環氧樹脂/聚氧化二甲苯摻合體反應性、相行為及機械性質之研究; Study on the Reactivity, Phase Behavior and Mechanical Property of Epoxy/Polyphenylene Oxide Blend

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題名:	環氧樹脂/聚氧化二甲苯摻合體反應性、相行為及機械性質之研究;Study on the Reactivity, Phase Behavior and Mechanical Property of Epoxy/Polyphenylene Oxide Blend
作者:	吳紹榮;Shao-Jung Wu
貢獻者:	化學工程與材料工程研究所
關鍵詞:	反應動力;相分離;摻合;聚氧化二甲苯;環氧樹脂;複合材料;reaction kinetic;phase separation;blend;polyphenylene oxide;epoxy;composite
日期:	2000-06-14
上傳時間:	2009-09-21 12:17:05 (UTC+8)
出版者:	國立中央大學圖書館
摘要:	本研究第一部分是以熱熔融法摻合聚氧化二甲苯 (PPO) 於氰酸酯硬化之環氧樹脂中來探討摻合體熱性質、機械性質與相行為。由DSC實驗得知，摻合體的反應起始溫度隨著PPO的含量增加而降低，且反應之總放熱量卻隨著PPO增加而下降。環氧樹脂/PPO系統之硬化遵守著自動催化反應動力模式，但是在此混合系統中之硬化反應速率高於純環氧樹脂系統。環氧樹脂/PPO系統中有較高的反應速率原因是由於聚氧化二甲苯的末端OH基會催化環氧樹脂與氰酸酯的硬化反應。FTIR與NMR分析顯示特性官能基（如環氧基、氰酸酯基）的反應隨PPO增加而加速並且有coreaction 產生，例如cyanate-hydroxyl addition (imidocarbonate, carbamate)，epoxy-cyanate addition (oxazolidinone)等。由SEM與DMA發現摻合體相型態與聚氧化二甲苯的含量有關。當PPO含量低時，相分離是經由nucleation and growth (NG) 進行。PPO含量高時，相分離是經由spinodal相分離模式。當PPO含量大於20 phr時，系統的相反轉開使產生。當PPO含量到達50 phr時，形成PPO為基材連續相，環氧樹脂為分散相。摻合體的抗張強度及模數僅有些許變化，但是韌性卻大幅提升，由其是在系統開使相反轉現象時特別明顯，原因是PPO的延展性及塑性形變造成的。環氧樹脂的介電常數也隨PPO的增加而下降。此外添加反應性單體三丙烯基三聚氰酸鹽 (Triallylisocyanurate, TAIC) 可改善摻合體的相容性和抗溶劑性。第二部分是以分散法摻合Dicyandiamide (DICY) 硬化之環氧樹脂和PPO，來探討其韌性、熱性質、動態黏彈、介電常數和相形態等。由分析中得知摻合PPO提升了摻合體的韌性與絕緣性質，而且抗張強度及模數並未因PPO之摻合而改變；PPO添加量低的摻合體中，PPO粒子有聚集發生；不過在PPO添加量高的摻合體中，粒子間皆有互相連結情形發生，形成PPO與環氧樹脂的共連續相。由動態機械分析 (DMA) 得知摻合體會隨著PPO添加量的增加，其兩相 (環氧樹脂相和PPO相) 的玻璃轉化溫度有向內轉移的現象，產生此現象的原因可能是摻合體在混合及硬化過程中，環氧樹脂比起硬化劑dicy更容易溶於PPO相，結果是較多的環氧樹脂、較少的dicy溶於PPO相，導致PPO相的塑化作用。PPO相的Tg大幅下降可證實這個觀點，同時dicy濃度在兩相中分配不均勻，使得環氧樹脂相的dicy濃度較高，造成環氧樹脂相的Tg點提升。此外，我們添加三丙基烯基三聚氰酸鹽 (TAIC) 於摻合體中，可改善摻合體之相容性及抗溶劑性。在破裂能量方面，隨著TAIC含量的增加而提升。在絕緣電性方面，隨著TAIC含量增加，其介電常數明顯下降。在TGA分析中，在最大裂解速率溫度隨著TAIC含量增加而提高。第三部分是環氧樹脂/PPO摻合體與高功能克維拉纖維製成複合材料，其相分離的模式不同於純摻合體樹脂。當有纖維存在時，相分離過程中環氧樹脂會往極性的纖維表面移動，形成epoxy-coated fiber的相形態，所以microbond的界面性質並不會因PPO的存在而下降。在複合材料積層板中，環氧樹脂會大量聚集在富纖維區域，形成epoxy-coated fiber分佈於PPO相中，此種相形態對於複合材料的破壞韌性、機械性質有正面的影響。 Cure behavior, miscibility and phase separation have been studied in blends of polyphenylene oxide (PPO) with diglycidyl ether of bisphenol A (DGEBA) resin and cyanate ester hardener. An autocatalytic mechanism is observed for the epoxy/PPO blends and the neat epoxy. It is also found that the epoxy/PPO blends react faster than the neat epoxy. The effects of PPO content on the cure behavior in the cyanate ester cured epoxy were investigated with FTIR. FTIR analysis reveals that the cyanate functional group reactions are accelerated by adding PPO and indicates that several coreactions have occurred, such as cyanate-hydroxyl addition and epoxy-cyanate addition. This is caused by the reaction of cyanate ester with PPO phenolic end-group and water yielding imidocarbonate and carbamate intermediate which can react with cyanate ester to form cyanurate. Then the cyanurate can further react with epoxy resin. During