聚乳酸-二氧化矽複合材料的結晶行為

Crystallization Behavior of PLLA-SiO2 Composites

梅 愷(KAI MEI)

指導教授 ： 廖文彬

國立臺灣大學/工學院/材料科學與工程學研究所/碩士(2009年)

https://doi.org/10.6342/NTU.2009.03155

摘要

本研究主要探討聚乳酸(PLLA)的結晶結構與結晶動力學。聚乳酸材料在熔融-結晶的過程中，會因為結晶溫度的不同而產生不同的結晶結構，在較高溫度區會形成排列較緊密的結晶結構稱為α結構，相對的在低溫的結晶則是排列較鬆散的α’結構，而中間有一段兩種結構共存的溫度區間，利用XRD、DSC、FTIR等觀察共存區結晶隨時間的變化，發現過程中會先長出結構較緊密的α結構，隨著時間演進慢慢長出α’結構，這兩種結構以動力學機制互相競爭成長。

此外也針對含有D-form的聚乳酸材料和PLA-SiO2複合材料進行研究，D-form單元在結晶時會被晶片排出，故在結晶時需要更久的時間進行，此外PLA較低的平衡熔點促使兩結晶結構的存在溫度往低溫偏移。當加入SiO2顆粒，兩種結構受到的影響程度不同，導致共存區域的結晶競爭模式改變，最後結晶的結果和純PLA有所差異。本論文探討D-form單元以及SiO2添加物對結晶行為的影響，可提供此複合材料相關的應用加工資訊，調控改善我們所需的材料性質。

關鍵字

聚乳酸 ； 結晶動力學 ； 奈米複合材料 ； 二氧化矽顆粒 ； 結晶結構

並列摘要

The research is focus on crystal structure and crystallization kinetics of PLLA. PLLA polymer chains packed closely as α-form at higher crystallization temperature(Tc) from melt, whileα’-form generates at low Tc which packed loosely. However, two crystal structures can exist at some moderate temperatures. It is investigated by X-ray diffraction, DSC, FTIR during the crystallization process at the co-existed Tc. The α structure dominates at the beginning and then α’ structure develops later. The two crystal structures compete in the view of crystallization kinetics.
The PLA which has D-form units on the polymer chain compares with PLLA. The D-form units will be excluded from the lamella of the polymer crystal and result in the lower melting point. The decrease of equilibrium melting point makes change of the existence Tc region of the two crystal structures. When SiO2 particles add into the PLA matrix, different effect on α and α’results in the change of competition model. So the crystallization structure and properties of PLLA can be controlled by D-form units and SiO2 particles. The knowledge of crystallization of PLLA can be used to adjust manufacture condition and achieve good quality which we need .

並列關鍵字

Poly(L-lactide) ； crystallization kinetics ； SiO2 particles ； nano-composite material ； crystal structure

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