Solid residue formation of RTV silicone rubber due to dry-band arcing and thermal decomposition

In this study, the solid residue of a RTVSR (room temperature vulcanized silicone rubber) prepared in a tracking test are analyzed. By using the techniques of KBr pellet FTIR (Fourier transformed infra-red) spectroscopy and XRD (X-ray diffractometry), cristobalite SiO₂, amorphous SiO₂, amorphous SiO₂.xH ₂O (namely, silica gel) and moissanite SiC are identified in the solid residue. The TG (thermogravimetry) and TG-DTA (differential thermal analysis) are applied to study the thermal characteristics of RTVSR and the concentration of carbon which contributes to tracking of polymers is evaluated. By comparison of the solid residue of the tracking test to thermally decomposed RTVSR in air and nitrogen, models of chemical changes during the formation of the solid residue are proposed. Furthermore, it is found that RTVSR has a excellent property not to form conductive carbon