced by biodegradation rather than directly defining the degradation mechanism. The findings highlight the capacity of mesophilic Bacillus species to partially depolymerize polyester fibers under mild environmental conditions, providing strain resources and mechanistic insight for developing low-energy bioprocesses for polyester fiber waste management. Full article

Polyethylene terephthalate (PET) recycling technology has developed into a mature system, providing a key paradigm for the circular utilization of polyester waste. Its pathways are primarily divided into mechanical recycling and chemical recycling. Mechanical recycling converts waste PET into rPET through physical processes such as efficient sorting, deep cleaning, and melt extrusion. However, the resulting product often faces issues of decreased intrinsic viscosity and thermal oxidative degradation. Chemical recycling, particularly depolymerization techniques like saccharification, hydrolysis, and methanolysis, can reduce PET waste back to monomers. After purification, these monomers can be repolymerized into virgin-quality PET, achieving a closed-loop cycle. However, this approach faces challenges related to cost and process complexity. Against this backdrop, this paper further explores potential recycling methods for polyethylene terephthalate-1,4-cyclohexanedimethyleneterephthalate (PETG). This paper argues that the experience of PET recycling provides a crucial foundation for addressing PETG challenges but is not a direct solution. Future development directions include: developing intelligent sorting technologies, creating highly efficient selective catalysts to optimize depolymerization reactions, and other initiatives. These measures are essential for establishing an efficient recycling system for complex polyester waste. Full article

Plugging materials play a crucial role in oil production. Current development of temporary plugging agents still faces challenges such as insufficient sealing strength, poor temperature resistance, and complex manufacturing processes. To enable barrier materials for higher-temperature applications, we extensively studied the hydrolysis processes of aliphatic polyesters, polyamides, and thermosetting resins at different temperatures, analyzing the hydrolysis mechanisms of representative poly (butylene terephthalate) (PBT) and polyamide 6 (PA6). Inspired by the etching effect inspired by wood decay under humid environments, PBT was selected as the continuous phase to design and prepare a PBT/PA6 blend exhibiting physicochemical synergistic effects. The results indicate that PBT/PA6 blends exhibit significantly faster hydrolysis characteristics at 120 °C compared to pure thermoplastic polyesters. We found this to be the result of a synergistic effect where the terminal amine groups released during PA6 hydrolysis catalyze PBT hydrolysis, while the etching effect of the PBT continuous phase during hydrolysis accelerates PA6 hydrolysis. This study innovatively integrates physical–chemical synergistic effects, proposing a material design strategy that significantly enhances degradation rates. Full article

This study demonstrates the valorization of orange peel waste as a sustainable feedstock for the production of cellulose nanocrystals (CNCs). Compositional analysis revealed a cellulose content up to 10.0% in the raw material. After performing the alkaline/peroxide treatment, CNCs were isolated via acid hydrolysis. Different inorganic acids were compared, namely sulfuric, phosphoric, and hydrochloric acids at low molar concentrations. The resulting CNCs showed distinct morphological and physicochemical properties, with sulfuric acid treatment yielding the highest crystallinity index (TCI) of 0.86 under conditions of 3.0 mol/L, 80 °C, and 225 min. Additionally, the presence of sulfate or phosphate groups significantly influenced the thermal degradation behavior and the inorganic residue content in the obtained CNCs. Finally, the CNCs were successfully tested as co-initiator for lactide ring-opening polymerization. The results show that the molecular weights of the resulting polylactide varied depending on the CNC dispersion. This work supports the use of orange peel waste as a bio-source for CNC production and their potential application as a co-initiator in the synthesis of polyesters. Full article

The inherent hydrophobic nature of PVDF material renders it challenging to establish a stable aqueous hydration layer, thereby limiting its suitability as a substrate for the preparation of nanofiltration (NF) membranes. In this study, we developed a novel modification approach that effectively enhances the hydrophilicity of PVDF substrates through the incorporation of sulfonic acid-doped polyaniline (SPANI) and hyperbranched polyester (HPE) into the PVDF casting solution, followed by cross-linking with trimesoyl chloride (TMC). The introduction of SPANI and HPE, which contain reactive polar amino and hydroxyl groups, improved the hydrophilicity of the substrate, while the subsequent cross-linking with TMC effectively anchored these components within the substrate through the covalent linking between TMC and the reactive sites. Additionally, the hydrolysis of TMC yielded non-reactive carboxyl groups, which further enhanced the hydrophilicity of the substrate. As a result, the modified PVDF substrate exhibited improved hydrophilicity, facilitating the construction of an intact polyamide layer. In addition, the fabricated TFC NF membrane demonstrated excellent performance in the advanced treatment of tap water, achieving a total dissolved solid removal rate of 57.9% and a total organic carbon removal rate of 85.3%. This work provides a facile and effective route to modify PVDF substrates for NF membrane fabrication. Full article

This study systematically investigates the impact of hydrolytic degradation on the crystallization kinetics and morphology of poly(butylene succinate-co-adipate) (PBSA). Gel Permeation Chromatography (GPC) confirmed extensive chain scission, significantly reducing the polymer’s weight-average molecular weight (M_w from ~103,000 to ~16,000 g/mol) and broadening its polydispersity index (PDI from ~2 to 7 after 64 days). Differential scanning calorimetry (DSC) analysis revealed that hydrolytic degradation dramatically accelerated crystallization rates, reducing crystallization time roughly 10-fold (e.g., from ~3000 s to ~300 s), and crystallinity increased from 34% to 63%. Multiple melting peaks suggested the presence of lamellae with varying thicknesses, consistent with the Gibbs–Thomson equation. Isothermal crystallization kinetics were evaluated using the Avrami equation (with n ≈ 3), reciprocal half-time of crystallization, and a novel inflection point slope method, all confirming accelerated crystallization; for instance, the slope increased from 0.00517 to 0.05203. Polarized optical microscopy (POM) revealed evolving spherulite morphologies, including hexagonal and flower-like dendritic spherulites with diamond-shape ends, while wide-angle X-ray diffraction (WAXD) showed a crystallization range shift to higher temperatures (e.g., from 72–61 °C to 82–71 °C) and a 14% increase in crystallite diameter, aligning with increased melting point and lamellar thickness and overall increased crystallinity. Full article