Enhancement of the mechanical properties of basalt fiber-reinforced polyamide 6,6 composites by improving interfacial bonding strength through plasma-polymerization

This study aimed to develop basalt fiber (BF)/polyamide (PA) 6,6 thermoplastic composites with high strength and light-weight, by employing BF as an environmentally friendly reinforcing material and applying plasma polymerization for improving the interfacial bonding strength between BF and PA6,6. 3-aminopropyltriethoxysilane (APTES) was used as a precursor for BF surface modification. Plasma polymerization of the APTES was applied to the BF surface for 3, 5, 7, and 9 min. The reaction mechanism during plasma polymerization was investigated and compared to that from a conventional solution dipping method. We examined the changes in chemical composition of the BF surface and the resulting interfacial bonding strength and mechanical properties of the BF/PA6,6 composites. The results showed that APTES plasma-polymerized BF formed a strong interface with PA6,6, demonstrating a 50.3% increase in interfacial shear strength and a 32.5% increase in tensile strength compared with untreated BF. Furthermore, APTES plasma-polymerized BF showed excellent results, with 25.7% higher interfacial shear strength as well as 15.1% higher tensile strength compared to the solution dipping results. This is because plasma polymerization formed a thick polymeric layer highly compatible with PA6,6 on the BF surface, and imparted excellent physical and chemical bonding to the PA6,6 matrix.