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標題: | VAE乳液結構性質分析 Study on Structure and Properties for Vinyl Acetate-Ethylene Copolymer from Emulsion Polymerization |
作者: | Yu-Ho Chen 陳俞合 |
指導教授: | 童世煌(Shih-Huang Tung) |
關鍵字: | 醋酸乙烯酯-乙烯共聚物乳液,乳化聚合,玻璃轉移溫度,組成結構, vinyl acetate ethylene (VAE) emulsions,emulsion polymerization,glass transition temperature,composition,structure, |
出版年 : | 2018 |
學位: | 碩士 |
摘要: | 醋酸乙烯酯和乙烯共聚物(Vinyl Acetate-Ethylene Copolymer, VAE)是工業上應用極廣的產品,經常作為黏合劑使用。VAE乳液是由乳化聚合方式生產,本研究主要針對氧化還原起始法(redox)所合成的VAE乳液做系統性的分析,乳化聚合是製備聚合物膠乳最常見方式,其中基本的成分包括水、低水溶性單體、起始劑和界面活性劑。我們在聚合過程中不同反應時間點取樣,探討VAE乳液固含量、粒徑大小與分佈、流變行為隨著反應時間的變化;藉由熱分析、元素分析、X光散射實驗得知乳液組成隨時間的變化為醋酸乙烯酯先上升後下降,而乙烯組成先下降後上升,在物性分析實驗結果都與VAE乳液組成有關。另一個重要發現為VAE乳液存有兩個玻璃轉移溫度,溫度區間15°C ~ 25°C的玻璃轉移溫度有較大的熱流量,由富含醋酸乙烯酯的無定形結構所產生;溫度-20°C左右的玻璃轉移溫度較不明顯,並且有較低的溫度值,可能含有比較多一些的乙烯組成。最後我們透過1H NMR圖譜上結果推測分支路徑並對此建立VAE乳液的反應機制。 Emulsions of vinyl acetate-ethylene (VAE) copolymers have been widely used in industry as adhesives. In this study, we investigate VAE emulsions which were prepared by emulsion polymerization in the presence of a redox initiator. The emulsion polymerization is the most common way to prepare polymer latex, and the basic components include water, poorly water-soluble monomers, initiators, and surfactants. We analyzed the samples at different reaction time during the polymerization process to investigate the solid content, particle size and distribution, and rheological behavior of VAE emulsions. Through the thermal analysis, elemental analysis, and X-ray scattering experiments, we found that the experimental results are closely related to the VAE composition, and the fraction of vinyl acetate in VAE first rises and then decreases with time, while that of ethylene decreases first and then rises. Another important result is that VAE shows two glass transition temperatures. The main glass transition is between 15°C and 25°C , which is caused by the amorphous structure of the vinyl acetate-rich segments. The glass transition at lower temperature, around -20°C, is less obvious in the DSC curve, which is caused by more ethylene composition. Finally, we determined the branching route of VAE chains through the analyses of the 1H NMR spectrum and proposed the reaction mechanism for VAE emulsion. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/79111 |
DOI: | 10.6342/NTU201802782 |
全文授權: | 有償授權 |
電子全文公開日期: | 2023-08-10 |
顯示於系所單位: | 高分子科學與工程學研究所 |
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