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The physical-mechanical properties of epoxy matrices modified with polyethersulfone (PES) and unidirectional glass- and carbon-fiber-reinforced plastics (GFRP and CFRP) based on them were investigated. The fracture toughness of epoxy matrices modified with 20 wt% PES, increased by 4.3 times. The delamination energy of GFRP and CFRP with this content of PES in the matrix increases by 50 and 65%, respectively. A correlation between the fracture toughness of modified matrices and the delamination toughness of GFRP and CFRP was established, and the influence of structure of the matrices on the fracture toughness of the reinforced plastics was demonstrated. A significant increase in the fracture toughness of the matrices and reinforced plastics was also observed during the formation of extended phases enriched with PES. [ABSTRACT FROM AUTHOR]

The application ability of oligomeric copolyimides (OCPI) as epoxy resin modifiers of fiber-reinforced composites was investigated. For this purpose, the properties of epoxy resin compositions based on an ED-20 epoxy resin and iso-MTHPA modified by oligomeric copolyimides with terminal anhydride groups were studied. It is shown that the incorporation of OCPI into the ED-20 epoxy resin does not reduce the manufacturability of the initial binder (the viscosity of all binders is almost similar in composite formation conditions), increases the "binder-fiber" interface strength (the growth in the adhesive strength reaches 40%) and can slightly improve or reduce the heat capacity (the alteration in the glass-temperature is ± 16-22°C). The magnitude of the effects obtained depends on the amount of injected oligoimide amount and its structure. An analysis of the results obtained allows us to suggest that the reactive oligomers can serve as modifiers of the epoxydiane resin in the production of fiber-reinforced structural plastics. [ABSTRACT FROM AUTHOR]