[Changes of ciscoelastic behaviour during curing of polyether rubber impression material].

To obtain a precise impression, it is indispensable to understand changes of physical property of the material used, during curing. The authors measured the viscosity and the storage modulus of polyether rubber which was recently introduced as a commercial impression material and tried to make clear the curing mechanism of the material. The less the amount of catalyst added to the base material, the more approximative is the behaviour to the first-order reaction. But according as the amount of catalyst increases the behaviour becomes not to be regarded as the first-order reaction, i.e., it is surmised that the curing reaction becomes so complicated. The more the amount of catalyst and the higher the temperature after mixing, the shorter is the setting time. The curing reaction of polyether rubber impression material is supposed to be completed in about 3 hours after mixing. Polyether rubber impression material showed the highest storage modulus among the three rubber impression materials not used, namely, polyether, polysulfide and silicone rubber. The values of this highest modulus of polyether rubber were about 2.4approximately2.8 times of those of polysulfide and silicone rubber impression material in 3 hours after mixing.