cure, the epoxy resin is polymerized and the reaction-induced phase separation is accompanied by phase inversion upon the concentration of PPO greater than 50 phr. At low PPO content, the phase separation takes place via nucleation and growth (NG). At high PPO content, the phase separation takes place via spinodal decomposition (SD). The dynamic mechanical measurements indicate that the two-phase character and partial mixing existed in all the mixtures. The fracture toughness (GIC) and thermal mechanical property are improved by PPO content. However, the two-phase particulate morphology is not uniform especially at a low PPO content. In order to improve the uniformity and miscibility, triallylisocyanurate (TAIC) is evaluated as an in situ compatibilizer for epoxy/PPO blends. TAIC is miscible in epoxy and the PPO chains are bound to TAIC network. SEM observations show that adding TAIC improve the miscibility and solvent resistance of the epoxy/PPO blends. A series of blends has been prepared by adding a polyphenylene oxide, in varying proportions, to an epoxy resin cured with dicyandiamide. All the materials show two-phase morphology when characterized by SEM and DMA. The SEM and DMA indicate that partial mixing exists in all the blends especially in high PPO content. It implies that the epoxy oligomer or low crosslinking density epoxy exists in PPO phase after curing. The tensile strength and modulus of these blends are nearly independent of PPO content. While the fracture toughness (GIC) is improved by PPO content. Furthermore, the dielectric constant decreases with increasing PPO content in a linear fashion. However, two-phase particulate morphology is not uniform. In order to improve the uniformity and miscibility, triallylisocyanurate (TAIC) has been used as an in situ compatibilizer for the polymer blends of epoxy and PPO. SEM and DMA reveal the improvement of miscibility and solvent resistant in this system. The fracture toughness and dielectric constant of these TAIC-modified systems are also improved by adding TAIC (0-20 phr). The morphology of the fiber-rich areas in the composite is different from that of the epoxy/PPO blend without Kevlar fiber. In the pure polymer blends for high PPO content (30 and 50 phr), phase separation and phase inversion are observed. In the composites, the majority of the epoxy resin migrates to the polar fiber surface resulting in the epoxy-coated fibers. So the interfacial shear strength (IFSS) between Kevlar fiber and epoxy/PPO blends is almost the same as that between Kevlar fiber and neat epoxy. The presence of PPO does not affect the interfacial property in the epoxy/PPO/fiber composite. So the interlaminar shear strength (ILSS) increase with the PPO content is due to an increase in the composite's ductility or toughness.
顯示於類別:	[化學工程與材料工程研究所] 博碩士論文

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