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Abstract The combination of phase change materials (PCMs) with fibers can afford smart fibers with thermal management properties. However, the issues of easy leakage and poor thermal stability of PCMs [...]

Improving the flame retardant performance of polycaprolactam (PA6) will greatly expand its applications. At present, the commonly used reactive flame retardants of PA6 mainly come from the petrochemical industry. Therefore, D-glucopyranose, a green renewable biomass, is selected and bonded to the PA6 molecular chain through in situ polymerization to obtain a series of flame retardant polyamides (PA6/G1) and their high-speed melt-spun fibers. When its added amount was 2 wt%, the LOI and UL-94 of PA6/G1 reached 29.4 Vol% and V-0 level, and the char residue was 529.4% higher than that of neat PA6 after thermogravimetric test. D-glucopyranose contains a polyhydroxy structure that can capture the hydrogen radicals generated by homogeneous cracking during combustion, increasing the content of C[O.sub.2] and [H.sub.2]O and forming a smooth and dense carbon isolation layer. Thus, the synergistic flame retardant effect of green D-glucopyranose on the gas and condensed phases of PA6 is achieved. KEYWORDS D-glucopyranose, fiber, flame retardant, polyamide 6, 1 | INTRODUCTION Polycaprolactam (PA6) fiber refers to a type of synthetic fiber whose molecular chain is connected by amide bonds (--CO--NH--), and is the second synthetic fiber to realize [...]

In response to an investigation on the paths of changes in the crystallization and radial differences during the forming process of nascent fibers, in this study, we conducted numerical simulation and analyzed the changes in crystallization mechanical parameters and tensile properties through a fluid dynamics two-phase model. The model was based on the melt-spinning method focusing on melt spinning, the environment of POLYFLOW, and the method of joint simulation, coupled with Nakamura crystallization kinetics, including the development of process collaborative parameters, stretch-induced crystallization, viscoelasticity, filament cooling, gravity term, inertia, and air resistance. Finally, for nylon 6 BHS and CN9987 resin spinning, the model successfully predicted the distribution changes in temperature, velocity, strain rate tensor, birefringence, and stress tensor along the axial and radial fibers and obtained the variation pattern of fibers' crystallinity along the entire spinning process under different stretching rates. Furthermore, we also explored the effects of spinning conditions, including inlet flow rate, winding speeds, and the extrusion temperature, on the fibers' crystallization process and obtained the influence rules of different spinning conditions on fiber crystallization. Knowing the paths of changes in mechanical performance can provide important guidance and optimization strategies for the future industrial preparation of high-performance fibers. [ABSTRACT FROM AUTHOR]

Hydrogen bonding is the prerequisite for polyamide fibers to have better stress–strain behavior. It affects the crystal structure of polyamide fibers, such as orientation and periodic arrangement. To illustrate the effect of intermolecular hydrogen bonding on fiber orientation structure and macroscopic mechanical properties, this work uses conventional polyamide resin doped with high molecular weight components to construct polymer compounds with discrete distribution characteristics. By analyzing the changes in intermolecular hydrogen bonds, melt rheological properties, non‐isothermal crystallization behaviors, the impact of hydrogen bonds on the crystal structure and orientation structure and thus on the fiber strength was clarified. The doping of high molecular weight components can make the compound form more hydrogen bonds and inhibit the relaxation of molecular chains through entanglement, thereby promoting melt non‐isothermal crystallization process and increasing complex viscosity η* and storage mode G'. 1D and 2D wide‐angle and small‐angle X‐ray scattering show that doping components reduce crystal size of α1(200) and α2(002, 202) planes from 4.19 to 3.47 nm and 5.88 to 4.96 nm, resulting in a denser long‐period structure. Through the strategy of this work, polyamide 6 fibers' tensile strength is effectively improved by18%, and the mechanical properties are significantly improved. Highlights: High‐strength polyamide compound fibers were prepared.Discretely distributed compounds are achieved.Discretely distributed molecular weight enabled hydrogen bonding regulation.Hydrogen bonding‐induced compound fiber crystal structure.Multiple external fields induced crystallization and orientation structures. [ABSTRACT FROM AUTHOR]

