thermal and dielectric properties of nano aluminium nitride based silicone nanocomposites

The study describes the use of nano aluminum nitride in developing thermally conductive but electrically insulative flexible materials for use in high-voltage insulation. The study begins with the detailed protocol for hydrophobic surface treatment of nanofillers for enhanced interaction with base silicone gum. TEM and XRD analysis are used to understand the shape, dimensions, and phase of the filler. XRD analysis revealed the coexistence of aluminum oxide in traces along with aluminum nitride. Successful surface functionalization was confirmed through FTIR analysis. No change in XRD patterns after surface modification confirmed the presence of an amorphous functionalized layer. The nanocomposite preparation procedure is described in detail. SEM analysis of nanocomposites revealed a moderate degree of dispersion with localized pockets of agglomeration. DSC analysis is performed to gain insight into the effects of nano aluminum nitride on glass transition, melting, and crystallization temperatures. An interesting pattern in the increase of glass transition temperatures with nanofiller loading levels observed is discussed drawing attention to the aggregated filler effect and the disentangling of silicone chains with increasing interfacial interaction. TGA analysis revealed an early onset of degradation due to the inclusion of high thermally conductive fillers. Dielectric breakdown strength is performed at various nanofiller loadings, with the maximum value obtained at a 2 phr weight loading level. Frequency domain spectroscopy in the range of 1 mHz to 1 KHz was studied under different thermal points.  The increase in complex permittivity at low frequencies due to interfacial polarization is studied in detail. The results are presented and discussed here.