Rheological studies of the polymerization of elastomeric impression materials. II. viscosity measurements

As part of a detailed study of the curing of a range of dental elastomeric impression materials, a cone and plate rheometer was used to measure the variation in viscosity due to chain growth. The dependence of this behavior on the catalyst/base ratio, retarding and accelerating agents, and alternative initiators was studied and rationalized in terms of the polymerization chemistry investigated previously. Limited success was achieved with the quantitative interpretation of this data in terms of the polymerization kinetics. Of clinical relevance, only the viscosity behavior of the imine-terminated polyether and one of the thiol-terminated polysulfides approached that of an ideal impression material.