A theory of network formation in irradiated polyesters

Abstract

Many polyester systems may be converted to insoluble materials when subjected to high-energy radiation. The radiation doses required are far lower than would be predicted on the theory of random cross-linking, indicating that the process involved is a chain reaction, acting through double bonds. Present theories of network formation are not applicable to such reactions. A mathematical analysis is given, applicable to a chain reaction the extent of which is limited by an inhibiting factor. The gel point and the solubility are deduced as functions of the cross-linking index and the inhibitor activity, for molecules of various sizes and distributions. These results are then related to the radiation dose. The model proposed may be applicable to chain reacting systems in which the reaction is not terminated by the interaction of two growing chains.