STRUCTURES OF POLY(VINYL ALCOHOL) POLY(STYRENE SULFONIC-ACID) SODIUM-SALT BLEND HYDROGELS AND CONTRACTION BY ABSORPTION OF WATER INTO DRIEDBLEND HYDROGELS IN THE DRAWN STATE

Hydrogels, which have high modulus even with relatively high water con tent, were prepared by dissolving poly(vinyl alcohol) (PVA) with poly( styrene sulfonic acid) sodium salt (NaPSS) in an autoclave at elevated temperature and pressure, then dehydrating and swelling in water. The high modulus was mainly due to crosslinked structures formed by inter polymer complex not made of PVA crystallites. The contraction of blend gels, which are drawn and dried in the drawn state, is caused by cont raction of oriented amorphous chains with absorption of water. The ori ented amorphous chains are mainly fixed by the crosslink formed by the interpolymer complex not the PVA crystallites.