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M.-L. Cheng, and Y.-M. Sun

 Department of Chemical Engineering and Material Science, Yuan Ze University, Chung Li 320, Taiwan, China

Keywords: Crystallization, morphology, DSC, FTIR and POM

The crystallization and morphology of a series of partial crystalline poly(3-hydroxybutyrate) (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) were investigated by using DSC, FTIR, and POM techniques. In the DSC analysis, the melting behaviour was characterized during thermal heating processes. The primary melting peak in the first run became two overlapped peaks in a second run. When hydroxyvalerate (HV) content of PHBV increased, the separation of the primary melting peak became more distinct. Similar results were observed in the FTIR study. The absorbance peak for the crystalline functional group in the second heating run disappeared at lower temperature than that in the first heating run. The morphology of crystalline phase transformation of PHAs during a temperature changing process was    observed by POM. The observation confirmed that there were morphology differences in the course of the first and second heating process.