Spherulitic growth and crystallization kinetics in PHB/DGEBA blends

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