The influence of axial steric hindrance in α-diimine nickel catalysts on ethylene polymerization is paramount for enhancing the catalytic performance especially in terms of thermal stability and polymer molecular weights. In this study, a set of five nonsymmetrical 1,2-bis(arylimino)acenaphthene–nickel complexes, incorporating 2,6-bis(bis(4-fluorophenyl)methyl)-3,4,5-trimethoxyaniline and 2,4,6-trialkylaniline moieties, was prepared to tailor the catalytic attributes for ethylene polymerization. In-depth studies on the polymerization of ethylene, using two different cocatalysts and different reaction conditions, revealed exceptional catalytic activities for these precatalysts with activity levels as high as 20.3 × 106 g mol−1 h−1 at 30 °C and high molecular weights of the obtained polyethylene with adjustable branching degrees and distributions. Reactions at elevated temperatures validated the enhanced thermal stability of Ni-Me2 precatalysts, displaying a noteworthy activity of 1.4 × 106 g mol−1 h−1 at 100 °C. Polyethylene derived from more sterically hindered nickel complexes exhibited relatively higher molecular weights and branching degrees compared to less hindered analogues. This trend was consistent across mechanical and elastic properties, which ranged from 6.1 MPa to 10.6 MPa and 26% to 49%, respectively. Moreover, the manipulation of branching degree by increasing the reaction temperature led to an elastic recovery of up to 63%, indicating potential formation of thermoplastic polyethylene elastomers. [ABSTRACT FROM AUTHOR]

Poly(ethylene terephthalate) (PET), extensively employed in bottles, film, and fiber manufacture, has generated persistent environmental contamination due to its non‐degradable nature. The resolution of this issue requires the conversion of waste PET into valuable products, often achieved through depolymerization into monomers. However, the laborious purification procedures involved in the extraction of monomers pose challenges and constraints on the complete utilization of PET. Herein, a strategy is demonstrated for the polymer‐to‐polymer upcycling of waste PET into high‐value biodegradable and programmable materials named PEXT. This process involves reversible transesterifications dependent on ester bonds, wherein commercially available X‐monomers from aliphatic diacids and diols are introduced, utilizing existing industrial equipment for complete PET utilization. PEXT features a programmable molecular structure, delivering tailored mechanical, thermal, and biodegradation performance. Notably, PEXT exhibits superior mechanical performance, with a maximal elongation at break of 3419.2 % and a toughness of 270.79 MJ m−3. These characteristics make PEXT suitable for numerous applications, including shape‐memory materials, transparent films, and fracture‐resistant stretchable components. Significantly, PEXT allows closed‐loop recycling within specific biodegradable analogs by reprograming PET or X‐monomers. This strategy not only offers cost‐effective advantages in large‐scale upcycling of waste PET into advanced materials but also demonstrates its enormous prospect in environmental conservation. [ABSTRACT FROM AUTHOR]

Printing and dyeing wastewater, that is discharged after textile printing and dyeing processing, can cause irreversible damage to the aquatic ecosystem and harm the health of human beings. Till now, completely and readily removing dye molecules from industrial wastewater using a single catalyst rather than the combination of several materials remains a significant challenge. Herein, in situ preparation of carbon nanotube membranes (N‐CNTM and N‐TiO2‐CNTM) are reported that are doped using N with/without TiO2, respectively. These membranes can simultaneously function as an adsorber, a photo‐catalyst, and an electrocatalyst to efficiently remove dye pollutes from industrial waste water. Further researches reveal that the formation of p‐n type heterojunction inside of the N‐CNTM and N‐TiO2‐CNTM, can improve the hole separation and charge storage abilities, resulting in the efficient removal of dyes in the industrial waste water. This work provides a promising approach for the preparation of functionalized carbon nanotubes derived from waste biomass for the treatment of industrial water, reflecting the concept of treating waste with waste. [ABSTRACT FROM AUTHOR]

