The analyses of the melting-recrystallization and the thermo degradation behaviors of Poly-3-hydroxybutyrate

• Main Authors: Hung-Fu, Huang, 黃宏富
• Other Authors: Shinn-Gwo, Hong
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/70470969616890460690

碩士 === 元智大學 === 化學工程學系 === 93 === The thermo-degradation and the formation of multiple-endothermic behaviors of the poly-3-hydroxybutyrate (PHB) during heating are studied with differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), thermo gravimetric analysis (TGA), and gel permeation chromatography (GPC). DSC results indicate that the crystallization rate and the multiple-endothermic behavior are affected by the treating temperature and the duration of heat treatment. The degree of degradation of PHB increases with the treating temperature and time. In addition, the atmosphere used in TGA analyses can affect the degradation process and shift the temperature of the maximal weight loss rate to a higher temperature by changing the nitrogen to air environment. The formation of unsaturated C=C and acid groups accompanied by the decrease of hydrocarbon groups, and the decrease of molecular weight of PHB during thermo exposure are confirmed by FTIR and GPC analyses, respectively. It is obtained that the melting and crystallization behaviors of PHB are significantly affected by the extent of thermo degradation which depends on the heating temperature and time used. Moreover, the endothermic peak shown at a temperature higher than the usually melting temperature obtained from PHB during DSC heating scan is determined to be mainly related to the cold-recrystallization during scan rather than the melt-recrystallization.