On the Post‐Curing Thermal Treatment of Silicone Rubbers: A Study on Electrical Performance

ABSTRACT Silicone rubbers, particularly poly(dimethylsiloxane) (PDMS), are popular across various industrial applications; however, notable issues arise from volatile cyclic siloxanes and their tendency to compromise performance. This study investigates the electrical performance (DC conductivity, dielectric spectroscopy, DC breakdown) of two commercial PDMS products, before and after a post‐curing treatment (200°C, 4 h). The tested materials, named PDMS A (RTV) and PDMS B (LSR), are chosen as they display distinct characteristics: they differ in terms of outgassing behavior and structural alterations during treatment. In particular, thermogravimetric analysis (TGA) reveals pronounced volatile removal in PDMS B, while Fourier transform infrared (FTIR) and Raman spectroscopy demonstrate pronounced structural alterations in PDMS A (crosslinking of unreacted long chains) promoted by post‐curing. As expected, the electrical insulation performance is enhanced in both post‐cured materials: the magnitude of this enhancement depends on the extent of the two abovementioned aspects. The DC conductivity reduction follows the volatiles removal pattern (larger scale in PDMS B), while the ε′ and ε″ values reduce following the structural alteration pattern (elimination of a relaxation peak in PDMS A). The DC breakdown strength enhancements are driven by structural variations rather than the removal of volatiles.