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