Effect of composite coating on interfacial properties of glass fiber reinforced polyamide 6 composites

In order to obtain the excellent interfacial properties of glass fiber reinforced polyamide 6 (GF/PA6) composite, the glass fiber reinforced polyamide 6 composite was prepared by the composite coating containing polydopamine (PDA) and hexagonal boron nitride (h-BN). The crystal structure, chemical structure, surface morphology and roughness of glass fiber were characterized by XRD, XPS, SEM and contact angle measurement. The effects of the addition of h-BN on the mechanical properties, thermal stability, dynamic thermal mechanical properties and crystallization properties of the composites were investigated. The results show that the surface of the modified glass fiber is covered by the uniform composite coating, which significantly increases the surface roughness, surface activity and chemical bond energy of the glass fiber, and greatly improves the interfacial meshing between the glass fiber and the polyamide 6 resin matrix. The addition of composite coating can induce the transformation of PA6 crystal form from γ crystal to α crystal form. When the content of h-BN is 0.75%, the mechanical properties of the composites are the highest. The tensile strength is 129.8 MPa, which is 79.2% higher than that before modification, and the bending strength is 194.8 MPa, which is 32.2% higher than that before modification. The energy storage modulus reaches 1742 MPa, which increases by 69.9% compared with that before modification.