Structural and dynamical heterogeneities of isotactic polypropylene adsorbed onto carbon fiber

Carbon fiber (CF) reinforced polymers (CFRPs) have been widely used in various industries. One of the most important parameters that controls the macroscopic property of CFRPs is the interface between a polymer matrix and CF. There is growing evidence to suggest the formation of a bound polymer layer (BPL), i.e., polymer chains that physically adsorb onto a filler surface. However, this interface is always in contact with the thicker part of a polymer matrix, rendering its understanding a difficult task. Therein, we used CF-reinforced isotactic polypropylene (iPP) as a rational CFRP. To characterize the iPP BPL on the CF surface, we extracted it from the CFRP using solvent-rinsing with p-xylene. The physical and thermal properties of the BPL were characterized by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), while its microscopic structures and dynamics were probed by quasi-elastic neutron scattering (QENS) above the melting temperature. Subsequently, we employed atomistic molecular dynamics (MD) simulations to complement the QENS results and reveal details that were not accessible experimentally. In this talk, we will discuss the flattening process of the backbone and side groups at the interface and resultant heterogeneities in the structures and dynamics of the BPL.