Reinforcement effect of glass fiber modified by tannic acid and polyethyleneimine on polyamide 6 composites with no volatile organic compounds emission

As an important surface modifier, conventional silane coupling agents generally emit volatile organic compounds (VOCs) like methanol or ethanol during the modification of glass fiber. To avoid VOCs emission, a phenol/amine co-deposition of tannic acid (TA) with polyethyleneimine (PEI) was used to modify glass fiber (TP-GF) based on mussel-inspired surface chemistry. The reinforcement effect of TP-GF on polyamide 6 (PA6) matrix was investigated, and the corresponding results were compared with those of γ-aminopropyltriethoxysilane (KH550) modified glass fiber (KH550-GF)/PA6 composites. The results showed that the interfacial adhesion between TP-GF and PA6 matrix was superior to that between KH550-GF and PA6 matrix, and thus TP-GF/PA6 composites manifested more excellent mechanical properties than KH550-GF/PA6 composites. Among these composites, TP-GF (1.05 wt% of coating amount)/PA6 composites exhibited the optimal mechanical properties (tensile strength: 151.3 MPa, notched impact strength: 13.8 kJ m −2 ) compared with KH550-GF (1.33 wt% of coating amount)/PA6 composites (tensile strength: 144.8 MPa, notched impact strength: 9.5 kJ m −2 ). In particular, the notched impact strength was significantly increased by 45%. Notably, there was no VOCs generation during the preparation of TP-GF, indicating that TP-GF could be used as an environmentally friendly glass fiber for the fabrication of high-performance PA6 composites.