The mechenical properties of poly(ethylene terephthalate) fiber can be controlled over a wide range by the drawing process. We employed a CO_2 laser to heat a running fier rapidly and uniformly, allowing the fiber to be instantaneously dranw to a high draw ratio. Using this drawing process, we obtained high-performance poly(ethylene terephthalate) fibers from commercial-grade polymer (V = 0.621 dl/g). These fibers had a tensile strength of 0.96 GPa, a Young's modulus of 19.2 GPa, a maximum elongation of 18%, and 1.2% boil-off shrinkage. A thermal mechanical analysis was performed for all drawn fibers, and it was found that the maximum shrinkage stress and the temperature of maximum shrinkage increased stepwise at draw ratios of between 5 and 6.
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