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Liquid polysulfide rubbers (thiocols) are widely used in practice to regulate properties of epoxy com posite materials. It has been established [1][2][3] that, in the case of composites cured without heat input from outside, i.e., when a quite large amount of rubber should be added in order to achieve maximal values of the adhesion strength at room temperature (about 60 wt %/100 wt % of epoxy oligomer), which, consid ering the high cost of thiocol, leads to a quite signifi cant rise in the cost of the material. In addition, with such a large content of the modifier, the cohesive strength, modulus of elasticity, and water and wear resistance significantly decrease in comparison with the basic epoxy polymer.By analogy with liquid oligobutadiene rubbers with end carboxyl groups [4][5][6], it was assumed that this disadvantage can be avoided if there is preliminary carrying out (before introduction of a curing agent) of the interaction reaction of mercaptan groups and oxirane cycles at the elevated temperature and, then, the product of this thioetherification reaction is used as the resin part for curing at room temperature: According to data [3] obtained with the use of dif ferential scanning calorimetry, such interaction occurs in a wide temperature interval of 80-180°C.In the present work, an attempt was made to com paratively investigate the properties of polymers based on epoxy-thiocol composites obtained via simplemechanical mixing of the components at room tem perature or after preliminary thioetherification reac tion (PTER). Epoxy polymers based on epoxy diane resin of Epikote 828 trademark (Hexicon Co.) with 22.8% content of epoxy groups were chosen as the objects of the investigation. The modifier was the liquid thiocol of I trademark with viscosity of 28 Pa s at 25°C and 3.1% content of sulfhydryl groups. The mechanical mixtures were obtained via thorough mixing of epoxy oligomer (EO) with thiocol at 60°C for ~10 min. The products of PTER were obtained via mixing from 30 min to 10 h at temperatures from 90 to 180°C. The compositions were cured in a stoichiometric amount of diethyltriamine DETA at (22 ± 2)°C (cold curing) over 240 h. The samples were thermally treated at 120°C for 3 h.The samples' tensile strength (σ b ) and deformation at break (ε b ) were measured on films (150 μm thick ness) and block samples of standard sizes (according to GOST (State Standard) 11262-80 (type 2)). The modulus of elasticity (E) was calculated by the inclina tion angle of the initial part of the stress-strain curve. A fracture work (A b ) was measured by the area under the σ-ε curve. The ultimate compression strength (σ com ) was determined by GOST (State Standard) 4651-82, the specific impact viscosity (a) by GOST (State Standard) 4647-80, the wear factor (I) by GOST (State Standard) 11012-69, and the adhesive shear strength (τ sh ) by GOST (State Standard) 14759-69.The dynamic mechanical characteristics (dynamic modulus of elasticity (E'), loss modulus (E'') and mechanical loss tangent (tanδ)) were measured on the Abstr...

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