IMPROVEMENT OF HOT-WATER RESISTANCE OF POLY(VINYL ALCOHOL) HYDROGEL BY ACETALIZATION AND IRRADIATION TECHNIQUES

In order to improve the heat stability of poly(vinyl alcohol) (PVA) hy drogel, acetalized PVA was irradiated with electron beam irradiation. The acetalization was strongly affected by PVA water content. There is an optimum water content of 20-30% for acetalization of PVA. The PVA gave maximum tensile strength at a dose of 100 kGy before or after ace talization. The PVA hydrogel maintained tensile strength of 10 MPa, ev en after 90 min boiling (98 degrees C) in water or autoclave steriliza tion (121 degrees C). It was confirmed that irradiation after, or befo re, acetalization is effective for enhancing heat resistance of a PVA hydrogel. The hydrogel is transparent, soft, has high tensile strength , and high hot water resistance. (C) 1995 John Wiley and Sons, Inc.