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標題: A2B3型超分支狀高分子在環氧樹脂增韌上的應用
A2B3 type hyperbranched polymers as toughener for epoxy resins
作者: 周于堯
Chou, Yu-Yao
Contributors: 鄭紀民
化學工程學系所
關鍵字: 環氧樹脂;超分支狀高分子;增韌
Epoxy;Hyperbranched Polymers;Toughener
日期: 2012
Issue Date: 2013-11-21 10:04:56 (UTC+8)
Publisher: 化學工程學系所
摘要: 本論文製備A2+B3型超分支狀高分子,A2單體為diethylenetriamine (DETA),B3單體為脂肪族及芳香族的醇類核心之衍生物,具有反應選擇性azetidine-2,4-dione官能基單體,透過一級胺官能基進行快速開環加成反應,製備出以脂肪族與芳香族核心發展,並含有malonamides之超分支狀高分子(HBPs),藉由FT-IR、1H-NMR、EA、MASS、胺基滴定及GPC的結構鑑定,確定其化學結構的正確性。
第二部份實驗,以DGEBA環氧樹脂為基材,硬化劑為二元胺(DDM;4,4''-diaminodiphenylmethane),利用超分支狀高分子作為增韌劑,用以改善環氧樹脂硬、脆的特性,所合成的HBPs在外圍具有胺基官能基能與環氧基開環反應,將HBPs導入環氧樹脂的系統內並且利用HBPs的結構特性增加環氧樹脂的韌性。利用DSC及TGA分析玻璃轉移溫度(Tg)與熱裂解溫度(Td)之變化,固化物塊材之機械性質藉由三點彎曲測試、衝擊強度試驗來評估,藉由SEM圖觀察斷裂面的型態來探討其增韌的機制。
實驗結果顯示,添加反應型改質劑比起沒有添加的系統明顯具有較好的彎曲延性,但隨著添加的改質劑含量增加,彎曲強度也隨之下降,添加芳香族HBPs比起脂肪族較能維持塊材的機械強度,在10 phr添加量下擁有最大的耐衝擊強度,這是因為所導入的HBPs增加破壞了環氧樹脂本身的結構及交聯密度,透過HBPs內部具有大量空洞和剛性的苯環結構,吸收衝擊能量藉以提升環氧樹脂的衝擊強度。DSC分析顯示添加量的HBPs系統為單一Tg,但Tg範圍隨添加量變寬得知系統處於互容邊緣,增韌材料均勻散佈在環氧樹脂中利用原位增強是其主要的增韌機制,由SEM圖可觀察到混摻後的斷面形態與純樹脂不同,具有大量的裂紋產生及許多類似被撕扯變形所造成的不規則區域。
In this study, we synthesized novel amine-terminated hyperbranched polymalonamides as epoxy reactive modifier from tris(azetidine-2,4-dione) (B3 type monomer) and diethylenetriamine (DETA; A2 type monomer). Two series of tris(azetidine-2,4-dione) monomers compring respective aromatic- and aliphatic-core structure were synthesized from triols (1,1,1-tris(4-hydroxyphenyl)ethane; THPE and trimethylolpropane; TMP) and 4-isocyanato-4''(3,3-dimethyl-2,4-dioxo- acetidino)diphenylmethane; (IDD) We characterized these synthesized reactive modifiers using Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), nuclear magnetic resonance spectroscopy (NMR), elemental analysis, amine titration, mass spectrometry, etc.
During the thermosetting processes, the low viscosity hyperbranched polymers (HBPs) possessing abundant amine groups were covalently embedded into epoxy resin systems. The introduction of HBPs into diglycidyl ether of bisphenol-A (DGEBA) cured with 4,4''-diaminodiphenylmethane (DDM) resulted in epoxy networks exhibiting tunable crosslinking densities, glass transition temperatures (Tgs), flexibilities and toughness. The addition of HBPs significantly increased the values of impact strength by 27% relative to that of the neat epoxy system, while the flexural strength and modulus decreased to some extent. The optimal loadings of HBPs was observed at 10 phr in the aspect of impact strength and bending tests. The miscibility between HBPs and DGEBA domains was investigated by differential scanning calorimeter (DSC) and scanning electron microscopy (SEM). Although all systems showed a single Tg, the broadening of glass transition suggested a marginal miscibility at high HBPs loadings. Fracture surface of SEM exhibited cavitations at center revealing that the interfacial cavitations, and in situ homogeneous reinforcing are the main toughening mechanisms. Furthermore, dynamic mechanical analyses (DMA) also indicated that these reactive modifiers significantly enhanced the toughening properties of epoxy resins.
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