EFFECT OF POLYSTYRENE ON THE CRYSTALLIZATION OF POLY(3-HYDROXYBUTYRATE)
Lima Camila Ventura (1), Araujo Inaldo Cesar (1), Almeida Yêda Medeiros Bastos (1), Rabello Marcelo Silveira (2), Wellen Renate Maria Ramos (3)*, Canedo Eduardo Luis (3)
(1) Federal University of Pernambuco - Pernambuco - Recife - Brazil, (2) UFCG - Paraíba Campina Grande - Brazil, (3) ITEP - Pernambuco Recife - Brazil
Poly(3-hydroxybutyrate) (PHB) is a thermoplastic semi-crystalline polymer, completely biodegradable and biocompatible, obtained from renewable resources. Its high crystallinity prompted several studies on crystallization and melting behaviour and also on ways to increase the amorphous polymer fraction. This work is concerned with the Morphology and Nonisothermal Crystallization of poly(3-hydroxybutyrate) (PHB) and blends of PHB and polystyrene (PS) studied by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC), respectively. A two-phase structure composed by a PHB matrix and nearly spherical particles of PS can be clearly noticed in SEM images. The presence of small amounts (0.5% to 3%) of amorphous PS affects the crystallinity of PHB, the effect increasing with the cooling rate. The kinetics of nonisothermal crystallization was modeled according to Ozawa. Dependence of Ozawa parameters on temperature follow the same trend for PHB and PHB/PS blends; model parameters were found to be lower for the blends that for the neat PHB.