Structure and processability of iodinated poly(vinyl alcohol). II. Drawability of iodinated films

Abstract

The drawability of poly(vinyl alcohol) (PVA) films iodinated with 0.1, 0.3, 0.5, 1.0, and 2.0 mol/L I2/KI aqueous solutions was examined with a tensile tester and a hand-operated drawer at 30–150°C. The structure of the films drawn to a maximum draw ratio (MDR) and deiodinated was determined by X-ray diffractometry, differential scanning calorimetry, and birefringence. Generally, the improvement of the drawability for the PVA film via iodination was ascertained by the increased breaking strain and decreased yield stress on the stress–strain curves when increasing the I2/KI concentration of the aqueous solutions used in the iodination. The MDR was generally increased with the concentration of I2/KI and the draw temperature. However, it diminished instead when close to the highest temperature and concentration of I2/KI, which was likely due to molecular degradation by the action of iodine as an oxidizer. The variation of the structure of the films drawn and deiodinated seems to be dependent mainly upon the MDR rather than the concentration of I2/KI. The greater the MDR was, the higher the degree of crystallinity, birefringence, and initial modulus were but the lower the melting temperature. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95:1209–1214, 2005