Isothermal crystallization behavior of biodegradable poly (butylene succinate-co-terephthalate) (PBST) copolyesters at high undercoolings

Poly ( butylene succinate-co-terephthalate) (PBST) copolyesters were prepared by polycondensatioa The isothermal crystallization behavior of the as-prepared copolyesters was investigated by depolarized light intensity ( DLI ) at high undercoolings. According to Avrami equation, the exponent n, independent of the crystallization temperature, is at a range of 2.5 to 3. 4, which probably corresponds to the heterogeneous nucleation and a 3-dirnensional spherulitic growth. The maximum crystallization rate, very useful to polymer processing, was found at about 90°C based on the half-crystallization time t1/2analysis.