Abstract:

Objective This study aims to develop high-performance functional regenerated keratin-based composite fibers by incorporating MXene into keratin/polyamide 6 (PA6) blends, addressing the critical drawbacks of low utilization efficiency, poor mechanical properties, and single functionality of existing regenerated keratin materials. It further seeks high-value recycling of waste wool resources, responding to global demands for green sustainability and circular economy in the textile industry, where waste textiles are mostly landfilled or incinerated, causing resource waste and environmental pollution.

Method Wool keratin was extracted via the reduction pretreatment-formic acid method using tris(2-carboxyethyl)phosphine hydrochloride as the reducing agent (80 ℃, 2 h reduction; 60 ℃, 5 h dissolution in 90% formic acid). Laboratory-synthesized MXene was compounded with keratin/PA6 (5: 5 mass ratio) spinning solution through wet spinning (30% ZnSO₄ coagulation bath, 0.5% glutaraldehyde, 40 ℃ spinning temperature). Process parameters (MXene content: 0.1%-1.2%, temperature: 40-70 ℃, time: 1-4 h) were optimized, and materials were characterized by SEM, XPS, FT-IR, XRD, electronic single-fiber strength testing, and xenon lamp-induced photothermal evaluation.

Results The optimal compounding conditions were confirmed as MXene mass fraction 0.6%, temperature 60 ℃, and time 3 h, which balanced MXene dispersion and keratin structural integrity. Consistent with MXene's intrinsic photothermal property reported in literatures, the composite fiber exhibited exceptional photothermal conversion performance. Infrared thermal imaging showed a temperature rise of 42.3 ℃ after 5 min of 1 000 W xenon lamp irradiation, while the MXene-free control only increased by 20.3 ℃. This efficiency surpassed many photothermal biopolymer composites due to MXene's conductive network accelerating photon-to-heat conversion. Mechanical tests demonstrated a breakthrough compared to conventional regenerated keratin fibers. Literatures show that most have breaking strength below 20 cN, but composite fiber generated in this research reached 40.44 cN, with elongation at break of 12.65%. This well outperforms the pure keratin/PA6 fiber (15.36 cN, 21.18%) and aligns with the β-sheet reinforcement mechanism reported in keratin fiber studies. SEM observations revealed MXene eliminated surface grooves and reduced internal pores at 0.6% content, forming a compact structure. However, MXene content >0.6% caused agglomeration, as seen in similar MXene/polymer systems. XPS analysis detected 0.12% Ti element, confirming successful MXene incorporation, with the composite retaining keratin's characteristic C, N, O, S elements. FT-IR spectra showed no shifts in amide A (3 282 cm^-1) and amide I (1 640 cm^-1) peaks, verifying physical bonding which avoid chemical modification that impairs keratin's biocompatibility. XRD results indicated MXene induced a 37% increase in keratin's β-sheet diffraction peak (20°), enhancing crystallinity from 18.2% to 29.1%, which directly contributed to mechanical improvement. Compounding at above 70 ℃ led to keratin hydrolysis (observed via reduced amide peaks), while time longer than 3 h caused uneven MXene dispersion, both resulting in performance degradation.

Conclusion MXene effectively endows keratin/PA6 fibers with superior photothermal conversion while enhancing mechanical properties and structural uniformity through physical compounding, addressing key limitations of regenerated keratin materials highlighted in literatures. This study provides a feasible technical approach for high-value waste wool utilization, leveraging MXene's photothermal advantages and keratin/PA6 blend biocompatibility. The composite fibers hold broad applications in functional textiles (e.g., thermal management fabrics), biomass materials, and medical thermotherapy patches. The optimized process offers strong industrial potential, contributing to resource conservation and the textile industry's green transition.

Key words: functional regenerated keratin material, wool keratin, polyamide 6, MXene, wet spinning, composite fiber, photothermal conversion performance