【作者】 胡兵；

【导师】 曾黎明；

【作者基本信息】 武汉理工大学 ， 材料学， 2007， 博士

【摘要】 环氧树脂（Epoxy resin，简称EP）由于在强度、模量、热稳定性及耐湿热、耐化学性方面的突出优点而成为应用广泛的基体树脂。但因其固化后交联密度高、质脆等缺点，在很大程度上限制了它在某些高技术领域的应用。因此，对EP增韧研究具有非常重要的理论价值和现实意义。本文在综述了目前国内外环氧树脂增韧方法与机理的基础上，提出了将聚醚醚酮（PEEK）进行化学改性后用于增韧环氧树脂的新思路。主要的研究内容和结论如下：1、以PEEK为原料、浓硫酸为磺化剂，制备了不同磺化度的磺化聚醚醚酮（SPEEK）。研究结果表明，SPEEK的热稳定性好，在400℃以下SPEEK热失重小于3wt％；SPEEK的磺化度随着反应时间和反应温度的增加而提高；与PEEK相比，SPEEK的结晶性下降。SPEEK经过氯甲基化和胺化改性，得到苯环上具有-SO₃H和-CH₂N（CH₃）₂基团的改性PEEK。根据实验数据计算，得到了PEEK磺化反应动力学参数，即表观活化能Ea=35.48kJ／mol，反应速率常数k=2266.5×exp（4267.5／T）。2、利用非等温差示扫描量热法（DSC）分析，确定了改性PEEK／EP树脂体系的固化工艺制度：80℃／2h+125℃／2h+180℃／3h，得到了改性PEEK／EP体系的固化反应表观活化能ΔE=63.82kJ／mol，反应级数n=0.964，固化反应的动力学方程为：dα／dt=1.792×10⁷exp（-7676.2／T）（1-α）^0.964。对改性PEEK／EP体系的固化反应机理进行了初步分析。3、对改性PEEK／EP体系力学性能进行了研究。常温下稳定性好，黏度变化小，凝胶时间较长，在高温下对温度敏感，具有良好的高温反应活性，可以满足施工工艺性要求。改性PEEK在增韧环氧树脂的同时，使固化体系拉伸强度、弯曲强度、弹性模量、断裂伸长率均有不同程度的提高。在实验条件下得到该改性树脂最大拉伸强度、弯曲强度、冲击韧性、断裂伸长率为71MPa、142.3MPa、23.1kJm^-2和4.13％，分别比纯环氧固化物提高了24.6％、53％、151％和56％。当树脂体系中改性PEEK含量为8wt％时，断裂韧性K_IC达到最大值2.169MPa.m^1／2，比纯环氧树脂试样提高了1.1倍。4、DMA测试表明，改性PEEK的加入较好地改善树脂体系的热性能。改性树脂的玻璃化温度Tg、起始分解温度T_onset随着改性PEEK含量的增加而升高，储能模量E′在Tg以下随着改性PEEK的含量的增加而增大。其长期使用温度为186.7℃。5、根据DMA、SEM、FT-IR测试结果，初步提出了PEEK和改性PEEK增韧环氧树脂的增韧机理。以分散相颗粒的桥联和钉锚作用为主导，基体屈服共同作用的增韧机理。由于改性PEEK极性基团进入固化交联网络而成为网络结点，起到了较好的应力分散和承受应力的作用，增韧效果更好。更多还原

【Abstract】 Recently, Epoxy resins （EP） have attracted growing attention because of their outstanding advantages on strength, modulus, thermal stability, and heat, moisture and chemical resistance, making them widely used in many applications as resins matrixs. However, Epoxy resins suffer from their high joint density and brittleness of the cured resins, which limited them applications in many high-tech fields. Thus, it is necessary to investigate the toughening EP for their theoretical and practical researches. In this dissertation, the methods and mechanisms of toughening EP have been reviewed, and a view to toughen epoxy resins by poly（ether ether ketone） （PEEK） which was modified by chemical method had been proposed based on experimental results. Main contents and conclusions of this dissertation are as follows:（1） SPEEK with different degree of sulfonation was synthesized by using sulfonation reactions of PEEK and concentrated sulfuric acid. The results indicated SPEEK exhibit excellent thermal stability, displaying less than 3 wt% weight loss at 400℃. The degree of sulfonation of SPEEK increases with the enhancement of the reaction temperature and time. Compared with PEEK, the crystallinity of SPEEK was identified to decrease. It was found that the modified-PEEK with -SO₃H and -CH₂N（CH₃）₂ groups could be obtained by the chlorinemethylation and the amination modification.According to the experimental data, the dynamics parameters of PEEK sulfonation reaction was calculated. The activation energy of sulfonation reaction Ea was 35.48 kJ/mol, and constant k was 2266.5 exp （4267.5/T）.（2） By using DSC, the processing of the curing for the modified PEEK/EP system was ascertained to be 80℃/2h＋125℃/2h＋180℃/3h. The activation energy E of the solidification reactions of modified-PEEK/EP system is 63.82 kJ/mol, and the order of reaction n and the dynamic equation of the solidification reaction dα/dt are 0.964 and 1.792×10⁷ exp（-7676.2/T ）（ 1-α）^0.964, respectively. Furthermore, the curing reaction mechanism of was the modified PEEK/EP system discussed.（3）The mechanical properties of modified-PEEK/EP system were examined. The modified-PEEK/EP system exhibits superior stability with less change of viscosity and longer gelation time at the room temperature, and sensitive to temperature with better high temperature reaction activity at the high temperature. All these properties of modified-PEEK/EP system can satisfy the requirement of practical applications. The modified-PEEK/EP solidification system displays higher toughness, tensile strength, bending strength, elasticity coefficient and fracture elongation ratio compared wtih EP. The maximum of tensile strength, bending strength, impact intensity and fracture elongation ratio get about 71 MPa, 142.3 MPa, 23.1 kJ/m2 and 4.13%, respectively. Compared with the pure epoxy resin, modified-PEEK/EP system displays superior mechanical properties. The maximum of fracture toughness K_IC is up to 2.169 MPa.m^1/2, which is 2.1 times of pure EP solidification system.（4）The results of DMA analysis indicated that modified PEEK improved the thermal properties of the resin system. The glass transition temperature Tg and the onset temperature T_onset of resin system increased with the enhancement of modified-PEEK content, and storage modulus E’ elevated with the increase of modified PEEK content below Tg. The long-term application temperature of the modified resins was up to 186.7℃.（5） According to the results of DMA, SEM and FT-IR, the toughening mechanism of PEEK and modified-PEEK toughening EP were discussed initially. The toughening of PEEK and modified-PEEK toughening EP rely on the cooperation effect of bridge-link anchor of the dispersed phase, piaying the leading role and the effect of shearing-bending of the matrix in the secondary position. The toughening effect of modified PEEK exhibit more effective, which are ascribed to the contribution of the polar groups of modified-PEEK. Entrance of the polar groups of modified-PEEK into the solidification joint network, becoming the network points, played an important role of dispersing and enduring stress.更多还原