Curing Kinetics Study by FTIR Spectroscopy and Properties Analysis of Methyl Silicone Resin Membrane

Abstract

In order to solve the problem that the curing process of the methyl silicone resin membrane was difficult to control, the curing kinetic was studied. First, the methyl silicone resins with different R/Si values (r) (R, the organic group) were synthesized from methyltriethoxysilane and dimethyldiethoxysilane. The viscosity behaviors of the methyl silicone resin prepolymers were investigated and the viscous flow activation energies were obtained. Then the isothermal curing reactions of the prepolymers were carried out under different temperatures and monitored by the Fourier transform midinfrared (FTIR) spectroscopy synchronously, based on which, the curing reaction rate constants, activation energies and process equations were obtained. After curing processes, the appearances, hardness, tensile shear strength and thermal properties of the methyl silicone resin membranes were also studied. The results showed that the prepolymer with lower r value exhibited greater temperature-sensitive. The isothermal curing process was found to follow third-order reaction, and the optimal curing temperature was 140–150 °C. The film-forming properties of the silicone resins were all good, the hardness and heat resistance increased with the decreased r values. The tensile shear strength on the glass substrate was much better than that of the metal substrates. In conclusion, the optimal curing conditions of the methyl silicone resin membrane were calculated by the FTIR internal standard method, and the performance of the methyl silicone resin membranes produced under the optimal curing conditions were good.