本研究利用溶液摻混與熔融摻混法製備生物可分解塑膠聚羥基丁酯與澱粉接枝聚醋酸乙烯酯PHB/PVAc-modified Starch聚掺合體，探討其相容性並測量其性質，因為PHB成本過高，於是藉著摻合同樣具有生物可分解性但價格便宜的澱粉以大幅降低成本。而為了增加澱粉和PHB的相容性，於是將和PHB相容的PVAc接枝到澱粉上，為了增加接枝比值，將硝酸銨鈰起始劑溶解在不同濃度之硝酸溶液中，探討硝酸濃度對單體轉化率，接枝效率和接枝比值的影響。將接枝比值最高(0.223)的改質澱粉(SV3)直接和PHB以不同比例進行摻混，以TGA測定聚掺合體之熱裂解溫度、DSC觀察玻璃轉移溫度(Tg)、結晶溫度(Tc)和熔點(Tm)、DMA測定Tg及固態機械性質、並以SEM觀察聚摻合物相形態。結果發現在0.5M之硝酸溶液中，單體轉化率和接枝比値都達到最高，分別為93.6%和0.223。另外也測量了接枝產物的熱轉移性質、熱重損失及分子量。 由DSC和DMA測試得知所有不同組成的PHB/SV3摻混系統都呈現單一Tg，同時Tg隨著SV3比例的增加而增加，因此PHB和SV3為一相容系統，利用Gordon-Taylor方程式去描述PHB/PVAc及溶液摻混和熔融摻混之PHB/SV3 (SV3為澱粉接枝PVAc產物)的Tg和組成之關係，均能符合，所求出之參數k值分別為0.87、0.32和0.35。TGA測試結果顯示掺合體是呈現出三階段的熱裂解行為，各階段主要是由PHB及SV3所表現出來的裂解行為，第一階段為PHB成份的熱裂解，微分裂解峯溫度都在288~305 oC之間，隨著SV3組成的增加而增加，第二階段及第三階段熱裂解則是由SV3成分所造成，焦碳殘餘量則隨著SV3比例之增加而增加，由DMA測試得知在25oC時PHB的儲存模數為3.12GPa，而SV3的儲存模數為1.49GPa；PHB/SV3聚掺合體的模數則隨著SV3組成的增加而下降，另外隨著SV3組成的增加，掺合體的損耗正切峯面積亦隨之增加，顯示材料的韌性因為添加了澱粉接枝聚醋酸乙烯酯而增加。改善了原先PHB的脆性。 In this study, the preparation and properties of poly-3-hydroxybutyrate(PHB) blended with modified soluble starch are discussed. PHB is hard and brittle due to its high degree of crystallinity and high melting point. Therefore, it is desirable to blend PHB with other polymers to improve its toughness and processing window. In order to increase the miscibility between PHB and starch, vinyl acetate monomer was graft polymerized onto starch with a redox initiator, cerium ammonium nitrate (CAN). CAN was dissolved in varying concentration of nitric acid to discuss its impact on the monomer conversion, grafting ration and grafting efficiency and to find the optimum grafting ratio. The maximum monomer conversion and grafting ratio were 93.6% and 0.223, respectively, in this study. The composition prepared in this research are as follows: PHB/SV3 =100/0, 80/20, 60/40 , 40/60 , 20/80, 0/100 (SV3 is the reaction product and its grafting ratio is 0.223). Thermal degradation behavior was analyzed by thermal gravimetric analysis, the glass transition temperature Tg and the degree of crystallization of the blends were observed by differential scanning calorimetry. The dynamic mechanical properties of blends were analyzed and their morphology were characterized by the scanning electron microscopy.