Protective clothing with fascinating flame‐retardant features is urgently needed to reduce the large amount of smoke and heat released from combustion during fire protection. In this study, polyphenylene sulfide (PPS) nanocomposite resin with efficient flame retardancy is obtained by mixing a low content of graphene and Fe2O3 via a twin screw extruder. Followed by, the PPS/G/Fe2O3 fibers are fabricated via melting spinning. The PPS/G/Fe2O3 nanocomposite resin with 0.3 wt% of graphene and 1.0 wt% of Fe2O3 performs the best during the flame retardant tests, giving a shorter self‐extinguishing time, lower peak heat release rate (22.3 kW/m2), total heat release (11.3 MJ/m2) and total smoke production (1.32 m2) than others. The pyrolysis analysis indicates that a large number of products with fused rings are formed in the residual char layer, which effectively inhibit the release of heat and smoke and thus improve the flame retardancy of PPS nanocomposite resin. In addition, the flame retardant textile weaved with PPS/G/Fe2O3 fibers gives a high‐limiting oxygen index (40.1%), zero after‐flame time, no droppings and small damaged length (114 mm in warp and 98 mm in weft direction) during the standard flame retardancy tests provided by a third‐party independent inspection organization. The fabrication of PPS fibers with effective and enhanced synergistic flame retardancy through melting spinning is facile and scalable, providing a promising strategy for advanced protective clothing. [ABSTRACT FROM AUTHOR]

The high value‐added application of lignin is of great significance for the effective utilization of biomass and environmental protection. In this work, TiO2‐loaded lignin‐derived carbon nanofibers (TiO2@LCNFs) are developed by the process of electrospinning, per‐oxidation, and carbonization. The effects of TiO2 content, carbonization temperature, initial RhB concentration, and solution pH value on the photocatalytic efficiency are systematically studied. Up to 86% photocatalytic efficiency and excellent cycling stability of the TiO2@LCNFs to rhodamine B under optimized conditions are achieved. The superior catalytic property of the TiO2@LCNFs can be attributed to the synergistic effect of the uniform distribution of TiO2 on the fiber surface and the good electrical conductivity of LCNFs. It is expected that this work will provide some guidance for the preparation of efficient photocatalytic materials, especially those based on biomass‐derived fiber materials. [ABSTRACT FROM AUTHOR]

Microencapsulated core–shell structures have proven to be an effective means for realizing high-enthalpy and shape-stabilized phase change materials (PCMs), but the low heat and shear resistance of the shell material seriously restrict their practical application in functional materials. Here, leak-free and shape-stabilized PCMs were fabricated by a strategy of confinement of phase change media via capillary adsorption on synthetic radial spherical silica (RSSiO2) scaffolds. The organic and inorganic components exchange the traditional core–shell positions, forming a new phase change composite with an inorganic material as the core layer. It not only endowed this composite with high-temperature regulation ability but also its enthalpy value was stabilized at 96.0 J g−1 after the heat treatment process. More importantly, its heat-resistant stability was significantly improved, reaching above 300–350 °C. This indicates that the core structure of inorganic RSSiO2 could not merely solve the inherent defects of conventional microcapsules but provides higher thermal stability as well, which is expected to be applied in high-temperature melt fiber spinning and electrical thermal management of devices. [ABSTRACT FROM AUTHOR]

Flexible aliphatic poly(lactic acid) is introduced into polyethylene terephthalate through copolymerization to prepare biodegradable copolyester, which aims to solve the non‐degradability of polyethylene terephthalate (PET) and realize the greening of raw materials. In this work, poly(ethylene terephthalate‐co‐lactic acid) random copolyesters (PETLAs) of lactic acid composition from 10 to 50% is synthesized via one‐pot method. The chemical structure and composition, thermal property, and crystallization property of prepared PETLAs resin are characterized. The results shows that the introduction of LA segment forms random copolyester, and the flexible LA segment results in slight decrease in the glass transition temperatures (Tg), melting point (Tm), and crystallinity (Xc) of the copolyesters. The thermal stability of PETLAs is better, and the initial decomposition temperature of PETLA‐10 can reach 394 °C. The PETLAs resin exhibits good processability, and PETLAs fibers are prepared by melt spinning. The strength of PETLA‐10 fiber can reach 260 MPa after drawing treatment, and the elongation at break can reach 130%. Taking advantage of their features, PETLAs as an innovative bio‐based polymer are expected to achieve ecofriendly applications in the fields of fiber, plastic, and film. [ABSTRACT FROM AUTHOR]

