Preparation Of 125℃ Radiation Cross-linking Halogen-free Flame Retardant Polyolefine Cable Compounds

This work aims at the preparation of 125℃ radiation cross-linking halogen-free flame retardant polyolefine cable compounds. By choosing suitable systems of substrate, flame retardant, antioxidant and sensitizer, the formulation systems for 125℃ radiation cross-linking halogen-free flame retardant LDPE and EVA cable compounds have been established and studied, and the factors of the effect on flame retardant, mechanical and heat resistance properties have been discussed too.The results showed that the system with LDPE as basic material was unsuitable for 125℃ radiation cross-linking halogen-free flame retardant polyolefin cable compounds, but EVA system is successful greatly. The EVA containing high VA has good compatibility with Mg(OH)2, the effect of radiation on the oxygen index of composition depends upon the degree of cross-linking carbonization of basic resin and the destruction degree of flame retardant by radiation, there is synergistic effect between the antioxidant and flame retardant, the radiation increases the tensile strength and decrease the elongation at break. After radiation cross-linking ,the grade of heat resistance of EVA/Mg(OH)2 system is up to 125#.In addition, in this paper silicone resin is used as accessory ingredient for processing in halogen-free flame retardant EVA/Mg(OH)2 formulations which could increase MFR of compound significantly and make the surface of extruded products smooth, and act as a kind of dispersing agent of Mg(OH)2 inEVA. Moreover, silicone resin has synergistic reaction with Mg(OH)2 in formulations which increase 01 and decreases smoking efficiently.Lastly, what is worth mentioning is the use of the cone calorimeter test which played a wonderful role in this work. By the way of the cone calorimeter test, possible fire retardant mechanisms were discussed.