Influence of the Composition of Fluororubbers on the Properties of Their Vulcanizates.

The molecular polarizability and dipole moments of the fragments of copolymer fluoroelastomers was evaluated by the quantum chemical method. It was shown that the polarity of fluororubbers is provided by the presence of vinylidene fluoride units. The dynamic mechanical analysis method was used to obtain the frequency and temperature dependencies of the storage modulus E′ and the mechanical loss tangent tan δ of fluororubbers and vulcanizates on their basis. The characteristic features of the influence of the rubbers composition and vulcanization on the mechanical and thermophysical characteristics of elastomers were established. The values of tensile strength and elongation at break were obtained for vulcanizates of the studied fluoroelastomers, as well as the Mooney viscosity and the compression set values. The crucial influence of the rubber polarity and the vulcanization network parameters on the specified parameters was identified. The swelling kinetics of rubbers and vulcanizates on their basis in 1,2-dichloroethane at 50°С was studied. The sorption limitation degree of the solvent at the appearance of the vulcanization network and its parameters were evaluated. It was found that with regard to the reduction in their equilibrium degree and swelling rate in dichloroethane, elastomers go in the following order: SKF-26 > Elaftor 3061R > Elaftor 7075 > Elaftor 1000R, symbatically to the decrease in their polarity. [ABSTRACT FROM AUTHOR]