Journal of Materials Science, Vol.33, No.9, 2331-2338, 1998
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 high-modulus drawn poly(vinyl alcohol) (PVA) film could be obtained from aged gel sheet. In this paper, the effect of pressing temperature, at which the original PVA/dimethylsulphoxide/water gel was pressed into the gel sheet, on the tensile properties (modulus and strength) of the finally obtained drawn film is reported. The properties of the drawn films are discussed in relation to the structure of the undrawn films and the gel sheet, by birefringence and molecular orientation measurements, differential scanning calorimetry, and X-ray diffraction methods. As a result, the content of the low melting-temperature crystal component in the pressed gel is shown to be the most effective factor affecting the properties of the drawn film.