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Enhancing the drawability of a polyester by copolymerization with a second type of crystallizable block



A polyester-amide segmented block copolymer with short monodisperse amide segments was synthesized along with its neat polyester counterpart. The copolymer, containing 10 wt % amide, displayed a Tg and Tm for the polyester phase as well as a high Tm corresponding to the polyamide. The high-melting amide segments enhanced the dimensional stability of the copolymer and also considerably increased the crystallization rate of the polyester segments. As compared to the neat polyester, the polyester-amide block copolymer could be drawn at higher temperatures and to higher draw ratios. The maximum draw ratio for this copolymer was obtained just a few degrees below the melting temperature of the polyester segments, and as a result of these higher draw ratios, the fracture stresses were higher. In conclusion, a short monodisperse amide segment in a polyester-amide block copolymer increased the crystallization rate of the polyester, enhanced the dimensional stability, allowed a higher maximum draw ratio, and raised the fracture strength. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011