水碱浸泡条件下环氧树脂的性能演化与分子动力学模拟

发布时间：2019-06-10 00:13

【摘要】：纤维增强聚合物(FRP)复合材料具有轻质高强、耐腐蚀、易加工性等优点,被广泛地应用于土木工程结构的加固、修复与改造。由于土木工程结构服役环境复杂(如水或强碱溶液浸泡),FRP在服役过程中会吸收水分,引起性能发生退化,并导致结构的长期服役安全性问题。FRP主要由纤维与树脂基体组成,同纤维(如碳纤维)相比,树脂基体更易受环境的侵蚀。因此,研究树脂基体在水或强碱溶液浸泡条件下的性能退化规律与机理,对明确FRP的耐久性能及其性能改进,从而推动FRP的安全应用具有重要意义。本文采用试验测试与分子动力学模拟方法,研究了环氧树脂基体在水或强碱溶液浸泡条件下的水吸收与性能的退化,研究内容主要包括:1)环氧树脂在20℃、40℃与60℃蒸馏水或强碱溶液(p H=12.5,模拟混凝土渗出液)浸泡过程中的水吸收与扩散规律,以及水吸收引起的树脂基体热力学性能、自由体积分数及化学组成的变化;2)基于光纤光栅监测技术,测试水吸收导致的环氧树脂基体的溶胀;3)最后,利用分子动力学软件,模拟分析了水分子在树脂基体内的吸收与扩散过程及其塑化作用。实验结果表明,浸泡过程中,环氧树脂基体的吸水过程符合经典的Fick模型;树脂基体的平衡吸水率和扩散系数随着浸泡温度的升高而增大;吸水对树脂产生明显的塑化作用。红外分析结果表明,长期水或强碱溶液浸泡对环氧树脂内部的化学结构影响较小,并没有产生明显的水解反应。光纤光栅监测结果表明,浸水后一个月内,树脂膨胀应变(溶胀作用)增长较快,而随后趋于平衡。通过分子动力学建立了环氧树脂的分子模型,模拟分析了树脂基体的玻璃化转变以及水吸收对树脂的塑化作用;在较低吸水率情况下,氢键能较大,体系密度增加,随着吸水率提高,密度逐渐降低,水分子的扩散系数增大,局部链运动加快,表明氢键能对于树脂性能有重要的影响。
[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，

本文编号：2496012