在应力作用下聚氯乙烯降解的研究

A STUDY ON MBCHANOCHEMICAL DEGRADATION OF FOLYVINYL CHLORIDE

本文研究了聚氯乙烯(PVC)在振磨作用下的力化学降解及力化学降解对PVC力学性能的影响。结果表明,PVC的分子量随振磨时间的增加而降低,力化学降解动力学服从方程式(1/P_t—1/P_(in))=Kt+A(P_t:为振磨时间t时的聚合度,P_(in)为初始聚合度)。初始分子量高的PVC在降解的初始阶段(0～15h)有规断链为主;初始分子量较低的PVC在降解的初级阶段(0～20h)以无规断链为主。经适当降解的PVC的屈服强度和断裂强度均高于相应未降解PVC的强度。

The mechanochemical degradation kinetics and mechanism of PVC during vibromilling and the mechanical property of degraded PVC were studied. The results show that the molecular weight of PVC decreases with vibromilling time. The mechanochemical degradation kinetics of PVC obeys the equation:(1/P1-1/Pin)-Kt + A(Pt;the degree of polymerization at vibromilling time t ;Pin;the initial degree of polymerization). For higher molecular weight PVC,the chain scission takes place non-randomly at the initial stage of vibromilling degradation(0-15h). For lower molecular weight PVC, the chain is repaired mainly at random. The yield strength and the strength at break of the slightly degraded PVC are higher than those of undegraded PVC.