Degradation of polycarbonates. III. Viscometric study of thermally‐induced chain scission

Measurements of the intrinsic viscosity of a polycarbonate degraded thermally in vacuum show that the polymer undergoes random chain scission according to the equation The viscosity results obtained in methylene chloride yield a value of α, the exponent of the Kuhn‐Houwink equation in agreement with the published value (0.83) obtained by osmometry. Analysis of the molecular weight changes occurring during degradation at various temperatures shows that the chain scission process obeys first order kinetics and can be expressed by the rate equation k = 4.8·10 7 ·e −39,500/RT .