Preparation of exfoliated graphite nanoplates/thermoplastic polyurethane composites with enhanced dielectric properties

In this work, exfoliated graphite nanoplates (xGNPs)/thermoplastic polyurethane (TPU) composites with enhanced dielectric constant and relatively low dielectric loss factor were prepared by an effective method involving solution blending and water precipitating. The wide-angle X-ray diffraction results proved that the xGNPs had been added into the TPU. Furthermore, the microstructure of the resultant xGNPs (2 wt.%)/TPU composite was investigated by scanning electron microscopy (SEM). The SEM images showed that there were many xGNPs in the TPU elastomer matrix. According to differential scanning calorimetry the melting peak temperature and the crystallization peak temperature of the xGNPs/TPU composites were lower than those of the pure TPU but the melting enthalpy and the crystallization enthalpy of the xGNPs/TPU composites were higher than those of the pure TPU. More importantly, the dielectric constant at 1000 Hz and the thermal conductivity of the xGNPs/TPU composites obviously increased in comparison with those of the pure TPU, especially when the xGNPs content was 2 wt.%.