With their impressive properties such as high mechanical strength, high electrical and thermal conductivities, good corrosion and oxidation resistance, and excellent structural flexibility, carbon nanotube (CNT) fibers hold great promise for developing multifunctional fabrics. However, the preparation of such fabrics containing only CNT fibers through mature textile technologies in a fully automatic way remains a big challenge. Here, for the first time, we report the automatic fabrication of CNT fiber fabrics. This is achieved through knitting yarns composed of CNT fibers that are produced from a floating catalyst chemical vapor deposition based process using an automatic weft knitting machine. The resulting all-CNT fiber fabrics are flexible, light weight, mechanically strong, and electrically and thermally conductive. The promising applications of such multifunctional fabrics are demonstrated by using them as fast-responding electrothermal heaters and as high-performance fabric electrodes in flexible supercapacitors. We expect that this study will pave a new way for the use of CNT fibers in real-world applications. [ABSTRACT FROM AUTHOR]

Polyamide 6 (PA6) fiber has the advantages of high strength and good wear resistance. However, it is still challenging to effectively load inorganic antibacterial agents into polymer substrates without antimicrobial activity. In this work, graphene oxide is used as a carrier, which is modified with an aminosilane coupling agent (AEAPTMS) to enhance the compatibility and antimicrobial properties of the inorganic material, as well as to improve its thermal stability in a high‐temperature melting environment. Cuprous oxide‐loaded aminated grapheme (Cu2O‐GO‐NH2) is constructed by in situ growth method, and further PA6/Cu2O‐GO‐NH2 fibers are prepared by in situ polymerization. The composite fiber has excellent washing resistance. After 50 times of washing, its bactericidal rates against Bacillus subtilis and Escherichia coli are 98.85% and 99.99%, respectively. In addition, the enhanced compatibility of Cu2O‐GO‐NH2 with the PA6 matrix improves the orientation and crystallinity of the composite fibers. Compared with PA6/Cu2O‐GO fibers, the fracture strength of PA6/Cu2O‐GO‐NH2 fibers increases from 3.0 to 4.2 cN/dtex when the addition of Cu2O‐GO‐NH2 is 0.2 wt%. Chemical modification and in situ concepts help to improve the compatibility of inorganic antimicrobial agents with organic polymers, which can be applied to the development of medical textiles. [ABSTRACT FROM AUTHOR]

The approach of in situ polymerization modification has proven to be an effective route for introducing functions for polyester materials. In this work, Cu2O@ZrP nanosheets with excellent dispersity and high antibacterial activity were integrated into in situ polymerized polyethylene terephthalate (PET) fibers, revealing an enhanced mechanical performance in comparison with the PET fibers fabricated directly via a traditional melt blending method. Additionally, such an in situ polymerized PET/Cu2O@ZrP fibers displayed highly enhanced mechanical properties; and great antibacterial activities against multi-types of bacterium, including S. aureus, E. coli and C. albicans. For the as-obtained two types of PET/Cu2O@ZrP fibers, we have detailed their molecular weight (detailed molecular weight) and dispersibility of nano-Cu2O@ZrP and fibers crystallinity was investigated by Gel chromatography (GPC), Scanning electron microscope (SEM), and X-ray diffractometer (XRD), respectively. The results showed that the aggregation of the nano-Cu2O@ZrP in the resultant PET matrix could be effectively prevented during its in situ polymerization process, hence we attribute its highly enhanced mechanical properties to its superior dispersion of nano-Cu2O@ZrP. [ABSTRACT FROM AUTHOR]

The fabrication of bio-based copolyester fiber with adjustable crystallization, orientation structure and mechanical property still remains a great challenge. In this study, a series of copolyester fibers based on terephthalic acid (PTA), ethylene glycol (EG) and l -Lactide (L-LA) were prepared via melt copolymerization and spinning. The resultant PLA- co -PET (PETLA) fibers exhibited tunable structure and property due to the synergistic effects of chemical structure and drawing process. The chemical structure of PETLA was confirmed by NMR, FTIR and XRD, which suggested that the random degree of copolymer increased with LA content and the viscosity decreased with the increase of LA content. The crystallization behavior, melting characteristic, thermal stability and rheological property were investigated by DSC, TGA and rheometer, the results indicated that all the PETLA exhibited the crystallization capacity, melting temperature and thermal stability were slightly affected by LA segment. The synergistic effects of LA segment and spinning process on PETLA structure and property were analyzed by WAXD and SAXS. The breaking strength of PETLA fibers dropped from 5.3 cN/dtex of PET to 2.8 cN/dtex of PET 85 LA 15 , which still met the requirements of most textile applications. Therefore, our work presented a feasible approach to prepare bio-based polyester fibers with tunable property. [ABSTRACT FROM AUTHOR]

