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.