关键词: 羟胺, 菠萝蛋白酶, 木瓜蛋白酶, 复合酶, 生物酶, 羊毛, 定向摩擦效应, 抗起毛起球性能

Abstract:

Objective In order to address the persistent challenge of fuzzing and pilling in wool knitted fabrics, this study aimed to develop an eco-friendly surface modification technology by integrating hydroxylamine pretreatment with bromelain-papain composite enzymatic hydrolysis. The research focused on systematically improving anti-pilling performance of wool fiber while maintaining its inherent comfort, mechanical properties, and thermal insulation, addressing the limitations of conventional chemical treatments that cause excessive fiber damage and environmental pollution.

Method This study employed hydroxylamine pretreatment in combination with bromelain-papain composite enzymatic hydrolysis to effectively cleave thioester and amide bonds on the wool surface, thereby achieving efficient removal of wool scales and enhancing anti-pilling properties. Fourier transform infrared spectroscopy(FT-IR), X-ray diffraction(XRD), X-ray photoelectron spectro scopy (XPS), thermogravimetric analysis(TGA), differentrial scanning calorimetry(DSC), and scanning electron microscopy(SEM) characterization techniques were employed to analyze the microstructural and chemical compositional changes in wool before and after treatment. Furthermore, the influence of hydroxylamine concentration, pretreatment temperature, and time, as well as the concentration, treatment temperature, time, and pH value of both individual and synergistic protease treatments on the directional friction effect of wool fibers, fabric anti-pilling performance, mechanical properties, and wearing comfort, ultimately identifying optimal process parameters were systematically investigated.

Results The modified wool demonstrated multi-dimensional enhancements validated by analytical techniques. XRD revealed a 35.6% decline in crystallinity (23.6% to 15.2%), which was corroborated by weakened amide band absorption in infrared spectroscopy, indicating disrupted keratin structures. XPS revealed a 9.6% reduction in surface carbon content (71.8% to 64.9%) and a 66.7% increase in nitrogen content (3.9% to 6.5%), reflecting chemical composition changes induced by hydroxylamine and enzymatic treatments. The slight decrease in thermal stability by TGA and DSC indirectly confirms that the wool cuticle layer has been hydrolyzed. At the same time, SEM confirmed the complete removal of the scale. Hydroxylamine pretreatment (pH=7.5, 5%, 60℃, 60 min) effectively removed lipid layers, increasing surface energy and hydrophilicity for optimal enzymatic conditions. Bromelain-papain synergistic treatment (ratio of 1∶1, 50 ℃, 50 min, pH=7.0) achieved superior scale degradation compared to single protease, elevating pilling grade to 5 (0.5 higher than single-protease systems). Functional tests revealed a 56.9% reduction in directional friction effect (12.3% to 5.3%), achieving anti-pilling grade of 5. Comfort properties were enhanced through a 23.3% improvement in moisture permeability (116.3 to 143.4 g/(m²·d)), while maintaining air permeability and top-breaking strength. The modified fabric exhibited accelerated dyeing rates and maintained thermal insulation while demonstrating exceptional wash durability, with only a 0.5-grade reduction in pilling after 10 wash cycles.

Conclusion Hydroxylamine pretreatment (pH=7.5, 5%, 60 ℃, 60 min) effectively removes the lipid layer of the wool fiber, significantly enhancing hydrophilicity and wetting performance while balancing between mechanical properties for optimal enzymatic treatment. Synergistic bromelain and papain catalysis (protease ratio of 1∶1, 50 ℃, 50 min, and pH=7.0) fully degrades scale layers, achieving pilling grade of 5, 0.5 grades better than single-protease treatments. The modified fabric demonstrated accelerated dye uptake, 23.3% higher moisture permeability, and excellent wash durability (0.5-grade reduction after 10 wash cycles), while maintaining air permeability, thermal insulation, and mechanical properties. These results collectively indicate that combined chemical-enzymatic modifications enhance the surface morphology, thermal stability, comfort, and durability of wool fabrics by controlled scale degradation and chemical optimization.

Key words: hydroxylamine, bromelain, papain, composite protease, biological protease, wool, directional friction effect, anti-pilling performance