论文部分内容阅读
在前一报告中用混合級分法研究了多分散性对聚甲基丙烯酸甲酯在丙酮中第二維利系数的影响,且指出用渗透压法得到的A_2和用光散射法得到的A′_2,各分散性的影响是不同的。本工作用重复分級法来观察A_2值的变化。两个溶液聚合的聚甲基丙烯酸甲酯試样A和B,在丙酮-水体系中25°时进行逐步沉淀分級,取試样A的P 2/4級分,試样B的P 1/5,P 4/5級分,除留出一部分作渗透压測定外,进行重分級,所得級分中选取几个进行渗透压測定和第三次分級,再取其中几个級分作渗透压测定,測定方法同前文。測定的級分和結果如下表: 在表中級分标記下的两个数字,前者表示分子量
In the previous report, the effect of polydispersity on the second Villi coefficient of polymethylmethacrylate in acetone was investigated by the mixed fraction method, and the A 2 obtained by the osmotic pressure and the A ’_2, the impact of the dispersion is different. This work repeated grading method to observe changes in A_2 values. Two solution polymerized polymethylmethacrylate samples A and B were subjected to a stepwise precipitation classification at 25 ° in an acetone-water system, a P 2/4 fraction of sample A, a P 1 / 5, P 4/5 points, in addition to leaving part of the determination of osmotic pressure, the re-grading, the selected fraction selected for the osmotic pressure measurement and the third classification, and then take some of them for the osmotic pressure Determination, determination method with the previous. The determined fractions and the results are shown in the following table: Two numbers under the fractional marker in the table, the former representing the molecular weight