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題名 | The Effects of Polymerisation Route on the Phase Separation and Physical Properties of Polyurethane Elastomers=加工程序對PU彈性體之相分離及物性之影響 |
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作 者 | 李大剛; | 書刊名 | 宜蘭農工學報 |
卷期 | 3 1991.08[民80.08] |
頁次 | 頁133-149 |
分類號 | 467.4 |
關鍵詞 | 分離; 加工; 物性; 程序; 彈性體; |
語文 | 英文(English) |
中文摘要 | 二系列硬段含量為60﹪W/W之PU彈性體,分別使用應用大量催化劑之反應射出成型 (Reaction Injection Moulding,RIM)及不加催化劑之鑄模(hand-cast)加工程序製造。其化 學組成中之硬段由EG╱MDI所組成,而軟段則選用分子量為5,600之聚醚三元醇(M111)、 分子量為2,000之聚醚二元醇(N1256)及M111與N1256以60:40當量比例之混合多元醇為原 料。利用此二系列成品探討改變加工程序及軟段之組成對於產品之相分離現象及物性之影 響。用以鑑定之儀器及方法分別有動態一機械熱分析儀(DMTA)、微分掃瞄熱卡計(DSC)、 拉力實驗及單邊刻痕(SEN)斷裂強度等。 相同化學成份之PU彈性體成品,以RIM加工方法製造之成品與鑄模方式合成之成品有相近之 軟段玻璃轉化溫度(Tg□)在-32℃,但前者有較高之硬段玻璃轉化溫度(Tg□),且有較 高之相分離現象(約10﹪)。當較段成份中之聚醚二元醇成份N1256增加時則PU彈性體成品 之相分離程度會顯著下降,若軟段完全使用N1256則成品則為一完全混合之成品,且只有一 個Tg值存在,其值分別為76℃(RIM-N1256-60)及32 ℃(N1256-60)。 當軟段中之聚醚多元醇由三元醇(M111)轉換為二元醇(N1256),其楊氏模數由589 Mpa 減至331 MPa,但抗撕裂強度(由SEN方法測定)則由3.8增至11.3 KJ╱m□。以RIM製成之 成品較鑄模製造之成品有較高之E□(-30)╱E□(+65)比值,前者對於溫度之依存性較 高,主要歸因於RIM加工程序中使用了大量的催化劑(0.258﹪W╱W之DABCO及0.115﹪W╱ W之DBTDL)及不同之升溫過程所致。同時RIM成品在T>180℃時,其機械性質急速衰退, 是因RIM成品中殘存之催化劑對成品在高溫下有加速分解及熱劣化之作用所致。 |
英文摘要 | A series of segmented copolyurethanes, comprising ethylene glycol/MDI hard segments(60% W/W) dispersed in polyether/MDI soft segments, has been formed by RIM. The polyether used was either a trio1 (Mn=5,600) or a diol (Mn=2,000) or a 60:40 molar equivalent mixture of triol:diol. The effects of varying the polyether on the degree of phase separation and subsequent morphological structure of the copolyurethanes have been investigated using dynamic mechanical analysis, differential scanning calorimetry, tensile stress-strain and single edge notch (SEN) fracture measurements. Comparisions are made between the copolyurethanes formed by RIM using high levels of catalysts and essentially adiabatic conditions, and corresponding materials formed isothermally by hand-casting without catalysts. The catalyst system employed was dibutyl tin dilaurate (DBTDL) and 1,4-Diazabicyclo (2,2,2) Octane (DABCO). The catalysts were added to the polyol blend and their concentration relative to the overall hydroxyl group concentration was maintained constant, at 0.258% W/W DABCO and 0.115% W/W DBTDL per hydroxy equivalent. The RIM materials are shown to have similar values of Tg□ (-32℃) but higher values of Tg□ than corresponding hand-cast materials, indicating higher degrees ( by about 10%) of phase separation in the former. Mixed triol/diol soft segments reduce phase separation markedly so that for diol only systems, completely phasemixed copolyurethanes are obtaines with a single merged Tg at 76 and 32℃, respectively, for RIM and hand-cast materials. As polyol composition changes from triol to diol, the tensile modulus of copolyurethanes decreases by almost a half (589 to 331 MPa), but fracture resistance from SEN data increases by a factor of three (3.8 to 11.3 kJ m□). These observations are in general agreement with other published data(1). The much greater modulus-temperature dependence of RIM-copolyurethanes compared with hand-cast materials is attributed to the use of catalysts and the different processing condition pertaining to the RIM process(2). In addition, the rapid deterioration of mechanical properties of the RIM-materials at elevated temperatures (>180℃) results from the presence of the initial catalysts which promote de-polymerisation and other thermal degradation processes(3). |
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