Lignin remains the second abundant source of renewable carbon with an aromatic structure. However, most of the lignin is burnt directly for power generation, with an effective utilization rate of <2 %, making value addition on lignin an urgent requirement. From this perspective, preparation of lignin-based carbon fibers has been widely studied as an effective way to increase value addition on lignin. However, lignin species are diverse and complex in structure, and the pathway that enables changes in lignin structure during pretreatment, fiber formation, stabilization, and carbonization is still uncertain. In this review, we condense the common structural evolution route from the previous studies, which can serve as a guide towards engineered lignin carbon fibers with high performance properties. • The structure and classification of lignin are summarized. • The characteristics of different lignin extraction methods are summarized. • The characteristics of different lignin pretreatment processes are summarized. • The characteristics of different lignin fiber preparation methods are summarized. • The characteristics of different lignin fiber treatment processes are summarized. [ABSTRACT FROM AUTHOR]

• The effect of interface interaction on the conductivity was study in detail. • A "Cage Effect" phenomenon between the graphene and PVA matrix was proposed. • Such a proposed CE was combined with the classical theory to boost conductivity. • A superior conductivity (25 S m−1) at 6.25 wt% graphene was obtained. Conductive graphene/polymer nanocomposites have drawn particular attention owing to their great promising in various environmental and energy-related applications. A percolation theory based on variation of conductive filler fraction has been demonstrated as the central guide for their fabrications. However, it typically fails in some special cases since the assumption has ignored the effect of interfacial interaction between the conductive nanofillers and the material matrix. Herein, we employ a graphene/poly(vinyl alcohol) model to study the effect of interfacial interaction on their electrical conductivity by using two types of graphene with different oxygen content. We further demonstrate "cage effect" as a critical role on their conductivities, which arise from the interfacial hydrogen bonding interaction between the graphene nanofiller and PVA matrix. A "cage effect" modified percolation theory gave an excellent match with the experimental data. Notably, such "cage effect" can be effective alleviated by applying a hot drawing treatment, thus achieving a higher electrical conductivity. As such, we successfully fabricate a graphene/PVA composite with a superior electrical conductivity up to 25 S m−1 at a 6.25 wt% graphene. Its excellent electronic stability after multiple bending operations was also verified in a laboratory prototype device to confirm its suitability for flexible electronics. [ABSTRACT FROM AUTHOR]

Quick-drying fabrics, renowned for their rapid sweat evaporation, have witnessed various applications in strenuous exercise. Profiled fiber textiles exhibit enhanced quick-drying performance, which is attributed to the excellent wicking effect within fibrous bundles, facilitating the rapid transport of sweat. However, the evaporation process is not solely influenced by macroscopic liquid transport but also by microscopic liquid spreading on the fibers where periodic liquid knots induced by spontaneous fluidic instability significantly reduce the evaporation area. Here, a cross-shaped profiled fiber with high off-circularity, featured as multiple concavities along the fibrous longitude-axis, which enables the formation of a homogeneous thin liquid film on a single fiber without any periodic liquid knots, is developed. The high off-circularity cross-sections help overcoming Plateau-Rayleigh instability by tuning the Laplace pressure difference, further facilitated by capillary flow along the concave surface. The homogeneous thin liquid film on a single fiber is responsible for maximizing the evaporation area, resulting in excellent overall evaporation capacity. Consequently, fabrics made from such fibers exhibit rapid evaporation behavior, with evaporation rates ≈50% higher than those of cylindrical fabrics. It is envisioned that profiled fibers may provide inspiration for the manipulating homogeneous liquid films for applications in fluid coatings and functional textiles., (© 2024 Wiley‐VCH GmbH.)