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SynopsisThe zone-drawing method has been applied to prepare ultra-high modulus polyvinyl alcohol fibers. First, the suitable temperature for zone-drawing was decided. In the first zone drawing, when drawing temperature was as high as near melting point, the highest draw ratio and modulus were obtained. The modulus was further increased by repeating zone drawing and heat treatment. In this study, the highest dynamic moduli were 115 GPa at room temperature and 42 GPa at 200°C. The fiber has a sharp melting peak that appeared at 246OC and a small peak at 260°C in the DSC curve.

The zone‐drawing (ZD) method was applied three times to the melt‐spun poly(L‐lactic acid) (PLLA) fibers of low molecular weight (Mv = 13,100) at different temperatures under various tensions. The mechanical properties and superstructure of the ZD fibers were investigated. The resulting ZD‐3 fiber had a draw ratio of 10.5, birefringence of 37.31 × 10−3, and crystallinity of 37%, while an orientation factor of crystallites remarkably increased to 0.985 by the ZD‐1. The Young's modulus and tensile strength of the ZD‐3 fiber respectively attained 9.1 GPa and 275 MPa, and the dynamic storage modulus was 10.4 GPa at room temperature. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 991–996, 1999