Tribological and nanomechanical responses of 3D microstructured polypropylene matrix using interpenetrated graphene-carbon nanotubes

This study utilized 1D carbon nanotubes (CNTs) and 2D graphene nanosheets (GNs) in preparation of 3D microstructured polypropylene (PP) nanocomposites with improved anti-wear and nanomechanical responses. The nanocomposites fabricated through melt compounding using Haake Rheomixer showed well dispersed nanoparticles in the matrix due to the aid of PP grafted maleic anhydride (PP-g-MA) coupling agent. The developed PP-CNTs-GNs hybrid nanocomposite showed lower coefficient of friction compared to the pure PP and its nanocomposites containing individual CNTs and GNs. PP-1CNTs-1GNs hybrid nanocomposite had lower wear rate of about 1.01 × 10⁻⁵ mm³/mN compared to 8.9 × 10⁻⁵ mm³/mN, 4.2 × 10⁻⁵ mm³/mN, and 4.8 × 10⁻⁵ mm³/mN measured for the pure PP, PP-3CNTs and PP-3GNs nanocomposites, respectively. The PP-1CNTs-1GNs nanocomposite respectively showed reduction in mass loss of about 78.7%, 62.2%, and 69.1% when related to the pure PP, PP-3CNTs and PP-3GNs nanocomposites. Maximum hardness and elastic modulus of about 153 MPa and 2.7 GPa were measured for PP-3CNTs-1GNs hybrid nanocomposite, while about 86.4 MPa and 1.5 GPa were recorded for the pure PP, respectively. The enhanced properties of the hybrid nanocomposites are due to the good synergetic effect of CNTs-GNs and the formation of 3D microstructures in the PP matrix with relaxed molecular chains and network hardening of the PP matrix.