DEVELOPMENT OF TURTLESHELL-WORK-MATERIALS USING SILK PROTEIN - THERMAL AND MECHANICAL-PROPERTIES OF TURTLESHELL AND HOTPRESSED FIBROIN

An attempt was made to develop turtleshell-work-materials using silk p rotein as a substitute for natural turtleshell. For this purpose, ther mal and mechanical properties of natural turtleshell and hotpressed fi broin were investigated using DSC, thermal mechanical analysis (TMA), bending test, etc. Wet turtleshell preheated and pressed had softening point at about 30 degrees C, and softening proceeded rapidly above 80 degrees C. The turtleshell had endothermic DSC peaks at about 40 and 70 degrees C. The optimum conditions of hotpress for silk fibroin powd er to make hotmelt boards were as follows: moisture content 27%, press ure 450 kg/cm(2), temp. 160 degrees C, and hotpress time 1 min. The bo ard obtained under the conditions showed Vickers hardness, about 30 kg f/mm(2), similar to that of turtleshell. However, the bending property under dry or wet-heat conditions and clarity were inferior to those o f turtleshell. Such a defective characteristics of the board was attri buted to the facts that this fibroin powder did not melt perfectly by hotpress, and the board has no multi-layer structure unlike turtleshel l.