Fracture and adhesion behaviors of epoxy resins modified with poly(amine-quinone)

An amine-quinone monomer, i.e. 2,5-bis(4,4′-methylenedianiline)-1,4-benzoquinone (BB), was synthesize by the Michael addition of 4,4′-diaminodiphenyl methane with 1,4-benzoquinone. To evaluate the effect of BB content on the glass transition temperature (T_g) and crosslinking density (ρ) of cured diglycidyl ether of bisphenol A (DGEBA)/BB systems, storage modulus and loss factor measurements were obtained using dynamic mechanical analysis. The mechanical properties of the systems were determined in terms of the fracture toughness, impact strength, and adhesion strength. As a result, the ρ values of the systems were found to decrease systematically as the BB content increased. The fracture toughness and adhesion strength of the systems increased with increasing BB content. These results indicate that the addition of BB into epoxy resins increases the free volume of the epoxy network and absorbs the deformation energy, resulting in an improvement of the mechanical properties of the DGEBA/BB systems.