1993 Volume 50 Issue 12 Pages 929-934
An attempt was made to develop turtleshell-work-materials using silk protein as a substitute for natural turtleshell. For this purpose, thermal and mechanical properties of natural turtleshell and hotpressed fibroin were investigated using DSC, thermal mechanical analysis (TMA), bending test, etc. Wet turtleshell preheated and pressed had softening point at about 30°C, and softening proceeded rapidly above 80°C. The turtleshell had endothermic DSC peaks at about 40 and 70°C. The optimum conditions of hotpress for silk fibroin powder to make hotmelt boards were as follows: moisture content 27%, pressure 450kg/cm2, temp. 160°C, and hotpress time 1min. The board obtained under the conditions showed Vickers hardness, about 30 kgf/mm2, similar to that of turtleshell. However, the bending property under dry or wet-heat conditions and clarity were inferior to those of turtleshell. Such a defective characteristics of the board was attributed to the facts that this fibroin powder did not melt perfectly by hotpress, and the board has no multi-layer structure unlike turtleshell.
