Investigation of the structural and mechanical properties of polypropylene-based carbon fiber nanocomposites by experimental measurement and molecular dynamics simulation

This study investigates the interfacial strengths between polypropylene (PP)/carbon fiber (CF) composites through experimental observation as well as using molecular dynamics (MD) simulation to determine optimal chemical functionalization groups for four PP/CF composites. First, the structures of PP/CF, PP-graft-maleic anhydride (PP-MAH)/CF, PP-MAH/CF-NH₂ (2%) and PP-MAH/CF-NH₂ (5%) were constructed to obtain stable interface structures by the simulated-annealing procedure, and these structures were further used to evaluate the interface bonding strength. The study found that the degrees of crystallinity of PP and PP-MAH at the interfaces are significantly improved when compared to those of the pristine structure. The results show, through the interaction energy per unit area and the tensile simulation mechanical strength, that the strengths of the modified PP/functionalized-CF are higher. Finally, the MD simulation results of the modified PP and functionalized-CF composites are demonstrated to provide an economical and quick approach to examine the mechanical properties of a polymer composite system before conducting an experiment. Such MD results can be utilized to guide both the design of polymer/carbon fiber composites and to select proper functionalized groups.