The impact of matrix viscosity on the mechanical behavior of fiber reinforced composites

Abstract The influence of matrix viscosity on the mechanical behavior of fiber reinforced composites was investigated in this paper. The glass fiber fabric was selected as reinforcement and the mixed solution composed of resin, curing agent and different viscosity of diluent was selected as matrix. The composites was fabricated by vacuum‐assisted resin infusion (VARI). The influence of matrix viscosity on bending, impact and creep properties of composites were studied by varying the mass fraction of 1,4‐butanediol diglycidyl ether (BDDGE) diluent, the least square fitting was used to fit the experimental result. The mathematical model for characterizing the relationship between the matrix viscosity and the bending strength was established, and the mass fraction of BDDGE diluent based on the optimal bending property was obtained. The failure mechanisms were analyzed by analyzing fiber reinforced composites properties, reaction principles and fracture morphologies. Result shows that the epoxy groups within the viscosity undergo a ring‐opening reaction to integrate the cross‐linking network structure of the epoxy resin. However, an excessive amount of diluent will result in an increase of number of flexible chain segments, which initially enhancing the mechanical properties of the specimens before causing a subsequent decline. The mathematical model was substantiated by experiment, which reveals that the viscosity is 185.3 mPa·s for the optimal bending properties. Highlights The bending strength and modulus reached the maximum at a viscosity of 180 mPa·s The creep curves demonstrate progressive damage and minute deformation. The ring‐opening reaction occurs with two oxygen atoms in the diluent BDDGE. The matrix viscosity of BDDGE diluent is 185.3 mPa·s for the optimal bending properties.