关键词: 聚（N-乙烯基吡咯烷酮-co-甲基丙烯酸）, 烫发, 漂发, 抗拉伸, 梳理性

Abstract:

The repairing effect of poly （N-vinylpyrrolidone-co-methacrylic acid） on permed or bleached damaged hair was studied. The combing and tensile strength of permed and bleached hair before and after treatment with the copolymer solution were tested, and the effects of the mass fraction of copolymer solution and immerseing time on the combing and tensile strength for permed or bleached damaged hair were investigated. The repair mechanism of permed or bleached damaged hair was also explored. The results show that when the immersing time is 3 hours, the tensile strength of the permed hair increases with the mass fraction of the copolymer solution within 0%-0.3%, but no obvious change is observed when the mass fraction is over 0.3%. Therefore, the optimal mass fraction of the copolymer solution for repairing the permed hair is 0.3%. Similarly, the optimal mass fraction of the copolymer solution for repairing the bleached hair is 0.5%. Furthermore, the effects of immersing time on the tensile strength of the damaged hair fibers were compared between the permed and bleached hair before and after treatment with the copolymer solution. Coincidentally, the optimal immersion time for permed or bleached damaged hair is both 2 hours. The tensile strength of the permed and bleached hair soaked in 0.3% and 0.5% copolymer solutions for 2 hours increases by 15.55% and 18.12%, respectively, compared to untreated hair. Through infrared spectroscopy analysis, it is found that the amide II band in hair fibers shifted to the blue after repair, with the wave number shift of 11.12 and 11.09 cm^-1, which confirm the formation of hydrogen bonds in the hair samples. Additionally, the urea hydrogen bond disruption experiment demonstrates that urea does not disrupt the hydrogen bonds in untreated hair fibers, but prevents the formation of new hydrogen bonds in damaged hair fibers. It further validates that the improvement of the tensile strength of the copolymer treated damaged hair fibers is mainly due to the formation of hydrogen bonds. After treatment with the copolymer, the dry and wet combing friction decrease by 30.73% and 28.55% for the permed hair, and decrease by 28.55% and 24.83% for the bleached hairs, respectively. The scanning electron microscope shows that the copolymer can flatten the cuticle and fill the space between the raised cuticles.

Key words: poly （N-vinylpyrrolidone-co-methacrylic acid）, permed hair, bleached hair, tensile strength, combing