How are the thermal properties of polypropylene/graphene nanoplatelet composites affected by polymer chain configuration and size of nanofiller?

The leading purpose of this work was to broaden the current knowledge about the impacts of various chain configurations of polypropylene (PP), i.e., linear and branched form, on the thermal properties (thermal stability, thermal conductivity, crystallinity, thermal mechanical properties) of PP nanocomposites reinforced by graphene nanoplatelet (GnP) particles. The utilization of GnP with different particle size gave us good information about the impacts of filler's dimension on the thermal properties as well. Regardless of the PP type, EC1500-filled (small size GnP) composites showed higher storage modulus in the dynamic mechanical analysis. With respect to DSC results, incorporation of GnP, particularly GnP with smaller particles, led to a striking increment in crystallization temperature and crystallinity, and nucleating efficiency of GnP in linear PP-based composites was higher. The employment of GnP brought about an improvement in degradation temperature and thermal stability of nanocomposites, and smaller GnP was more effective in this context. However, due to its higher aspect ratio, EC100 GnP (large size GnP) could enhance thermal conductivity more satisfactory, specifically in linear PP-based samples. [Display omitted] •Polypropylene(PP)/graphene nanoplatelet (GnP) nanocomposites were prepared via solid state mixing followed by melt blending.•Small GnP had better performance in dynamic modulus, while large GnP was more effective in thermal conductivity enhancement.•Long side chains in branched PP affected the formation of GnP network and thermal properties, adversely.