Magnesium-PMMA Composites Formed by Mechanical Alloying

The mechanical alloying process is used to form poly methyl methacrylate (PMMA)-5 vol.% magnesium (Mg) composites by high-energy ball milling the blends for up to 10 hours. The milling products and their compacted composites are characterized and compared with milled pure PMMA. Mechanical alloying can cause degradation of the amorphous thermoplastic polymer in the powder mixture but also allows for increasingly fine dispersion of Mg in the PMMA matrix with milling. X-ray diffraction (XRD) and image analysis of optical micrographs show that the magnesium remains crystalline, and its particle size reduces with milling time from an average of 200 microns to under 10 microns after 10 hours milling. Additionally, peak broadening from XRD analysis shows decreasing crystallite size within the particles. The hardness of the composite increases with milling time by up to 7%, whereas the hardness of the milled pure PMMA decreases with milling time by about 5%.