- 學位論文
聚乳酸之正溫度係數效應之相關研究
The Study of Positive Temperature Coefficient Effect of Polylactide Acid
摘要
本篇研究主要是探討結晶性對高分子其正溫度係數（Positive Temperature Coefficient,PTC）效應之影響，本實驗是以聚乳酸（PLA）為母體基質，碳黑（CB）作為導電填充物，利用塑譜儀（PLASTOGRAPH）使高分子在熔融狀態下進行均勻混煉。當混煉完成之後，其高分子複合材料具有良好的導電性質。其中PTC效應即是電阻值隨著溫度上升而升高，當溫度上升到關鍵溫度時，其電阻值會有大幅上升的現象因而形成不良導體造成斷電之效果。利用其PTC效應可應用在電流保護或是過熱保護裝置上。 其中複合導電高分子材料的導電性主要來自於導電填充物所形成的導電通路。在未經過摻合任何導電填充物之前高分子通常為一個絕緣材料，當導電填充物摻入高分子之中，其導電性會隨著填充量的增加而上升。 本研究中利用摻入不同的成分以及不同的冷卻速率處理等因素，來觀察對其複合材料之PTC效應及結晶性的影響。藉由高阻計、微分熱掃瞄卡計（DSC）、廣角X光繞射（WAXD）及掃描式電子顯微鏡（SEM）等儀器來分析複合導電材料之導電、結晶等性質。
並列摘要
This experiment uses the polylactide acid (PLA) as a host material, carbon black (CB) as the pack conductors and adds a small amount of multi-walled carbon nanotubes (MWNTs). Then the polymers were mixed under the state in melting by a Brabender Plastograph, and we found that the polymers composite has a good conductive. The main direction of this research is to observe the composite Positive Temperature Coefficient (PTC) and Negative Temperature coefficient (NTC) effect that relates to concentration of carbon black and carbon nanotubes. PTC effect will make the resistance value rise while the temperature rises, and can apply to the overheated protector. On the contrary, NTC effect will make the resistance value down while the temperature rises. The former experiment usually uses the high density polyethylene (HDPE) and the carbon black (CB) as the composite. Now we replace the polylactide acid (PLA) with the high density polyethylene (HDPE) and see what will be at the end. Polylactide acid is the biodegradable polymer which can reduce the environmental pollution. To add a small amount of carbon nanotubes in composite hoping improve conductive.