The effect of molecular weight on the crystallization kinetics and equilibrium melting temperature of poly(tetramethylene ether glycol)

Isothermal crystallization of poly(tetramethylene ether glycol) (PTMEG) with relatively low molecular weight (M-n=991, 2004 and 2864, respectively) was investigated by differential scanning calorimetry, and the equilibrium melting temperature (T-m(0)) determined using the Hoffman-Weeks analysis. The crystallization kinetics of PTMEG were characterized using an Avrami analysis. Mechanistic n values ranged from 2.2 to 2.9 for the primary crystallization process for three molecular weight grades, indicating heterogeneous nucleation of spherulites. Polarized light microscopy confirmed that PTMEG crystallized by the growth of spherulites from heterogeneous nuclei. The half-life for crystallization (t(1/2)) and the composite rate constant were found to be dependent on the degree of supercooling (Delta T) and the molecular weight. Copyright (C) 2006 John Wiley & Sons, Ltd.