生物降解性聚乳酸與改質多壁奈米碳管複合材料 之製備及其性質探討

The Preparation and Properties of Biodegradable PLA/Modified Multi-Walled Carbon Nanotubes Nanocomposites

林宛螢(Wan-Ying Lin)

指導教授 ： 石燕鳳

朝陽科技大學/理工學院/應用化學系/碩士(2010年)

摘要

本研究藉由熔融混煉 (Melt-blending) 的方式，將聚乳酸( polylactic acid ，PLA) 與原始碳管、改質碳管進行混掺，獲得奈米複合材料。為了提升多壁奈米碳管在複合材料中的分散性，將碳管表面進行化學修飾，首先將多壁奈米碳管加入 HNO3 溶液中，進行酸化，使碳管表面帶有羧酸 (-COOH) 的官能基，然後再加入十八烷醇 (Stearyl alcohol)，在溫和的條件下， 藉由 N,N’- 二環己基碳二亞胺 (N,N’-dicyclohexylcarbodiimide, DCC) 脫水劑脫水，可得到改質後的碳管 (CNT-C18) ，改質碳管可以分散在 chloroform 、 THF、 DMF…等有機溶劑中。利用溶液法使改質碳管能夠均勻分散於 PLA 中，並同時添加少量的酯交換劑，使碳管能夠與 PLA 之間形成化學鍵結，並且提升複合材料之機械及物理性質，最後以熔融混煉方式製備 PLA/CNT 複合材料，對於複合材料的熱性質、機械性質及導電性質進行探討。
結果顯示， CNT-C18 及添加酯交換劑之改質碳管皆可以均勻分散在聚乳酸中，有效的改善複合材料的機械性質及導電性質。添加3 wt% 的改質碳管及有加酯交換劑的改質碳管之複合材料，在40℃下其儲存模數分別提升了77.4 % 和88.0 %，且在玻璃轉移溫度(Tg)時之損失模數分別提升了43.8 % 和75.6 %。在導電性部分，PLA在添加3 wt% 有加酯交換劑的改質碳管後，其表面電阻由5.30×1012 Ω/cm2 降低到 8.58×10-2 Ω/cm2 ，已可達到靜電消散或抗EMI 的效果，未來將可以應用在電子相關產品上。

關鍵字

聚乳酸 ； 酯交換劑 ； 奈米複合材料 ； 多壁奈米碳管

並列摘要

In this study, polylactic acid / pristine carbon nanotubes or modified carbon nanotubes nanocomposites were prepared by a melt blending method. In order to increase the compatibility between multi-walled carbon nanotubes (CNTs) and polylactic acid (PLA), the surfaces of CNTs were chemically modified. In this study, CNTs were first pre-treated using acid solution (HNO3) to functionalize the CNTs surface with carboxylic groups (-COOH), form the acid-treated carbon nanotubes (CNT-COOH). Subsequently, the stearyl alcohol was grafted onto carboxylic groups with the assistance of dehydrating agent, N,N’-dicyclohexyl-carbodiimide (DCC), then we can obtain the modified CNTs (CNT-C18). The CNT-C18 can be dispersed in organic solvents, such as DMF, THF, and chloroform. Furthermore, the modified carbon nanotubes and PLA were mixed by solution method, and a small amount of ester-exchange agent was added, so that modified carbon nanotubes can be grafted onto PLA chains to enhance mechanical and physical properties of the composites. Finally, the PLA/CNTs nanocomposites were then prepared through melt-blending method. The thermal behaviors, morphology, mechanical properties, conductivity of resultant PLA/CNTs nanocomposites were investigated.
The results show that excellent dispersion of nanotubes in the PLA matrices was achieved. Moreover, an improvement in thermal properties was also observed. Nanocomposite with the addition of 3wt% modified carbon nanotubes and ester-exchange agent modified carbon nanotubes composites, the increments of storage modulus (E'') at 40oC were 77.4% and 88.0%, respectively. And the increments of loss modulus (E'') at glass transition temperature (Tg) were 43.8% and 75.6%, respectively. In the aspect of conductivity, the surface resistivity of the PLA nanocomposites decreased from 5.30×1012 Ω/cm2 to 8.58×10-2 Ω/cm2 after addition of 3wt% ester-exchange agent modified carbon nanotubes. Such modified carbon nanotubes nanocomposites are highly efficient for anti-static purpose, even electrostatic discharge or anti-EMI purpose, which can be applied in electronic materials.

並列關鍵字

ester-exchange agent ； polylactic acid ； nanocomposites ； multi-walled carbon nanotubes

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