Silicone Grease Absorption Behavior of Silicone Rubber and Evolution of Its Mechanical Properties and Crosslinking Density Under Multiphysics Fields

Silicone rubber (SiR), commonly used in power cable accessories, is usually exposed to the environment of high temperature, mechanical expansion, electric field, and silicone grease swelling. This study investigates the silicone grease absorption characteristics and the evolution of the mechanical properties and cross-link density of silicone rubber under the individual and synergistic effects of above-mentioned multiphysics fields. The influence of DC electric field and tensile strain on silicone grease absorption behavior is first analyzed. The individual and combined effects of temperature, tensile strain, and silicone grease swelling on the elastic modulus, elongation at break, tensile strength, and stress relaxation behavior of silicone rubber are then systematically explored. A second-order generalized Maxwell model is proposed to clarify the mechanisms through which these factors affect stress relaxation. Finally, the impact of these factors on the physical and chemical cross-linking densities of silicone rubber is quantified. Through this multi-stage experimental and modeling approach, this work establishes key correlations between the degradation mechanisms of silicone rubber and the operational stress factors encountered in cable accessory applications.