POLYPROPYLENE LOW-DENSITY POLYETHYLENE BLEND MATRICES AND SHORT GLASS-FIBER BASED COMPOSITES .3. MORPHOLOGY AND FIBER ORIENTATION

The morphology of short glass fiber reinforced composites based on polypropylene/low density polyethylene (PP/LDPE) blend matrices was investigated by means of an optical microscope as a function of both matrix composition and fiber content. The influence of compounding and processing methods was also studied. The LDPE content hardly affects the morphology of the blends, at least within the range of percentages that have been investigated (5 and 10% by weight). On the other hand, glass fibers obstruct the matrix spherulitic development. The blend morphology is strongly affected by the processing method and the compression molded blends show large spherulitic size than the injection molded ones. Scanning electron microscopy showed the fiber orientation across the injection molded composites.