Molecular weight dependence of primary nucleation rate of poly(ethylene succinate)

The molecular weight (MW) dependence of the primary nucleation rate (I) was studied for poly(ethylene succinate). The primary nucleation rate was measured in a wide range of temperatures. It has a bell shape with a maximum nucleation rate (I-max) that showed a remarkable MW dependence. I-max decreased first with MW to about 3000 and then increased. The MW of about 3000 was attributed to the transition from intermolecular nucleation to intramolecular nucleation. The MW dependence of I-max was expressed as I-max proportional to MWalpha. The value of a was negative unity for intermolecular nucleation and positive unity for intramolecular nucleation.