Effects of synergism and multistep heating in graphene–polypyrrole–polymethyl methacrylate composites on their electrical and mechanical properties in additive manufacturing

A highly electrically conductive hybrid multicomponent graphene–polymer composite was produced by solvent casting method with subsequent melt blending processes. As per the experimental design, the composite had to undergo multiple heating steps from solvent casting to extrusion to 3D-printing, the effects of processing conditions, mainly temperature, on its mechanical and electrical properties and the mechanisms behind the changes had to be understood. It has been noted that there is a significant increase in mechanical properties from extruded strand (tensile strength [48 MPa] and flexural strength [27 MPa]) to 3D-printed samples (tensile strength [67 MPa] and flexural strength [61 MPa]). An electrical conductivity of 11.4 S cm⁻¹ was measured for the as-synthesised composite before melt processing. However, the conductivity does not change noticeably until 3D-printing. From the thermogravimetric analysis, it is clear that there is no change in the functionalities of extruded strands and 3D-printed sample, but energy dispersive spectroscopy analysis showed that there is a significant reduction in agglomerates that played a critical factor in improving the homogeneity of the dispersion.