尼龙66中的凝胶含量分析

将尼龙66溶解在甲酸溶液中通过微孔过滤分离出不溶的凝胶,从而测定尼龙66中的凝胶含量(G),即过滤法测定G;另外,将尼龙66溶于质量分数96%的硫酸溶液中,制成质量浓度为0.01~0.1g/mL的尼龙66硫酸溶液,使用紫外-可见分光光度计对尼龙66硫酸溶液在波长为290nm左右处进行紫外吸收光谱分析,研究了其吸光度与过滤法测得的G可能存在的对应关系。结果表明:通过选择合适的微孔滤膜可分离尼龙66中最小粒径为220nm的凝胶,采用过滤法测定同一批次的尼龙66的G,对27组G的测定结果,通过Shapiro-Wilk检验法得出G的分布为正态分布;在95%的置信区间,采用过滤法测得的G的5次结果的平均值的误差为35μg/g,过滤法能较准确测定出尼龙66中的G;过滤法测定尼龙66中的G与采用紫外吸收光谱法测得的吸光度成线性关系,其拟合线性方程的线性相关系数为0.97,采用紫外吸收光谱法用于检测尼龙66的G是切实可行的;经过一定热处理的尼龙66中的G可以通过紫外吸收光谱法测定。

Analysis of gel content in nylon 66

The gel content(G)in nylon 66 was determined by filtration method comprising dissolving nylon 66 in formic acid solution and separating the insoluble gel by microporous filtration.Nylon 66 sulfuric acid solution with the mass concentration of 0.01-0.1 g/mL was prepared by dissolving nylon 66 in 96%sulfuric acid solution by mass fraction.The ultraviolet absorption spectra of nylon 66 sulfuric acid solution at the wavelength about 290 nm were analyzed by using ultraviolet-visible spectrophotometer.The possible relationship between its absorbance and G measured by filtration method was studied.The results showed that the gel with the lowest particle size of 220 nm can be separated from nylon 66 by selecting the appropriate microporous membrane;the G of nylon 66 in the same batch was determined by filtration method and the distribution of G was normal by Shapiro-Wilk test of 27 groups of G;the average error of the five results of G measured by filtration method was 35μg/g in 95%confidence interval,which indicated that the filtration method can accurately determine G in nylon 66;there was a linear relationship between G in nylon 66 determined by filtration method and the absorbance measured by ultraviolet absorption spectrometry,and the linear correlation coefficient of fitting linear equation was 0.97,which proved it feasible to use ultraviolet absorption spectroscopy to detect G in nylon 66;and G in nylon 66 after a certain heat treatment can be determined by ultraviolet absorption spectrometry.