The hot compaction process is still the principle method to produce single-polymer composites (SPCs) at present, which limits the industrial mass production of SPCs. In this article, an approach of preparing SPCs by injection molding was demonstrated. Polypropylene (PP) SPCs were prepared at different temperature and pressure. The flexural properties of the PP SPCs were tested. The optimum processing parameters, injection pressure of 140 MPa and nozzle temperature of 220 degrees C were obtained. Flexural strength of the PP SPCs reached up to 43.3 MPa, which is 54.2% higher than that of nonreinforced PP. Flexural strength can be promoted by raising the injection pressure and nozzle temperature. The morphology of the fibers in the PP SPCs was investigated by optical microscope and scanning electron microscopy techniques. The matrix melt was able to penetrate into fiber webs under appropriate temperature and pressure, good interfacial compatibility and bonding properties were obtained. As the injection and holding pressure increased, the penetration capacity could be improved and the arrangement of fibers tended to be closer. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2176-2183, 2013