高密度聚乙烯熔体在超声辐照下的机械化学降解动力学及其机理

Mechanochemical degradation kinetics of high-density polyethylene melt and its mechanism in the presence of ultrasonic irradiation.

作者信息

Li Yuntao, Li Jiang, Guo Shaoyun, Li Huilin

机构信息

The State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China.

出版信息

Ultrason Sonochem. 2005 Feb;12(3):183-9. doi: 10.1016/j.ultsonch.2003.10.011.

DOI:10.1016/j.ultsonch.2003.10.011

PMID:15491880

Abstract

In this paper, the effect of ultrasonic intensity on the degradation of high-density polyethylene (HDPE) melt, degradation mechanism, ultrasonic degradation kinetics of HDPE melt as well as the development of molecular weight distribution of HDPE melt during ultrasonic degradation were studied. In the initial stage, the ultrasonic degradation of HDPE melt shows a random scission process, and the molecular weight distribution broadens. After that, the ultrasonic degradation of HDPE melt shows a nonrandom scission process, and the molecular weight distribution of HDPE melt narrows with ultrasonic irradiation time. The average molecular weight of HDPE decreases with the increase of ultrasonic intensity and increases and trends forward that of undegraded HDPE with the increase of distance from ultrasonic probe tip, indicating that attenuation of ultrasonic intensity in HDPE melt is very quick. Ultrasonic degradation kinetics of HDPE melt obeys the equation: Mt=M(infinity) + Ae(-kt). The theoretic calculation by this equation accords well with the experimental results. The plausible ultrasonic degradation mechanism of polymer melt based on molecular relaxation was also proposed in this paper.

摘要

本文研究了超声强度对高密度聚乙烯（HDPE）熔体降解的影响、降解机理、HDPE熔体的超声降解动力学以及超声降解过程中HDPE熔体分子量分布的变化。在初始阶段，HDPE熔体的超声降解呈现无规断链过程，分子量分布变宽。之后，HDPE熔体的超声降解呈现非无规断链过程，HDPE熔体的分子量分布随超声辐照时间变窄。HDPE的平均分子量随超声强度的增加而降低，随距超声探头尖端距离的增加而增大并趋向于未降解HDPE的平均分子量，这表明超声强度在HDPE熔体中的衰减非常快。HDPE熔体的超声降解动力学符合方程：Mt = M(∞) + Ae(-kt)。由该方程进行的理论计算与实验结果吻合良好。本文还基于分子松弛提出了聚合物熔体可能的超声降解机理。