Application of Continuous Kinetics to Polymer Degradation

Abstract

Degradation of polydisperse polymers is studied in the framework of continuous kinetics which is directly based on continuous distribution functions which depend on the molecular weight and the time. A firstorder formalism is presumed. A Schulz-Flory distribution (with time-dependent parameters) is assumed to be valid during the entire time of degradation. Thus, an essential simplification of the solution procedure of the continuous rate equation is achieved. As a proof of accuracy, the approximation solution and the exact solution are compared for the case of “random scission.” Furthermore, the developed method is shown to be suitable for describing the experimental data of dextran degradation caused by acid hydrolysis, by ultrasonic irradiation, and by enzymatic attack. The model parameters fitted to the experimental data allow the evaluation of the scission probability as a function of the molecular weight and of the location of the bond to be broken within the molecule.