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PROPERTIES OF COMPOSITE MATERIALS BASED ON MIXTURES OF EPOXY POLYMERS AND OLIGOSULFONES. PART 4. ADHESION PROPERTIES

The influence of oligosulfons with terminal carboxyl and phenolic groups and a molecular weight from 1200 to 44500 on the adhesion properties of epoxy polymers during the shift and separation of adhesive compounds is studied. It is shown that modification leads to the formation of systems characterized by improved adhesion properties, especially at elevated test temperatures. It is established that there is an optimal range of concentrations and molecular weights of oligosulfons (approximately from 2000 to 20000), which provides the maximum effect of modification. It is assumed that the oligosulfon`s particles formed in the epoxy matrix with a small molecular weight have dimensions and volume that are insufficient to be an effective barrier to the propagation of a possible crack in the polymer. At the same time, an oligosulfon with a large molecular weight is able to include a certain part of the epoxy resin in its volume. This leads to a relative decrease in the composition of the share of the epoxy component, which largely determines the adhesion to the material to be bonded. It is shown that the magnitude of the modification effect practically does not depend on the nature of the end groups. The maximum set of properties is realized for oligosulfones with terminal carboxyl groups and a molecular weight in the range from 2500 to 4700, when the concentration of 3 – 10 mass parts on 100 mass parts epoxy oligomer. For oligosulfone with terminal carboxyl groups and a molecular weight of 4700 at a concentration of 10 mass parts manages to increase adhesive strength at a shear of 1.47 and 3.58 times and tensile strength of 1.39 and 5.08 times, respectively, at test temperatures of 293 and 423 K. The research results allow to recommend epoxy-oligosulfone mix to design of structural adhesives, operable in a wide temperature range.