Abstract
The crystallization kinetics of poly(3-hydroxybutyrate) (PHB), PHB/NH
4
Cl composites, PHB/ethylene-vinyl acetate (EVA 80) blends and PHB/EVA 80/1 mass% NH
4
Cl blends were studied under non-isothermal conditions. The modified Avrami equation and the MO approach were found to successfully describe the non-isothermal crystallization process. It was found that the inverse half time of crystallization and the values of Avrami rate constant,
K
, of PHB increased with decreasing EVA 80 content, increasing cooling rate and the addition of NH
4
Cl. Moreover, the crystallization mechanism remains unchanged in spite of the EVA 80 content and the presence of NH
4
Cl. Furthermore, the effective energy barrier of the non-isothermal crystallization process,
E
X(t)
, was evaluated with the isoconversional methods of Friedman. The
E
X(t)
values of PHB/NH4Cl composites are much lower than those of pure PHB. Moreover,
E
X(t)
values of PHB in PHB/EVA 80/1 mass% NH
4
Cl increase with increasing EVA content. A large number of small PHB spherulites were observed by polarized optical microscopy in the presence of NH
4
Cl.