Halogen-Free Flame Retardant EPDM/EVA Composites

Ethylene propylene diene monomer (EPDM) is an anti-aging and heat-resistant rubber with excellent comprehensive properties. Ethylene-vinyl acetate copolymer (EVA) is a cheap and good processing elastomer with heat-resistance oil resistance and excellent flexibility. Both have a large number of applications in many areas, and very suiTablele for flame-retardant and resistant rubber material formula ablation design requirements. In this paper, formulation of flame retardant and heat resistant EPDM/EVA was designed; effects of additives and process on flame retardant properties of EPDM/EVA were investigated.A variety of flame retardants and other additives have been blended with EPDM/EVA in two rolling open melting machine. Characterization was carried out based on the experimental requirements and properties of treated rubbers were investigated. Experiments include three aspects:First, IFR system on EPDM/EVA modification; Second, surface pretreatment of intumescent flame-retardant; Third, synergy effect between IFR and other flame-retardants in EPDM/EVA. Flame retardancy, heat resistance, mechanical properties and the dispersion of flame retardant in rubber have been investigated by LOI, the vertical burning test, TGA, universal tensile testing machine and SEM respectively. The results show that the optimal ratio of IFR is APP/PER= 3:1, with which the LOI can reach 25.7, vertical combustion can reach FV-1 levels, there is a large decrease of tensile strength. Comparison of four commercial IFR on EPDM/EVA flame retardant modified the results show that AP6000A retardant effect, is the best. By adding 1% silane coupling agent KH-560 pretreatment, mechanical properties can be improved, the tensile strength of Rubber can be increased from 7.37MPa to 8.96MPa, and the tear strength increased from 17.9MPa to 35.1MPa. In order to improve the flame retardancy, synergistic effects between the flame retardants were studied. The results show that a variety of flame retardants have synergistic effect with IFR, and there exists an optimal ratio between each type of flame retardant synergist and IFR. The synergism of encapsulated red phosphorus is the most obvious; adding intumescent flame retardant 30% and red phosphorus 5%, LOI can reach 27.8% and the vertical burning can reach up to FV-0 level, a small amount of red phosphorus has little effect on the mechanical properties of rubber.