利用香蕉纖維補強生物可降解綠色複合材料之探討

A study of biodegradable green composites reinforced by banana fibers

黃千鐘(Chien-Chung Huang)

指導教授 ： 石燕鳳

朝陽科技大學/理工學院/應用化學系/碩士(2009年)

摘要

本研究是藉由雙螺桿熔融混煉(melt blending method)法，將聚乳
酸(Polylactic acid，PLA)與香蕉纖維(banana fiber，BF)進行混掺，利用天然纖維補強高分子主體製備一種新的生物可分解複合材料來改善其原本材料的缺點。同時利用微差掃描卡(Differential Scanning Calorimeter ，DSC) 、傅立葉轉換紅外光譜儀(Fourier Transform Infrared，FTIR)、熱重分析儀(Thermogravimetic Analysis，TGA)、掃描式電子顯微鏡(Scanning Electron Microscopy，SEM)、萬能材料試驗機(Instron Mechanical Tester)等儀器來分析、鑑定在高分子複合材料中，天然纖維的添加對聚乳酸材料性質的影響差異，再進一步探討聚乳酸/香蕉纖維(PLA/BFs)複合材料的熱性質與機械性質。
聚乳酸(PLA)為疏水性高分子，和親水性的香蕉纖維(BFs)界面相容性低，研究中為了增強香蕉纖維在聚乳酸主體中的界面黏著性和分散性，我們將香蕉纖維表面經過有機矽烷類偶合劑(coupling agent)處理。由於矽烷類偶合劑的一端親水一端疏水的特性，改質過後的香蕉纖維可與高分子主體形成Si-O-C 網狀結構鍵結，不但可以增強纖維表面和高分子間的黏著性，並且更降低了纖維本身的吸水性。結果顯示聚乳酸添加偶合劑改質香蕉纖維的複合材料，不僅各項機械性質提高，焦炭含量亦提高。從SEM 圖可看出經過偶合劑處理過的香蕉纖維明顯提高了與聚乳酸主體之間的相容性，使得材料拉伸強度明顯提昇，添加量即使高達60phr 其機械強度仍舊較純聚乳酸佳。此外，添加香蕉纖維可明顯改善聚乳酸原先較差的耐熱性，加入20phr 香蕉纖維複合材料的熱變形溫度(HDT)可從純聚乳酸的62℃提升至130℃，提升了108%，加入40phr 香蕉纖維HDT 更可達到139℃，耐熱性提升了122%。顯示經化學改質後，材料之相容性明顯提升，因此不僅能補強材料之耐熱及機械性質，更進一步能夠有效降低生物可分解塑膠之成本。

關鍵字

聚乳酸 ； 香蕉纖維 ； 偶合劑 ； 複合材料

並列摘要

In this study, the polylactic acid (PLA) / banana fiber(BF)composites were prepared by the melt blending method. BF was adopted to reinforce the polymer matrix and form a new biodegradable composites. The effects of addition of the BF on the PLA matrix, and the thermal and mechanical properties of PLA/BF composites were investigated by Differential Scanning Calorimeter (DSC), Fourier Transform Infrared (FTIR) , Thermogravimetic Analysis(TGA), Scanning
Electron Microscopy (SEM) and Instron mechanical tester.
PLA is a hydrophobic polymer and is not compatible with BFs
which is hydrophilic material. In the research, we use coupling agent to deal with the surface of the banana fiber and to strengthen the interface adhesion and dispersion of the banana fiber in the PLA matrix. Because
the one side of the coupling agent is hydrophobic, and another side is hydrophilic, the silane-treated fiber can form the Si-O-C bond network structure with polymer matrix. Thus, not only can reinforce the adhesion
between fiber surface and polymer, but also decrease the water absorption of the fiber.
The result shows that the addition of silane-treated banana fiber in the PLA can improve the mechanical strength and char yield of the material. Even if the amount of the fiber was up to 60phr, the mechanical strength was still better than that of pure PLA. Moreover, the addition of silane-treated banana fiber can also improve the heat resistance of PLA. Adding of 20phr banana fiber into the composite can increase the HDT of pure PLA from 62℃ to 130℃, the improvement was about 108%. And adding of 40phr banana fiber into the composite can increase the HDT of pure PLA from 62℃ to 139℃, the improvement was about 122%. It shows that compatibility of materials has been improved significantly after chemical modification. Therefore, the addition of silane-treated
banana fiber not only can reinforce the heat-resistant and mechanical properties of the materials, but also can decrease the cost of biodegradable plastic .

並列關鍵字

coupling agent ； Polylactic acid (PLA) ； banana fiber ； composites

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