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    題名: 裂縫方位對溶劑引發聚甲基丙烯酸甲酯的裂縫癒合影響
    其他題名: The effect of crack orientation on solvent-induced crack healing in poly(methyl methacrylate)
    作者: 何金新;Ho, Jin-shin
    貢獻者: 淡江大學機械與機電工程學系博士班
    林清彬;Lin, Ching-bin
    關鍵詞: 平行裂縫癒合;垂直裂縫癒合;聚甲基丙烯酸甲酯;甲醇;乙醇;重疊加成質傳;溶劑影響區.;Line - and Cross - Crack healing;Poly(Methyl Methacrylate);Methanol;Ethanol;Superposition;Solvent Affected Zone (SAZ).
    日期: 2007
    上傳時間: 2010-01-11 06:22:58 (UTC+8)
    摘要: 本研究已探討聚甲基丙烯酸甲酯之平行裂縫(垂直於拉伸軸向之試片中央位置處做一平行裂縫)及垂直裂縫(就已癒合之平行裂縫試片,垂直於已平行裂縫癒合處之中央位置再做一平行裂縫)等兩方位,經過40℃ ~ 60℃甲、乙醇溶劑的質傳引發癒合後之物性與機性的改變。研究中發現,經過甲、乙醇質傳處裡後聚甲基丙烯酸甲酯的玻璃轉換溫度會降低,當有效玻璃轉換溫度低於操作溫度時,上述兩種裂縫的自我癒合均會發生,其中裂縫閉合率(crack closure rate)是常數,且垂直裂縫之閉合率大於平行裂縫之閉合率。由拉伸破裂表面型態和機械強度的分析知道裂縫癒合分成兩個階段:潤濕或擴散。癒合後試片的拉伸破斷應力會隨著甲、乙醇的體積分率增加而上升。聚甲基丙烯酸甲酯之平行裂縫和垂直裂縫癒合的拉伸破斷應力,經由甲醇質傳後可恢復到與原材料相同;而乙醇質傳後僅垂直裂縫癒合可恢復到與原材料相同。甲、乙醇兩者的垂直裂縫癒合的拉伸破斷應力均大於平行裂縫癒合的拉伸破斷應力,並且垂直裂縫癒合後的拉伸破斷應力比平行裂縫癒合後大。甲、乙醇質傳到聚甲基丙烯酸甲酯會產生陡峭面,平行裂縫癒合時的陡峭面是直線,而垂直裂縫癒合時的陡峭面則會在平行裂縫癒合處形成內凹現象,且內凹的曲率半徑隨質傳時間增加而上升直到無限大,另外垂直裂縫癒合之陡峭面前進的速度比平行裂縫癒合的速度還快。垂直裂縫癒合之分子鏈經兩次溶劑處理的重疊加成(superposition)質傳與溶劑影響區(solvent affected zone) (SAZ)的影響,在垂直裂縫的癒合交界處會產生塑性應變區,以阻撓裂縫前進。待拉伸應力大於此一塑性應變時,垂直裂縫癒合拉伸試片即刻斷裂。此一塑性應變區現象為平行裂縫癒合所没有的。
    The line-and the cross-crack healing of Poly(methyl methacrylate)(PMMA) under the methanol or ethanol treatment at 40℃ ~ 60℃ have been studied. The cross-crack means that the crack plane is vertical to the line-crack healed. The glass transition temperature of PMMA is reduced after the methanol or ethanol treatment. Both crack healings only occur at the effective glass transition temperature lower than the transport temperature. Both crack closure rates are constant. The closure rate of the cross-crack is higher than that of the line-crack. The analyses of the surface morphology and mechanical strength show that there are also two stages for crack healing which is wetting and diffusion. The tensile fracture stress of the healed specimen increases with a rise in volume fraction of the absorbing methanol or ethanol. The tensile fracture stress of healed PMMA with line- or cross-crack can be recovered to the virgin material during methanol treatment but cross-crack only can be recovered to the virgin material for ethanol treatment. The tensile fracture stress of healed PMMA with cross-crack is larger than that with the line-crack. The shape of sharp front healed from the line-crack is straight line but from the cross-crack perform a inward concave which is parallel to the healed place. The curvature radius of inward concave rises to infinity with time. The sharp front of healed PMMA with the cross-crack moves faster than that with the line-crack.
    顯示於類別:[機械與機電工程學系暨研究所] 學位論文

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