多壁碳纳米管对环氧树脂/聚醚酰亚胺体系相分离的影响

通过溶液混合的方法制备了环氧树脂/聚醚酰亚胺(PEI)/多壁碳纳米管(MWCNTs)三元复合物,并使用扫描电镜(SEM)、原位红外分析(FTIR)、流变测试和非等温DSC等手段研究了MWCNTs的存在对体系相分离形貌和固化反应的影响.扫描电镜的结果显示,在固化后的样品中MWCNTs较均匀地分散在两相中.150℃下固化,不含MWCNTs和MWCNTs含量为0.75 pbw的体系相分离形貌呈海岛状结构,而进一步增大MWCNTs含量后相分离形貌呈双连续结构,且相区尺寸随MWCNTs含量的增加而减小.120℃下固化,不含MWCNTs和MWCNTs含量为0.75 pbw的体系相分离形貌呈双连续结构,而进一步增大MWCNTs含量后,体系相分离形貌呈相反转结构.FTIR和DSC的测试结果表明,MWCNTs表面的羟基对环氧树脂的固化反应起到催化作用,使得固化反应速度加快,反应活化能降低.而流变测试的结果表明,随着MWCNTs含量增加,一方面交叉跨越多个相区的碳纳米管使得体系黏度增大,对相分离起到了一定的抑制作用;另一方面使得体系凝胶化时间提前,导致体系相分离形貌被固定在相分离的较早阶段,起到有效调控相分离形貌的作用.

EFFECTS OF MWCNTs ON PHASE SEPARATION IN EPOXY RESIN/PEI BLEND SYSTEMS

Epoxy resin/PEI/MWCNTs composites were prepared by solution blending,and the effects of MWCNTs with hydroxyl group on the phase separation of the systems were investigated by scanning electron microscope(SEM),infra-red spectrum(IR),rheological measurements and differential scanning calorimetry(DSC).The SEM results showed that the MWCNTs were uniformly dispersed in both phases of the composite after curing.The phase separation morphology of epoxy resin/PEI blends without MWCNTs or containing 0.75 pbw MWCNTs showed an island-sea structure,and the blend containing more MWCNTs presented a bicontinuous structure when the blends were cured at 150℃.And when the blends were cured at 120℃,the phase separation morphology of the blends without MWCNTs or containing 0.75 pbw MWCNTs showed a bicontinuous structure and the blend containing more MWCNTs presented a phase inversion structure.The IR and DSC data showed that the rate of curing reaction was accelerated and the activity energy of the curing reaction was decreased by introducing MWCNTs into the system due to the existence of the hydroxyl group on their surface.In addition,the results of rheological measurements revealed the fact that,for one hand,the MWCNTs which crossed both phases increased the viscosity of the system,causing an inhibiting effcet on phase separation;for another hand,the gelation time of the composites decreased as the MWCNTs content increased,which indicated that the addition of MWCNTs to the blend restricted the phase separation and morphology evolution in the earlier stage of phase separation,implying that the introduction of MWCNTs with hydroxyl groups into the system was a feasible method to achieve the goal of phase morphology control.