A novel phosphorous-containing polymeric compatibilizer: Effective reinforcement and flame retardancy in glass fiber reinforced polyamide 6 composites

Glass fiber (GF) can be deemed as a double-edged sword, which improves the strength of polymers but impairs the flame retardant efficiency and toughness. Herein, a novel phosphorus-containing polymeric compatibilizer (PPC) with multiple anhydride reaction sites was synthesized from radical copolymerization. PPC was directly compounded with 3-aminopropyltriethoxysilane modified GF, polyamide 6 (PA6) to prepare fire retarded glass fiber reinforced polyamide 6 (GFPA6) containing aluminium diethlyphosphinate. The multiple anhydride groups on PPC chain can react simultaneously with the amino groups on modified GF and the terminal amino groups on PA6 chain during processing. The modified GF and PA6 matrix are linked in this way, thereby enhancing the interface adhesion between GF and PA6 matrix. The addition of PPC can effectively heighten the tensile, flexural and Izod notched impact strength of GFPA6 composites. When GFPA6 burns, the addition of PPC leads to more continuous and dense carbonaceous char on GF surface, which weakens the “wick effect” and improves the flame retardant efficiency. This work also opens the door for new generations of inorganic reinforced polyamide, polyester and polyurethane.