INFLUENCE OF DILUENTS AND PLASTICIZERS ON THE PROPERTIES OF EPOXY-POLYSULFIDE COMPOSITES

It was found that to increase the adhesive and physicomechanical properties of compositions based on epoxy resin and polysulfide rubber (thiokol), cured without heat treatment, it is necessary to carry out a preliminary thioetherification reaction (PRTE) due to the interaction of rubber mercaptan groups and oxirane cycles of epoxy resin at elevated temperatures and then use the product of this reaction to cure at room temperature. Composite materials based on the products of the thioetherification reaction significantly surpass analogs based on mechanical mixtures of epoxy resin and thiokol in terms of cohesive and adhesive strength, deformation capacity, fracture work, and specific impact strength. It is shown that the introduction of both diluents and plasticizers into the products of the preliminary thioetherification reaction of epoxy resins and polysulfide rubbers leads to an increase in the parameters of tensile strength and deformation capacity. The greatest strengthening effect is achieved with the use of oligoesteracrylate MGF-9 and glycidyl ether of diethylene glycol DEG-1, the smallest - with the introduction of the plasticizer EDOS. It was found that the introduction of plasticizers promotes some increase in the adhesive strength, but much less in comparison with the cohesive strength. In this case, the adhesion and cohesive characteristics change antibatically. It has been shown by dynamic mechanical spectrometry that the presence of diluents and plasticizers in epoxy-polysulfide composites leads to a decrease in the temperatures of the maximum values of the tangent of the angle of mechanical losses, loss modulus, the initial and final sections of the transition of the material from the glassy to the highly elastic state, as well as the density of the chemical network in the epoxy matrix.