Study On Toughened And Reinforced Nylon66 With Non-halogen Flame-retardants

Glass fiber reinforced nylon 66(GFPA66) has excellent strength, but its flame retardant property can not meet the requirements of household appliances, because the "wick" effect of glass fiber makes GFPA66 easier to burn and can not achieve the flame retardant requirements.Yet there is no effective way to improve the flame retardancy of PA66 without loss of its physical properties.A halogen-free flame retardant nylon 66 system was presented in this paper that short glass fiber as reinforcing agent, encapsulated red phosphorus powder and micron-level magnesium hydroxide as flame retardant, orthogonal test and comparison test were used to determine the best formula of better flame retardant properties and mechanical properties. The performance of flame retardant system and the mechanism of each component were studied by thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Specific contents and conclusions were as follows:Red phosphorus/magnesium hydroxide co-efficient had the excellent effect to GFPA66, 25 copies of the GF,10 copies of the RP,16 copies of the Mg (OH)2 and 100 copies of the PA66 can form a halogen-free flame retardant system with better performance. The oxygen index was increased by 50% than pure PA66, flame retardant level reached V-0 class; initial decomposition temperature was reduced by 63℃, amount of residual carbon was increased by 13%; the largest crystallization temperature was raised by 26.1℃, the relative crystallinity was improved by 6.6%; tensile strength was 27.6MPa more than pure PA66, 9.2MPa more than 25 copies glass fiber reinforced PA66; but the impact strength was degraded by 37%; MFR was decreased to 18.7g/10min, the flow properties of PA66 was improved and extrusion processability is also good.As the impact strength of flame retardant system was decreased sharply, so toughening was necessary, POE-g-MAH had a better improving effect on system's performance than EPDM-g-MAH, although the toughening effect of POE-g-MAH was weaker, but it had less influence to tensile properties and flame retardant properties. Dosage of 5 copies of POE-g-MAH could achieve the best effect, the impact strength of system was raised to 10.62KJ/m2, tensile strength was improved to 92.6MPa, residual carbon at 800℃was decreased by 3%, oxygen index was reduced only 0.6.Surface modification of Mg(OH)2 can improve the mechanical properties and flame retardancy of the flame retardant system, Mg (OH)2 treated with silane coupling agent KH-550 had better mechanical properties and better compatibility with matrix resin, Mg(OH)2 treated with titanate coupling agent NDZ-201 had phosphorus-containing groups, which caused better flame-retardant effect, but the amount of coupling agents can not be too much. Combine these two factors, we use 1.5% of KH-550 to modify Mg (OH)2.In conclusion, a best formula of processing GFPA66 with good performance was obtained and the product had achieved home appliance industry standard.