| In recent years, with the development of nuclear power plant in domestic construction, the demand of cables for nuclear power station is in rapid growth. Nuclear power cable need special requirements such as its radiation resistance and flame retardant due to its application in high radiation, high temperature environment. At present, most nuclear cables ensure the performance by insulation structure design, however its manufacturing technology is complex and process control is difficult. The flame retardant and the irradiation resistance of cable insulation material itself will be the important direction of nuclear cable. Based on this, the flame retardant and irradiation resistance properties of the composite are investigated by mixing EPDM with functional materials in order to lay a solid foundation for the preparation of high performance flameretardant and irradiation resistant cable materials.In this paper, the synthesis process of phenylenediamine cyclotriphosphazene was investigated by comparing water bath method with microwave method. The synthesis process of microwave technology has shorter reaction time and higher production yields than this of water bath method. The optimum process in the microwave heating conditions was that the microwave power was 800 W, reaction time was 10 min, the yield was 58%, but the water bath reaction temperature was 60 ?, heating time was 6 h, yield was 47%.In this paper, the radiation resistant and flame retardant of EPDM composites were systematically investigated. First of all, the effects of aluminum hydroxide (ATH), magnesium hydroxide (MH), zinc borate (ZnB), montmorillonite (MMT), ammonium polyphosphate (APP) and pentaerythritol (PER) on flame retardant properties of the EPDM composite were investigated by the uniform design method. The uniform design data regression analysis results showed that dosages of aluminum hydroxide and magnesium hydroxide (mass ratio 2:1) in composite had the greatest influence on the elongation at break of composite materials, dosages of montmorillonite had the greatest influence on the tensile strength of the composite materials, dosages of ammonium polyphosphate and pentaerythritol (mass ratio 2:1) in composite had the greatest influence on oxygen index of the composites materials, dosages of zinc borate in composite had the greatest influence on the balance torque of the composites materials. When dosages of the ATH and MH, MMT, APP and PER, ZnB were 100 phr,5 phr,6 phr,6 phr respectively, the oxygen index, tensile strength, breaking elongation and balance torque of the EPDM composite were 30%, 5.49 MPa,841.84% and 22.1 N-m respectively.Secondly, effects on the mechanical properties of the composite were investigated. The tensile strength and elongation at break of composite materials could be enhanced by the PP and mPE. When dosages of the EPDM, EVA, PP, mPE were 60 phr,10 phr,15 phr and 15 phr respectively, the tensile strength, breaking elongation of the composite were 10.22 MPa and 834.46% respectively.Finally, effects on the oxygen index, tensile strength, elongation at break and electrical properties of the phenylenediamine cyclotriphosphazene, resistant Fl radiation additives, resistant F2 irradiated additives were investigated by the uniform design method. The regression analysis results showed that, the tensile strength and oxygen index of composite materials increased with the increase of F2 significantly, the volume resistivity of the composites decreased with the increase of F2 significantly. The elongation at break of composite materials increased with the increase of F1 significantly. Effects on the dielectric constant of the phenylenediamine cyclotriphosphazene were not significant before irradiation but significant after irradiation. The breakdown voltage of the materials was influenced by these three irradiation resistant additives insignificant.Eventually, the best formula of the flame and irradiation resistance composite was the EPDM 60 phr, EVA 10 phr, PP 15 phr, mPE 15 phr, APP 4 phr, PER 2 phr, ATH 66.7 phr, MH 33.3 phr, ZnB 6phr, MMT 5phr, phenylenediamine cyclotriphosphazene 2 phr, radiation resistant additives F1 14 phr, radiation resistant additives F24 phr. Then the oxygen index, tensile strength, elongation at break, volume resistivity, and breakdown field strength were 32.3%,11.52 MPa,496.87%, 2.50*1015 ?·m and 14.22 kV/mm respectively. The oxygen index, tensile strength, elongation at break, volume resistivity, and breakdown field strength were 33.5%, 11.25 MPa,422.43%,2.05*1015 ?·m,13.87 kV/mm respectively after the dose of 250 kGy in 10 kGy/h rate irradiation. |
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