聚氧化乙烯和聚丙烯酰胺在高速搅拌下的机械降解

本文分别研究了在高速搅拌下水溶液中聚氧化乙烯(PEO)和聚丙烯酰胺(PAM)的机械降解.在一定浓度范围内极限链长和降解速率常数随浓度变化而变化.在给定浓度下速率常数与搅拌时间有关.每一分子的断链次数对搅拌时间的依赖性可用如下方程描述:B_O=(P_O/P_∞-1)〔1-exp(-K_OP_∞t)exp(1/2K_1P_∞t~2)〕.据实验结果推测:在0.5%的水溶液中,无论PEO或PAM分子可能皆不形成缠结结构.由降解前后聚合物的GPC法分析可知,经降解的聚合物分子量分布变窄.

Mechanical Degradation by High-Speed Stirring of Poly(Ethylene Oxide)and Polyacrylamide

The mechanical degradation by high-speed stirring of poly (ethylene oxide) and polyacrylamide in aqueous solution were studied. The limiting chain length and the rate constant of degradation were shown to change with concentration, and the rate constant was shown to be related to stirring time at any given concentration. The dependence of the number of scission per molecule on stirring time can be expressed by the following equationAccording to the experimental result, it was inferred that molecules of neither polymer acquire the entanglement structure at a concentration of 0.5%.As shown by gel permeation chromatogram comparing the original and the degraded polymers, the molecular weight distribution of the latter became narrower.