The effect of processing variables on microstructure of injection molded short fiber reinforced polypropylene composites

Injection molded composites of polypropylene reinforced with short glass fibers were obtained under a variety of injection molding conditions. The microstructure of the moldings was determined using a variety of experimental techniques, including optical and scanning electron microscopy, differential scanning calorimetry, Fourier transform infra‐red spectroscopy, and thermogravimetry. Thus, it was possible to obtain a detailed characterization of the crystallinity, morphology, and orientation distribution in the matrix, in addition to the distribution of fibers and their orientation of the fibers in the composite. The influence of molding conditions on the above microstructural characteristics is summarized in an effort to explain the experimental observations.