Crystallization behaviour of poly(vinylidene fluoride)

Crystallization of poly(vinylidene fluoride) is investigated by calorimetry and wide-angle X-ray scattering. It is shown that in addition to alpha and gamma crystallization at high temperatures, alpha crystallization occurs at low temperatures. It is probable that low temperature alpha crystallization occurs from the segments with high concentration of head-to-head defects which are unable to crystallize at high temperatures. The Hoffman-Weeks plot of alpha crystallites formed at high temperatures is affected by additional low temperature alpha crystallization. The change in slope of a Hoffman-Weeks plot for alpha crystallites, reported in several papers, occurs only in the structure additionally crystallized during cooling to room temperature. The equilibrium melting temperature of the alpha and gamma form is determined from the Hoffman-Weeks plot. (C) 1999 Elsevier Science Ltd. All rights reserved.