Modification of microspheres and matrix to improve mechanical properties, thermal stability, and viscosity of thermal insulation composites

In this study, hollow SiO₂ microspheres (HSM) and hollow glass microspheres (HGM) were chemically modified with hexamethyldisilazane (HMDS) to enhance their compatibility with the SR matrix. Additionally, the matrix viscosity was reduced by blending DY-401-100 vinyl silicone oil (DY-401-100 VSO) with hydrogen-containing silicone oil (HSO) and SR. The effectiveness of these modifications was characterized using Fourier transform infrared spectroscopy (FTIR), optical contact angle measurements, and scanning electron microscopy. The surface modification with HMDS improved the compatibility between HSM/HGM and SR, resulting in a 50% increase in the tensile strength of the thermal insulation composite, from an initial value of 1.003 MPa. Concurrently, the matrix modification led to a 66.5% reduction in the viscosity of the SR matrix, and elevated the thermal decomposition temperature of the thermal insulation composite from 427 to 530 °C. These findings demonstrate that HMDS and DY-401-100 VSO/HSO have great potential in enhancing the properties of SR-based thermal insulation composites.