Enhancing the thermal stability and mechanical properties of phenyl silicone rubbers by controlling BN addition and phenyl content

Silicone rubber matrix composites with high thermal stability and flexibility are widely used in electronics and aerospace industries. In this work, boron nitride (BN) was added into the phenyl silicone rubber matrix as the reinforcement, and the influence of both the BN content and phenyl content on the thermal stability and mechanical properties of as-prepared composites was studied. The results showed that the thermal stability and mechanical properties were efficiently enhanced by BN addition, regardless of the phenyl content in the matrix. When the filler content was fixed at 40 wt%, the composite with 20 mol% phenyl showed the highest initial decomposition temperature (T5%) of 454 °C and good flexibility (tensile strength, elongation at break and hardness reached 3.10 MPa, 145% and 56 A). However, the decomposition temperature of 30% weight loss, mass retention rate at 800 °C and mechanical properties were improved for the composite with 50 mol% phenyl. The enhancement in thermal stability and mechanical properties was ascribed to the coupled effects of the interfacial force between the matrix and BN particles as well as the pores inside the composite, which was verified by Fourier transform infrared spectroscopy and scanning electron microscopy.