Improved Interlaminar Properties of Glass Fiber/Epoxy Laminates by the Synergic Modification of Soft and Rigid Particles

Poor interlaminar fracture toughness has been a major issue in glass fiber-reinforced epoxy resin (GF/EP) laminate composites. In this paper, soft carboxy-terminated nitrile (CTBN) rubber particles and rigid nano-SiO2 are used to toughen the epoxy resin (EP) matrix to improve the interlayer properties of GF/EP laminate composites. The effects of adding two toughening agents on the mechanical and interlayer properties of GF/EP laminates were studied. The results showed that adding the two kinds of particles improved the mechanical properties of the epoxy matrix. When the additional amount of flexible CTBN rubber particles was 8 wt%, and the rigid nano-SiO2 was 0.5 wt%, the fracture toughness of the matrix resin was increased by 215.8%, and the tensile strength was only decreased by 2.3% compared with the pure epoxy resin. On this basis, the effects of two kinds of particles on the interlayer properties of GF/EP composites were studied. Compared with the unmodified GF/EP laminates, the interlayer shear strength and mode I interlayer fracture toughness is significantly improved by a toughening agent, and the energy release rate G(IC )of interlayer shear strength and interlayer fracture toughness is increased by 109.2%, and 86.8%, respectively. The flexible CTBN rubber particles and rigid nano-SiO2 improve the interfacial adhesion between GF and EP. The cavitation of the two particles and the plastic deformation of the matrix is the toughening mechanism of the interlayer properties of the composite. Such excellent interlaminar mechanical properties make it possible for GF/EP laminates to be widely used as engineering materials in various industries (e.g., aerospace, hydrogen energy, marine).