Cured Poly(ethylene-g-maleic anhydride)/Graphene Nanocomposite: Properties and Characterization

Poly(ethylene-g-maleic anhydride) (PEMA)/graphene nanoplatelets (xGn) (PEMA-xGn) composites were prepared by melt dispersion in an internal shear mixer. By adding dicumyl peroxide (DCP), cured poly(ethylene-g-maleic anhydride) C-PEMA was also produced. Different amounts of xGn were introduced into the PEMA in range of 0.5–5 wt. %. The effects of the sequence of feeding additives into the mixer on gel content, morphology, and mechanical properties allowed thermal, dynamic mechanical, and rheological behaviors to be studied. Results demonstrated that the incorporation of graphene into the polymer matrix decreased gel content and the rate of crosslinking. Scanning electron microscopy micrographs of the PEMA and C-PEMA nanocomposites showed that below 1 wt. % graphene, its dispersion in the matrix was desirable with no agglomerates.. Crystallization temperature increased due to heterogeneous nucleation by xGn. By curing the nanocomposites with DCP, crystallization temperatures decrease due to crosslinking and decreased crystallinity. The results of crosslinked nanocomposites revealed that, with the exception of C-PEMA containing 0.5 wt. % of xGn, mechanical properties decreased as xGn concentrations increased. Dynamic mechanical analysis showed that the increase of xGn in the PEMA matrix of up to 1 wt. % led to increased storage and loss modulus values. It was also revealed that α-transitions of the PEMA and α- and γ-transitions of C-PEMA were affected by polymer chain branching and graphene nanoplatelets. This could be attributed to interactions and potential bond formations between xGn and the maleic anhydride of PEMA. Rheological properties of the PEMA nanocomposites showed a quick change in the xGn fraction at about 1 wt. %.