聚-3-羥基丁酸酯之接枝改質與性質探討

The Study of the Thermal Properties of the Grafted Poly-3-hydroxybutyrate

林宜徹(Yi-Che Lin)

指導教授 ： 洪信國

元智大學/工程學院/化學工程與材料科學學系/碩士(2006年)

摘要

本研究是探討不同接枝方法將丁烯二酸酐（MA）接枝於聚-3-羥基丁酸酯（PHB）其結晶行為與熱穩定性。由TGA數據證實，經過純化的PHB提高裂解溫度，使熱穩定性變佳，不易因受熱而使分子量降低，進而提高結晶速率、熔融溫度和結晶率。利用酸價分析得知三種不同的接枝方法均可有效的接枝MA，且隨著起始劑和MA量的增加，接枝率也隨之提高。接枝MA有助於提高裂解溫度，主要是因側鏈接枝MA後，會產生立體障礙，進而阻止PHB形成六環狀中間物而逐漸斷鏈裂解，也使結晶速率、熔融溫度和結晶率提高。而未去除殘餘MA和BPO則會使PHB斷鏈裂解降低分子量，導致結晶不完全，而降低結晶速率、熔融溫度和結晶率，且熔融峰為雙重熔融峰。三種不同接枝方法中，以球磨接枝有較佳的熱穩定性、結晶行為和分子量。

關鍵字

聚-3-羥基丁酸酯 ； 丁烯二酸酐 ； 接枝 ； 結晶行為 ； 熱穩定性

並列摘要

The crystallization behavior and the thermal stability of the maleic anhydride (MA) grafted poly-3-hydroxybutyrates (PHB) were studied by using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and gel permeation chromatography (GPC). The results of TGA and DSC indicated that the purified PHB had a better thermal stability, a faster crystallization rater, and a higher melting temperature than the pristine PHB. From DSC and GPC analyses, it was obtained that the PHB degraded after a short exposure at the elevated temperature and which resulted in the decreases of the molecular weight, the melting temperature, and the crystallization rate. The MA was effectively grafted on the PHB by solution grafting, melt grafting, and mechanical grafting methods. The degree of MA grafted was increased with increasing the amounts of the initiator and MA. The thermal stability of the PHB was significantly enhanced by the MA grafted because the degradation reaction was blocked by the steric hindrance of the grafted MA. Additionally, a faster crystallization rater and a higher melting temperature were obtained from the MA grafted PHB. Nonetheless, the residual MA and initiator could lead to the early degradation of PHB. The PHB grafted with the mechanical grafting methods had the best thermal stability than those prepared by other two methods.

並列關鍵字

Poly-3-hydroxybutyrate ； maleic anhydride ； grafting ； crystallization ； thermal stability

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