Simulation of degradation processes: Influence of degradation on molecular weight distribution: First approach. I. Random crosslinking and chain scission

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AbstractThe properties of polymers are changed by the influence of degradation processes. Easy to notice are changes in color caused by the formation of chemical groups absorbing the light spectrum in the visible region. The changes in color can, therefore, be determined and measured by sufficiently sensitive photometers, especially because the changes in the visible region are preceded very often by changes in the UV‐region.Mechanical properties, as well as rheological properties (and consequently the processa‐bility of polymers), depend on the relaxation spectrum which is sensitive to changes in the molecular weight distribution of the polymers.The molecular weight distribution is changed by the influence of degradation as a consequence of crosslinking, chain scission, and depolymerization.The questions concerning the influence of degradation processes on the molecular weight distribution of the polymers have hitherto been given less attention than the question regarding the color changes, although these, too, are of considerable importance.The determination of the gel content and the limit viscosity numbers which are usually employed as a measure for successive degradation processes is less suitable than the determination of the molecular weight distribution, as it gives less information especially in the initial stage of degradation and its interpretation is often difficult.The aim of this paper is to create a simple model suitable for a computer which would make possible the simulation of the influence of degradation processes on the molecular weight distribution. The results thus obtained should serve as a basic material for a detailed study of these questions.