||針對微生物發酵生產聚酯塑膠PHB, PHBV在不同環境下的降解做一探討。影響材料降解的因素很多，包括環境類型、微生物種類以及其活性、還有溫度、水分、所使用高分子材料結構及其表面組成型態。本研究利用乾式程序、濕式程序以及熱壓程序等不同加工方法將PHB, PHBV製成結晶度、結構、分子量以及孔隙度皆不同的薄膜，將薄膜浸入含有0.04g/dl溶菌素的pH7緩衝溶液中，於37.5℃下進行降解實驗。並於不同降解時間取出薄膜進行重量測試、分子量測量及熱重分析。結果發現於49天內不管是PHB或PHBV，重量幾乎不變，但是分子量下降，熱壓製備的PHB下降速率遠比熱壓製備的PHBV快。在熱重分析實驗中，於氮氣環境下，觀測其最大裂解溫度(Tmax)、起始裂解溫度(Tonset)及剩餘碳渣量(char)，並利用Ozawa數學模型求出其裂解活化能。
The degradability of bacterial plastics, poly(3-hydroxybutyrate) (PHB) and poly(3-hydroxybutyrate-co-hydroxyvalerate) (PHBV), was investigated. Three different processes were employed to produce PHB and PHBV films with different structures and morphologies such as crystallinity, molecular weight, porosity and surface morphology, The degradation experiment was undertaken by immersing sample films into a pH7 buffer solution containing 0.04 g/dl lysozyme at 37.5 degree C. It was observed that the weight of PHB or PHBV film was almost unchanged; but the molecular weight decreased with time up to 49 days, where the decreasing rate was faster for PHB. Thermal gravimetric analysis revealed that the onset degradation temperatures for PHB and PHBV were 258 degree C and 256 degree C, respectively, at a heating rate of 10 degree C/min. The char yield was near zero for both PHB and PHBV at 400 degree C. By using ozawa method, the activation energies of degradation for PHB and PHBV were 111kJ/mol and 119kJ/mol, respectively.