Crystallinity in silk fibers: Partial acid hydrolysis and related studies

Abstract Four Indian varieties of silk viz., Mulberry, Tasar, Eri, and Muga, have been investigated by x‐ray diffraction and infrared spectroscopy. The hydrolysis for Mulberry was carried out using 6 N HCI at 40°C, whereas the other wild varieties of silk were hydrolyzed partially using 8 N HCI at 40°C. The x‐ray order factor, IR crystallinity index, and crystallite size have been determined for control, 48‐hr hydrolysates, and (48 + 48)‐hr hydrolysates. The lateral order improvement need not be associated with selective dissolution of amorphous region. This was further varified by short duration hydrolysis. A sort of recrystallization process could be attributed to order improvement. The results are discussed to understand the fine structure of the crystalline region of the fibroin.