Effect of chemically modified graphene oxide on the phase separation behaviour and properties of an epoxy/polyetherimide binary system

In this study, methylenedianiline-modified graphene oxide (GO-MDA) was incorporated into the diglycidyl ether of a bisphenol A/polyetherimide (DGEBA/PEI) binary system to regulate the Cure-Reaction Induced Phase Separation (CRIPS) behaviour. After the cure-reaction was completed, the fractured surfaces of DGEBA/PEI/GO-MDA composites were etched and observed by SEM measurement to determine the final morphology. Rheological and DSC measurements were used to analyze the effect of GO-MDA on the CRIPS behaviour of the composites. It was found that the CRIPS behaviour of the DGEBA/PEI system, with or without GO-MDA, all followed a spinodal decomposition mechanism. The introduction of GO-MDA increased the complex viscosity and cure-reaction rate of the DGEBA/PEI/GO-MDA composites, which significantly suppressed the development of phase separation and helped freeze the final morphology of the composites at an earlier stage of co-continuous structure. The toughness and modulus of the composites were improved by adding GO-MDA according to DMA measurement and tensile tests, while TGA results showed little decrease in the thermal stability of the composites.