Preparation and Properties of Carboxylated Silicone Oils and Their Damping Silicone Rubber Composites

The growing prevalence of vibration and noise pollution in modern industries and cities intensifies the demand for high-performance silicone-based damping materials. However, methyl vinyl silicone rubber exhibits limited damping performance at room temperature. Herein, two kinds of carboxylated silicone oils synthesized via a thiol–ene click reaction between methyl vinyl silicone oil and 3-mercaptopropionic acid were separately added to silicone rubber composites to regulate network structure. The addition of carboxylated silicone oils to silicone rubber composites cured by organic peroxide delays the optimum curing time, reduces cross-link density, introduces hydrogen-bonding interactions and increases energy dissipation, resulting in significant increases in the tan δ value and damping coefficient of the composites at room temperature. The carboxylated silicone oil with higher carboxyl group content further enhances the damping performance of the silicone rubber composites. To compensate for the mechanical deterioration caused by network softening, ethylene-vinyl acetate rubber is further blended with the silicone rubber composites filled with carboxylated silicone oil, which effectively enhances both damping performance and mechanical properties. The combination of carboxylated silicone oil and ethylene-vinyl acetate rubber is an effective strategy for developing silicone rubber composites with good damping performance and mechanical properties for applications in aerospace, transportation, and advanced manufacturing industries.