Molecular-scale deformation of glass-fiber-reinforced polypropylene probed by rheo-optical Fourier transform infrared imaging combined with a two-trace two-dimensional correlation technique

Abstract

The molecular-scale deformation behavior of glass-fiber-reinforced polypropylene was probed by a newly developed rheo-optical Fourier transform infrared (FTIR) imaging technique combined with two-trace two-dimensional correlation mapping. This technique, based on an in situ polarized FTIR microscopic analysis, revealed variations in the polymer orientation during tensile deformation. The analyses of composites containing single fibers aligned parallel and perpendicular to the elongation direction clearly revealed that the addition of maleic anhydride-grafted polypropylene (MAPP) restricts the polymer mobility at the matrix–fiber interface and inhibits interfacial debonding during the elongation process. Namely, matrix–fiber adhesion was improved by the compatibilizing effects of MAPP, which in turn contributed to enhanced mechanical properties resulting from the efficient stress transfer and reduction in fracture formation at the matrix–fiber interface. This study demonstrates that the rheo-optical technique can provide a better understanding of the reinforcement mechanism of glass-fiber-reinforced thermoplastics related to interfacial states.