This paper investigated the reinforcing effects of a hybrid filler, including talc and exfoliated graphene
nanoplatelets (xGnPs), in polypropylene (PP) composites. In order to increase the interphase adhesion,
maleic anhydride grafted polypropylene (MAPP) was added as a compatibilizing agent to the PP/talc/
xGnP composites. The experiments were designed according to response surface methodology (RSM) to
optimize the effects of three variable parameters, namely talc, MAPP and xGnP, on the mechanical
properties. In the sample preparation, three levels of filler loading were used for talc (0, 15, 30 wt%), xGnP
(0, 0.75, 1.5 wt%) and MAPP (0, 2, 4 wt%). From the analysis of variance (ANOVA), it was found that the
talc and xGnP play a significant role in the mechanical properties and morphology of the composites, as
proven by scanning electron microscopy (SEM) and differential scanning calorimeter (DSC). In order to
simultaneously maximize these mechanical properties, the desirable values of the additives were predicted
to be 30 wt% for talc, 4 wt% for MAPP and 0.69 wt% for xGnP. The obtained normal probability
plots indicated good agreement between the experimental results and those predicted by the RSM
models.