Synthesis of a Novel Siloxane Crosslinker Containing Aromatic Rings and Its Effect on the Heat Resistance of Fluorosilicone Rubber

ABSTRACT Fluorosilicone rubber (FSR), while serving as a fundamental rubber in edge technologies, suffers a serious oxidative aging problem when serving at high temperature. In this paper, a novel FSR crosslinker (named Si‐PH) was successfully synthesized via platinum‐catalyzed hydrosilylation of 1,4‐bis(dimethylsilyl)benzene (BDSB) and 2,4,6,8‐tetramethyl‐2,4,6,8‐tetravinylcyclotetrasiloxane (V 4 ). The chemical structure of Si‐PH was investigated using gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance hydrogen spectra ( 1 H‐NMR). The rheological and thermal properties of Si‐PH were evaluated by rheometer and thermogravimetric analysis (TGA). The results demonstrated that Si‐PH possessed excellent processability (maximum viscosity is 3.2) coupled with robust thermal stability ( T d5 = 332°C). The thermal stability of Si‐PH vulcanized FSR (named P‐FSR) was investigated via TGA, thermal aging test at 250°C for 72 h. The results showed the P‐FSR exhibited superior thermal stability over FSR vulcanized with conventional 2,5‐dimethyl‐2,5‐di(tert‐butyl) peroxyhexane (DBPH) (named D‐FSR). P‐FSR maintained over 75% of its initial tensile strength after aging at 250°C for 72 h, while the tensile performance of D‐FSR was only 53% of its initial tensile strength after aging. This research advances the development of heat‐resistant FSR for critical aerospace, military, and automotive applications—particularly in high‐temperature sealing components including engine O‐rings, gaskets, fuel system seals, and transmission assemblies.