KINETICS AND RHEOLOGICAL CHANGES OF THERMOSET POLYMERS IN REACTIVE PROCESSING.

During the process, mold filling has to be finished before the system viscosity reaches too high. The process is then followed by a curing stage in which the material is reacted to a high enough mechanical strength before being ejected. A detailed understanding of rheological and kinetic changes before the gelation point (i. e. , pre-gel study) is essential in determining mold filling characteristics and the similar study after the gelation point (i. e. , post-gel study) is important in determining the demolding time, network structure and mechanical properties of the final product. In most cases, material used is not a pure resin but a compound with additives such as reinforcing fillers, solvent, and, sometimes, a second reactive resin (e. g. , interpenetrating polymer network (IPN)). These additives are added to modify the physical properties of molding compound, which, however, may also affect the kinetic and rheological characteristics of the compound. The goal of this work is to use chemorheological techniques to study the effect of various additives on the reactive processing of thermoset molding compounds. A polyurethane is used as the model resin. CaCO//3 (filler), nitrobenze (solvent), unsaturated polyester and styrene (second reactive resin) are used as additives.