High-strength and high-modulus poly(vinyl alcohol) by the gel-ageing method - Part II - The effect of the gel pressing temperature

It was reported in our previous paper that a relatively high-strength and h igh-modulus drawn poly(vinyl alcohol) (PVA) film could be obtained from age d gel sheet. In this paper, the effect of pressing temperature, at which th e original PVA/dimethylsulphoxide/water gel was pressed into the gel sheet, on the tensile properties (modulus and strength) of the finally obtained d rawn film is reported. The properties of the drawn films are discussed in r elation to the structure of the undrawn films and the gel sheet, by birefri ngence and molecular orientation measurements, differential scanning calori metry, and X-ray diffraction methods. As a result, the content of the low m elting-temperature crystal component in the pressed gel is shown to be the most effective factor affecting the properties of the drawn film. (C) 1998 Chapman & Hall.