Effect of fiber/matrix interfacial adhesion properties on the low-velocity impact resistance of glass fiber reinforced nylon 6 composites

Interfacial adhesion properties are a key factor affecting the mechanical properties of composites. It is a very effective way to improve the low-velocity impact resistance of composites by improving the interfacial adhesion properties. To improve the fiber/matrix interfacial adhesion properties of GF/PA6 (glass-fiber/polyamide 6) composites, polyethyleneimine (PEI) and γ-aminopropyltriethoxysilane (KH550) were used to co-modify GF together in this study. The GF/PA6 composites with different modifications of glass-fiber (GF) were also prepared using a hot pressing process, and then their flexural strength, shear strength, pendulum impact strength, and low-speed impact resistance were investigated. Next, the relationship between fiber/matrix interfacial adhesion and mechanical properties of GF/PA6 composites was investigated by combining x-ray photoelectron spectroscopy, scanning electron microscopy, and x-ray computed tomography test results. The results showed that the GF-reinforced PA6 matrix composite with co-modified GF by PEI and KH550 (PEI-KH550-GF/PA6) had the best mechanical properties, with flexural, shear, and pendulum impact strengths of 660.7 MPa, 53.1 MPa, and 261.6 kJ/m 2 , respectively. Furthermore, the low-velocity impact resistance was measured in terms of stress peak, absorbed energy, residual stress, and damage extension, and the results showed that the low-speed impact resistance of PEI-KH550-GF/PA6 composites was also substantially improved that the F max increased from 7402.1 to 10414.0 N. Highlights Due to the poor surface activity of GF, in this experiment, GF was co-modified with PEI and KH550 to achieve better fiber/matrix interfacial adhesion and successfully improve the mechanical properties of the composites; Different modification methods are used to improve the interfacial adhesion of the fiber/matrix interface. The relationship between the interface and impact strength of composites has been studied; The relationship between fiber/matrix interfacial adhesion and internal cracking in composites was investigated using X-CT and SEM and other test results.