WATER-ABSORPTION AND STATES OF WATER IN SEMICRYSTALLINE POLY(VINYL ALCOHOL) FILMS

Thermal analysis of semicrystalline poly(vinyl alcohol) reveals the ex istence of up to three energetically distinct states of water within t he polymer structure. Wide angle X-ray studies indicate that diffusion of water into semicrystalline samples of the polymer gradually destro ys the crystalline regions of the polymer, although water is found to not inhabit intact crystallites. The nonfreezing water is responsible for the destruction of crystalline regions by a mechanism of disruptio n of intermolecular hydrogen bonds in the interface region between the crystalline and swollen amorphous regions. Water does not inhabit the polymer in clusters as freezable water until most of the inter and in tra molecular hydrogen bonding has been disrupted by the nonfreezing w ater. Copyright (C) 1996 Elsevier Science Ltd.