改質聚-3-羥基丁酸酯之熱性質探討

Abstract

The thermal degradation and crystallization behaviors of the maleic acid (MAA) and exo-3,6-epoxy-1,2,3,6-tetrahydrophthalic anhydride (ETA) grafted poly-3-hydroxybutyrates were studied by using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), gas chromatography (GC), and gel permeation chromatography (GPC). The result of GC indicated that MAA and ETA could be effectively grafted onto PHB by the mechanical grinding method. The grafting amount of MAA was greater than that of ETA due to the difference in chemical structures. From DSC analyses, the grafted PHB had a larger crystallinity, a faster crystallization rate, and a higher melting temperature than the as-received PHB because all grafted PHB had a larger molecular weight and a better thermal stability. It was confirmed by TGA that PHB material had the much higher thermal degradation temperature after grafted. This was attributed to the steric hindrance in the formation of six-member ring during the degradation reaction by the grafted MAA and ETA. The degradation kinetic parameters, i. e., the activation energy, the reaction order, and the frequency factor, of PHB were all changed with respect to the grafting chemicals.