Development of an Epoxy-Polyester Matrix with Improved Adhesive and Physicomechanical Properties with the Use of Isocyanate Modifier

We study the adhesive and physicomechanical properties of composite materials based on the epoxypolyester binders with additions of a methylenediphenyl diisocyanate modifier. It is shown that the matrix with a content of modifier q = 0.25 wt.% is characterized by the highest adhesion and cohesion parameters. The tensile adhesive strength of the epoxy-polyester matrix with improved adhesive properties constitutes sigma(a) = 55 MPa, and its residual stresses are sigma(r) = 4.1 MPa. The matrix with improved cohesive properties is characterized by the following parameters: its modulus of elasticity in bending E = 3.7 GPa, the fracture stress in bending sigma(st) = 57 MPa, and the impact toughness W ' = 8.9 kJ/m(2). The fracture surfaces of composite materials are studied by the method of optical microscopy. It is shown that the presence of modifier strongly affects adhesive and cohesive properties of the investigated materials.