Synthesis of Organic Modified SiCw/PVDF Composite Membrane and Its Dielectric Properties under Low Temperature

Cetyltrimethylammonium bromide (CTAB) was incorporated into silicon carbide whiskers (SiCw) to improve their hydrophobicity. The solution casting method was employed to develop composite membranes of polyvinylidene fluoride (CTAB-SiCw/PVDF) with different feed ratios. FT-IR spectroscopic studies proved that CTAB was successfully incorporated into the SiCw. SiCw phase structure was maintained after modification by CTAB according to XRD results. SEM studies indicated that the surface became smoother with CTAB dispersal in the PVDF membrane. The dielectric properties of the composite membranes containing various amounts of CTAB-SiCw were measured at low temperature. It was found that the dielectric constant of the composite membranes with 13.0wt% whiskers reached a maximum value of 25 at low frequency, and decreased to nine at high frequency (from 500 Hz to 1 MHz ) at 0 celcius. The dielectric loss of each composite membrane increased with increasing temperature and reached a maximum value. The value shifted with corresponding frequency increases. In addition, the dielectric loss reached a maximum value of 0.2 when 16.7wt% of CTAB-SiCw was fed at each frequency (from -30 celcius to 10 celcius). At room temperature, the dielectric constant could be maintained at 42 and the loss factor decreased to 0.8 at 100 Hz when 13.0wt% of CTABSiC(w) was incorporated. Additionally, TGA experiments indicated that the decomposition temperature of a PVDF membrane was increased by 10 celcius and its heat resistance was improved by adding 13.0wt% of CTAB-SiCw. This PVDF composite membrane has potential for use as an insulator and capacitor.