[Thermal and viscoelastic properties and problems on measurement methods of JIS for inlay waxes (author's transl)].

Abstract

The thermal and viscoelastic properties of commercial inlay waxes were investigated by measurements of JIS (Japanese Industrial Standard), differential thermal analysis, dilatometry and dynamic viscoelasticity. The crystal transition from orthorhombic to hexagonal caused by paraffin was observed in inlay waxes. The thermal expansion of waxes was influenced by crystal transition temperature. The cooling shrinkage of internal wax pattern is smaller in wax having larger expansion from 25 degrees C to 37 degrees C. The viscoelastic properties of inlay waxes shifted to low temperature region with decreasing in crystal transition temperature. The various properties of inlay waxes greatly changed at temperature of peak for loss tangent. There were some problems on measurement methods of JIS and the reexamination of thermal expansion and flow was suggested. Commercial inlay waxes, respectively, have various different properties, but from these results the qualities of waxes can not be determined so it's necessary to choose a suitable wax according to various conditions.