抄録
Recently, acrilic resin materials have been developed as pattern materials for an inlay, crown, bridge and a metal frame of removable partial denture.
These materials possess several good properties (such as a low coefficient of thermal expansion (81×10-6) and a less tendency for stress relaxiation which may result in dimensional changes compared with wax.
These properties must be fully understood if the material is to be used satisfactory. In this investigation, the particle size, the variation of viscosity after mixing and the temperature changes of monomer-polymer mixture of commercial resins (Unifast, Duralay, Palavit G) were examined respectively.
The results obtained as follows:
1) The peak in particle size distribution of materials used was 40 to 60μ. It was observed that all materials tested possess a great number of granulated resin in addition to sphelical resin.
2) The resin, which has particle size in the range 0 to 20μ, in order, was: Unifast, Duralay and Palavit G.
3) The variation of viscosity with time after mixing was marked Unifast, Duralay and Palavit G, in order.
