Spherulitic growth and crystallization kinetics in PHB/DGEBA blends

Abstract

A study of spherulitic growth in PHB and PHB/DGEBA (poly(3-hydroxybutyrate)/diglycidyl ether ofbisphenol A) blends with PHB/DGEBA weight ratios of 100/0, 90/10, 80/20, 70/30 and 60/40 crystallizedat temperatures in the range of 45?110◦C is carried out. The spherulitic growth rates at the crystallizationtemperatures are studied by optical microscopy. Differential scanning calorimetry is used to study thesame isothermal process to fit the results by means of the Avrami theory to determine the characteristicparameters of the process. The obtained characteristic parameters are compared to the spherulitic growthrates that are determined by optical microscopy. The observed differences are discussed considering theprocess of nucleation. An increase in the secondary crystallization process is observed with increasingcrystallization temperature and DGEBA content in the blend. Changes in the crystallization associatedwith an increase in the rigid amorphous fraction (RAF) mobility are discussed.