Thermal Stability and Properties of Flame Retarded Glass Fiber Reinforced Polyamide 66 Composite

A new flame retardant (FR) was synthesized by using melamine, phosphoric acid and zinc oxide as raw materials. The obtained zinc-ion modified melamine polyphosphate (Zn-MPP) was used as an intumescent flame retardant in glass fiber reinforced polyamide 66 (PA66/GF). The effect of Zn-MPP on flame retardancy, thermal degradation and mechanical properties of intumescent flame retardant reinforced polyamide 66 system (PA66/GF/Zn-MPP) has been investigated. The results demonstrated that Zn-MPP is very effective in flame retardancy of PA66/GF. The limited oxygen index (LOI) value of PA66/GF/Zn-MPP reaches 39.2% when the Zn-MPP loading is 25 wt% in PA66/GF. It was also found that when the Zn-MPP loading is only 22wt% in PA66/GF, the flame retardancy of PA66/GF/FR can still pass V-0 rating, and its LOI value also reaches 37.8%. TGA data obtained in pure nitrogen demonstrated that Zn-MPP has a good ability of char formation itself, and Zn-MPP shows a high initial temperature of the thermal degradation. It was found that Zn-MPP is comparatively stable in the range of processing temperatures of PA66 and is suitable for flame retarding glass fiber reinforced PA66. The PA66/GF/Zn-MPP (22%) has good properties with flame retardancy UL 94V-0 rating (1.6mm), tensile strength 129.4MPa, flexural strength 185.0 MPa, and notched impact strength 7.0 kJ m -2 .