Effect of Nano-silicon Nitride on the Mechanical and Electric Properties of Polypropylene Nanocomposite

Abstract

The nanocomposites of polypropylene (PP) and nano-silicon nitride (chemical formula: Si3N4) were prepared by a twin-screw extruder with isoactic PP granules, within which a proportion of PP granules were coated by nano-Si3N4 modified with a silane coupling agent. The data of mechanical experiments showed that the impact strength of PP nanocomposite materials was improved markedly with up to 25% increasing magnitude while the tensile strength was decreased slightly with less than 10% decreasing magnitude as the content of Si3N4 increased within the PP matrix. Electrical properties of PP nanocomposites showed that the average breakdown field strength of the nanocomposite PP materials was increased by 40% and 10% under AC and DC, respectively, compared to those of neat PP. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) spectra showed that the existence of nano-Si3N4 within the PP matrix made the crystal phase of PP change to some extent due to the interaction of nano-Si3N4 with PP matrix. It was found that the nano-Si3N4 that possessed good dispersion into and chemical physical interaction with the PP matrix had a significant influence on the mechanical and electric properties of nanocomposite Polypropylene.