Non‐monotonic molecular weight dependence of crystallization rates of linear and cyclic poly(epsilon‐caprolactone)s in a wide temperature range

Abstract

Abstract By using a commercial fast‐scan chip‐calorimeter, the effect of molecular weight on the isothermal crystallization rates of linear and cyclic poly(epsilon‐caprolactone) samples (L‐ PCLs and C‐ PCLs ) is investigated. The results confirm the non‐monotonic molecular weight dependence of the crystallization rates of both L‐ PCLs and C‐ PCLs over a wide temperature range, previously observed only in the high temperature range, in which the medium molecular weight PCLs exhibit the highest crystallization rate. Chain‐end effects of L‐ PCL with medium molecular weights induce faster crystallization rates in specific low temperature regions, in comparison to that for counterpart C‐ PCL . This phenomenon no longer exists in high molecular weight samples because of ‘diluted’ chain‐end effects in long chain samples. © 2016 Society of Chemical Industry