【摘要】：纖維增強(qiáng)聚合物(FRP)復(fù)合材料具有輕質(zhì)高強(qiáng)、耐腐蝕、易加工性等優(yōu)點,被廣泛地應(yīng)用于土木工程結(jié)構(gòu)的加固、修復(fù)與改造。由于土木工程結(jié)構(gòu)服役環(huán)境復(fù)雜(如水或強(qiáng)堿溶液浸泡),FRP在服役過程中會吸收水分,引起性能發(fā)生退化,并導(dǎo)致結(jié)構(gòu)的長期服役安全性問題。FRP主要由纖維與樹脂基體組成,同纖維(如碳纖維)相比,樹脂基體更易受環(huán)境的侵蝕。因此,研究樹脂基體在水或強(qiáng)堿溶液浸泡條件下的性能退化規(guī)律與機(jī)理,對明確FRP的耐久性能及其性能改進(jìn),從而推動FRP的安全應(yīng)用具有重要意義。本文采用試驗測試與分子動力學(xué)模擬方法,研究了環(huán)氧樹脂基體在水或強(qiáng)堿溶液浸泡條件下的水吸收與性能的退化,研究內(nèi)容主要包括:1)環(huán)氧樹脂在20℃、40℃與60℃蒸餾水或強(qiáng)堿溶液(p H=12.5,模擬混凝土滲出液)浸泡過程中的水吸收與擴(kuò)散規(guī)律,以及水吸收引起的樹脂基體熱力學(xué)性能、自由體積分?jǐn)?shù)及化學(xué)組成的變化;2)基于光纖光柵監(jiān)測技術(shù),測試水吸收導(dǎo)致的環(huán)氧樹脂基體的溶脹;3)最后,利用分子動力學(xué)軟件,模擬分析了水分子在樹脂基體內(nèi)的吸收與擴(kuò)散過程及其塑化作用。實驗結(jié)果表明,浸泡過程中,環(huán)氧樹脂基體的吸水過程符合經(jīng)典的Fick模型;樹脂基體的平衡吸水率和擴(kuò)散系數(shù)隨著浸泡溫度的升高而增大;吸水對樹脂產(chǎn)生明顯的塑化作用。紅外分析結(jié)果表明,長期水或強(qiáng)堿溶液浸泡對環(huán)氧樹脂內(nèi)部的化學(xué)結(jié)構(gòu)影響較小,并沒有產(chǎn)生明顯的水解反應(yīng)。光纖光柵監(jiān)測結(jié)果表明,浸水后一個月內(nèi),樹脂膨脹應(yīng)變(溶脹作用)增長較快,而隨后趨于平衡。通過分子動力學(xué)建立了環(huán)氧樹脂的分子模型,模擬分析了樹脂基體的玻璃化轉(zhuǎn)變以及水吸收對樹脂的塑化作用;在較低吸水率情況下,氫鍵能較大,體系密度增加,隨著吸水率提高,密度逐漸降低,水分子的擴(kuò)散系數(shù)增大,局部鏈運(yùn)動加快,表明氫鍵能對于樹脂性能有重要的影響。
[Abstract]:Fiber reinforced polymer (FRP) composites have been widely used in the reinforcement, repair and transformation of civil engineering structures because of their advantages of light weight and high strength, corrosion resistance and easy processing. Due to the complex service environment of civil engineering structures (such as water or strong alkali solution immersion), FRP will absorb water during service, resulting in performance degradation, FRP is mainly composed of fiber and resin matrix, which is more vulnerable to environmental erosion than fiber (such as carbon fiber). Therefore, it is of great significance to study the degradation law and mechanism of resin matrix under the condition of soaking in water or strong alkali solution in order to clarify the durability and performance improvement of FRP, so as to promote the safe application of FRP. In this paper, the water absorption and degradation of epoxy resin matrix under the condition of soaking in water or strong alkali solution were studied by means of experimental test and molecular dynamics simulation. The main research contents are as follows: 1) epoxy resin at 20 鈩，

本文編號：2496012