- 學位論文
生物可分解高分子PHB耐熱改質之研究
Study on the Improvement of Thermal Properties of Biodegradable Polymer PHB
摘要
PHA又稱聚羥基烷酸酯(polyhydroxyalkanoate)主要是經由多種菌種在缺乏必要的養分或是存在於過量碳源環境下，細菌於細胞內部生產累積作為儲存能量所合成之聚酯類。由於其結構及性能與聚丙烯類似，且具有生物相容性、生物可分解性及熱可塑性等重要性質，故為主要生物可分解性高分子材料之一。但因熱裂解的關係導致加工困難， 因此本研究將對PHB (polyhydroxybutyrate，PHA之一種)利用一種雙功能既含有活性異氰酸酯基和可聚合雙鍵的新型聚合物單體，AOI (2-acryloyloxyethyl isocyanate)，來進行改質，提昇其耐熱性。隨後再以溶膠-凝膠法導入奈米SiO2製成奈米複合材料，經實驗得到以下結論。 PHB與AOI共聚可有效改善其耐熱性質，熱裂解溫度可達297℃，可製備出能耐熱的PHB材料。因為改質後含有polyurethane結構且分子鏈間具有交聯結構，而使機械性質有所改進，抗拉強度在改質後提高約2倍，斷裂伸長率也提高約2倍。隨後在導入奈米SiO2的實驗中得知奈米SiO2也會提升其耐熱性質，熱裂解溫度可達306℃。在機械性質方面，SiO2的添加可有效增加機械性質，但隨著添加量改變而有先增加後減少的趨勢，這可能導因於SiO2添加量較多時會有微相分離，造成機械強度略為下降。
並列摘要
Polyhydroxyalkanoate (PHA) often used as a biomedical material because it is biodegradable, biocompatible, but the mechanical and thermal properties need to be improved for biomedical applications. In order to improve the thermal properties of biodegradable PHA, various reaction conditions were studied. We have modified polyhydroxybutyrate (PHB), one kind of PHA, by reacting with acryloyloxyethyl isocyanate (AOI). The prepared PHB material has markedly improved thermal properties. The thermal decomposition temperature can reach 297℃. Due to the urethane structure of polymer materials, the mechanical properties also improved. Tensile strength increased 2 times and elongation at break also increased by 2 times when compared to neat PHB. Thus, this modified PHB biodegradable polymer may have greater application as a biomedical material with improved thermal and mechanical properties. PHB nanocomposites can be prepared by a sol-gel process. The thermal decomposition temperature improves to 306℃, the mechanical properties also improved. However, at higher silica content, thermal and mechanical properties were reduced due to the micro-phase separation.