Gel Drawn Fibers of Poly(Vinyl Alcohol).
CORNELL UNIV ITHACA NY DEPT OF MATERIALS SCIENCE AND ENGINEERING
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Semi-crystalline gels of several samples of polyvinyl alcohol were made from solutions in which the polymer concentration varied from 2.0 to 15.0. Entanglement density in the material was in this way reduced from the melt entanglement density. When gels were partially dried and drawn isothermally the maximum draw ratio increased with drawing temperature up to 11-14 at 140-180 C. A melt cast film could be drawn to 6.8 times at 140 C. Drawn material had a crystallinity of 55-80, while that of isotropic material was 20-55. Gels of lower initial concentration lower entanglement density could be drawn to greater extensions at a given draw temperature and had better mechanical properties. Youngs modulus increased with draw ratio to values very close to those for polyethylene fibers drawn by the same amount. Youngs modulus was independent of drawing temperature or degree of crystallinity but on comparing drawn gels of the same draw ratio, crystallinity and crystalline orientation, those of lower entanglement density had higher Youngs modulus. Author