- 學位論文
熱處理條件對聚乳酸 /二氧化矽奈米複合物之熱性質的影響
Influence of heat-treatments on the thermal properties of PLA (Polylactic acid) / silica nanocomposites
摘要
本研究利用機械熔融生產聚乳酸/奈米二氧化矽粒子複合材料，並探討其熱處理條件對複合材料的影響，並經由數據分析與結晶動力學的方法，推測奈米二氧化矽粒子，在聚乳酸基材中扮演的角色與作用。 由DSC所呈現結果顯示，明顯的熔融結晶峰產生，隨著奈米二氧化矽添加，熔融結晶峰往高溫偏移，且結晶度也跟著增加。由此可知奈米二氧化矽對於PLA來說，是一個很好的晶核劑。經由TGA證實，添加3 wt% nano-SiO2，可以增加熱穩定性。並不會因PLA轉酯化反應或熱裂解時間增加，而有所改變。由POM結果可以發現，在相同nano-SiO2含量下，不同熱降解時間，隨著時間增加，在較高溫度下，可以發現較多的晶核。奈米二氧化矽奈米粒子因其奈米尺寸特性，提供複合材料更多的表面積，可阻礙高分子膜材 (matrix) 中高分子鏈的運動，進而增加熱穩定性，增加成核速率與熱穩定性，也是很好的晶核劑。尤其是添加3 wt% nano-SiO2對PLA有最好的效果。SEM與EDS結果顯示膜材中，並不依熱降解時間改變，或因奈米二氧化矽含量改變而有顯著的團聚現象，證明利用機械熔融摻混法 (mechanical melt blending)，配合分散劑的使用，製成奈米複合膜材，可以有良好的分散性。
並列摘要
Biodegradable PLA/silica nanocomposites were prepared by melt blending. The influence of melting time on the thermal properties of poly(L-lactic acid) (PLLA) was studied with differential scanning calorimetry (DSC) and thermogravimetric analyses (TGA). The thermo-degradation and the formation of multiple-endothermic behaviors of the PLA matrix during heating are studied with DSC. The single exothermic peak could be observed at cooling rate of 2 oC/min, after melting at different condition. The obtained peak temperature and degrees of crystallinity dramatically increased with an increase of melting time. The DSC results reveal that SiO2 is not only a nucleating agent, but also an interrupted stuff for the crystalline behavior of PLA. Crystalline structure and crystalline behavior were observed by POM. Scanning electron microscopy results show that the silica nanoparties were uniformly distributed in the PLA matrix for filler contents below 3 wt%.