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SynopsisFour 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 6N HC1 at 4OoC, whereas the other wild varieties of silk were hydrolyzed partially using 8N HC1 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 verified 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.

Unoriented (UPP) and biaxially oriented (BOPP) polypropylene films were treated under radio frequency plasma of air, nitrogen, oxygen, and ammonia. Surface modification of polypropylene films was investigated by using surface energy measurement and attenuated total reflection (ATR)-FTIR spectroscopy. Surface energy of air and nitrogen plasma-treated polypropylene film increased for shorter treatment time and then decreased and attained an equilibrium value. Such changes in surface energy were not observed for oxygen and ammonia plasma-treated polypropylene film, which increased to an equilibrium value. ATR-FTIR studies revealed characteristic differences in the absorption spectra for short-duration and long-duration treatments. From the relative intensity change in the C-H stretching vibration, the mechanism of surface chemical reaction could be inferred. Studies regarding the durability of surface modification due to plasma treatment were evaluated by investigating surface energy of samples aged for 2 months. Treated films subjected to peel strength measurement showed improvement in bondability for UPP and BOPP film by hydrophilic surface modification accompanied by surface crosslinking.

The present paper reports the effect of plasma treatments on the surface properties of textile fibers. In the present investigations mainly air plasma and dichlorodifluoromethane (DCFM) plasmas were used. Measurement of the contact angle, wicking properties, and dyeability of cotton fabrics subjected to various conditions of plasma treatments have been carried out. It was observed that while air plasma produced enhanced water wicking, DCFM plasma resulted in producing a highly water-repellent, hydrophobic surface. The contact angle increased dramatically for the DCFM plasma-treated fabrics up to 140°. It was also observed that plasma treatment has improved the dyeing behavior of cotton fabrics when reactive and natural dyes were used. On the other hand, the dyeability was found to have slightly decreased when direct dye was used.