有机修饰剂对柔性环氧树脂/黏土纳米复合材料热/力学性能的影响

Effect of Type of Organic Modifier on Thermal/Mechanical Properties of Flexible Epoxy/Clay Nanocomposites

分别选用十六烷基三甲基溴化铵(CTAB)、氯化胆碱(CC)及2,3-环氧丙基三甲基氯化铵(GMAC)为有机修饰剂制备了3种不同性质的有机化黏土(CTAB-clay、CC-clay及GMAC-clay)。通过"黏土淤浆复合法"合成了3种具有不同界面强度的柔性环氧树脂/黏土纳米复合材料。采用X射线衍射、透射电子显微镜、拉伸性能测试及动态力学热分析等方法对所制备的纳米复合材料结构及性能进行了表征。结果显示,CTAB-clay形成了插层结构的纳米复合材料;而CC-clay及GMAC-clay得到了剥离/插层混合结构。环氧树脂/黏土纳米复合材料的力学性能随界面强度的增强而增加:3种有机化黏土使环氧树脂的拉伸强度分别提高了333%(3.5%GMAC-clay)、195%(3%CC-clay)、100%(3.5%CTAB-clay);环氧树脂的模量及断裂伸长率亦随有机黏土的加入而同时获得显著提高。CTAB-clay导致环氧树脂的玻璃化转变温度(T_g)有所降低;而GMAC-clay和CC-clay则使T_g略有升高。

Three different types of organic surfactants, cetyltrimethylammonium bromide(CTAB), choline chloride(CC)and 2,3-epoxypropyltrimonium chloride (GMAC) were employed for modification of Na+-montmorillonite clays. Flexible epoxy-clay nanocomposites with different interfacial strength were synthesized using the above organoclays through “slurry-compounding technique”. The effects of the type of organic modifiers on the microstructure and thermal/mechanical properties of flexible epoxy-clay nanocomposites were investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), tensile test and dynamic mechanical analysis (DMA). It is shown that CTAB-clay can only form an intercalated structure;while CC-clay and GMAC-clay give partly exfoliated and partly intercalated structures. It is found that mechanical properties of epoxy-clay nanocomposites depend not only on the degree of exfoliation/intercalation of epoxy/clay nanocomposites but also on the interfacial strength between the epoxy matrix and the organoclay. The tensile strength of CTAB-clay modified nanocomposites is increased by only 100% at 3.5% clay loading;while that of CC-clay and GMAC-clay nanocomposites is enhanced by 195%, 333% respectively. The elongation at break and modulus of the epoxy nanocomposites are simultaneously improved notably. CTAB-clays result in a mildly reduction of Tg of epoxy nanocomposites compared to the pristine epoxy polymer, while CC-clay and GMAC-clay cause a slight increase in Tg of the nanocomposites.