Modeling Strategy for Networks with Both Stepwise and Chainwise Mechanisms: Amine-Epoxy Chemistry with Etherification

摘要

A comparison between the entirely statistical and the combined kinetic and statistical models for amine-epoxy networks, both studied previously in the literature, is made. The chemistry studied involves the generation of a secondary site, which reacts in the network through chainwise addition, rather than the stepwise addition mode of the primary reaction. It is shown that the combined model (Bokare and Gandhi, 1980) is exact and the random model (Bidstrup, 1986; Riccardi and Williams, 1986; and Tsou and Peppas, 1988) is approximate. The assumptions underlying the two models are delineated. It is shown that under certain circumstances the predictions of the two models can differ by several hundred percent. Further, the combined model is extended to predict the postgel properties of the network. Keywords: Crosslinking (Chemistry): Ethers. (aw)