Investigation of electrical, mechanical and thermal properties of silicone nanocomposites as electrical coating insulation

Silicone rubber (SR) is a high voltage insulation coating, but has poor mechanical properties. Adding nanoparticles is a promising way to deal with this problem. In this study, evaluation of the presence of SiO2, Al2O3, MgO and SiC nanoparticles in the amounts of 0, 2, 4 and 6% by weight in the structure of silicone rubber was done through the distribution of particles within the silicon matrix and simultaneous curing. Mechanical electrical and dynamic-mechanical thermal analysis tests were performed to study the behavior of the prepared samples. Results showed that the presence of nanoparticles even in small amounts increased the strength and elongation at break and the only exception in this regard was the presence of SiC nanoparticles at 4 and 6% by weight in which a decrease in this property was observed. The electrical resistance of SR increased with the mixing of small amounts of nanoparticles. The results of polarization tests showed that the addition of SiC reduced the polarization current to about 200 pA compared to other samples. Dielectric breakdown test showed that the structures containing SiO2 and Al2O3 and 2% SiC nanoparticles had the highest dielectric strength. Dynamic-mechanical thermal analysis tests also showed that the storage modulus and glass transition temperature of the resulting nanocomposites increased up to 7 MPa and about 50 ° C, respectively, The thermogravimetric analysis showed a 100 ° C increase in the degradation temperature and as a result, the thermal stability of the nanocomposites was superior to that of pure silicon.