Effects of -CH₂CH₂CF₃ on properties of RTV polysiloxane rubber: Processability, thermal stability, and oil/solvent resistance

Room temperature vulcanizing fluorosilicone rubbers (FSRs) were prepared from polydimethylsiloxane (PDMS), vinyl fluorosilicone-oil (VFS-oil), and precipitated silica (PDMS/VFS/SiO₂). Rheological tests showed appropriate processing condition could be obtained when shear rate > 10 s^-1. Mechanical tests indicated that tensile strength and elongation at break were not much affected by VFS-oil and no decline was observed after being aged in 70 °C ASTM 1# oil. The -CF₃ group could not only increase oil-resistance, but also decrease surface energy, which were proved by ATR-FTIR and contact angle tests. The PDMS oil immersion tests showed that the higher the content of VFS-oil, the better oil resistance can be obtained. The solvent-resistance tests indicated that the VFS-oil improved resistance to nonpolar/low-polar solvent. TGA results showed that the increasing content of VFS-oil could slightly decrease FSRs' thermal stability but increase FSRs' residual mass ratio at 790°C.