Preparation Of SEBS Based Flame Retardant Composite And Simulation Of Cable Joint Coat

Since its industrialization in 1970,hydrogenated styrene-butadiene block copolymer（SEBS）has been recognized as a thermoplastic elastomer（TPE）with a wide range of uses.However,due to its easy combustion and great fire hazard,its application scope is greatly limited.In order to improve its safety,it is very important and urgent to treat SEBS with efficient flame retardants.The molding process of nuclear power cable joint coat was simulated with Moldex3D software based on CAE technology,and the molding process was improved according to the simulation results,which has very important practical significance for preparing qualified nuclear power cable joint coat.Based on the above situation,the main research contents of this paper are as follows:O-SEBS/PP/FR composites were prepared by melt extrusion blending method.The effects of the dosage of magnesium hydroxide（MH）,Lonfsafe and the ratio and dosage of aluminum diethylphosphite（ADP）/melamine urate（MCA）on the mechanical properties,flame retardancy and dynamic combustion behavior of the composites were investigated.The results show that with the increase of the dosage of MH and Longsafe,the flame retardant performance of O-SEBS/PP system is improved,and the mechanical properties show a trend of gradual decline.However,when the dosage of MH and Longsafe is the same,it is found that the comprehensive performance of the flame retardant materials with MH is better.When MH dosage was 50wt%,the limited oxygen index（LOI）of the composite was 28%,the vertical combustion grade was UL-94 V-0,the hardness was72±1A,the tensile strength was 5.21±0.1MPa,and the elongation at break was 596±16%.When the ADP/MCA ratio was 1/2 and the dosage was 30wt%,the composite performance was the best,LOI was 29%,31.9%higher than that of pure O-SEBS/PP,hardness was 66±1A,tensile strength was 7.86±0.1 MPa,elongation at break was648±16%.The results of cone calorimetry and thermogravimetric analysis show that the performance of flame retardant materials with MH is better than that with ADP/MCA in dynamic combustion.Co MPared with pure O-SEBS/PP,the peak heat release（PHRR）and peak smoke generation rate（PSPR）of O-SEBS/PP/MH flame retardant materials decreased by 67.2%and 83.1%,respectively.The amount of carbon residue increased from 1.1%to 35.8%of O-SEBS/PP,showing good flame retardancy and smoke inhibition effect.O-SEBS/PPO/FR composites were prepared by melt extrusion blending.The effects of the ratio and dosage of ADP/MCA,aluminum phosphite（AHP）/MCA and the dosage of SEBS-g-MAH on the mechanical properties,flame retardant properties and dynamic combustion behavior of the composites were investigated.The results show that the addition of SEBS-g-MAH improves the co MPatibility of matrix and flame retardant.When the dosage of SEBS-g-MAH is 6,the comprehensive performance is the best.At this time,the flame retardant material LOI is 29%,UL-94reaches V-0 grade,hardness is 69±1A,tensile strength is 6.80±0.1MPa,elongation at break is 525±23%.Under the same dosage and ratio,AHP/MCA has better flame retardant effect and less damage to mechanical properties than ADP/MCA.When the AHP/MCA is 1/2 and the dosage is 30wt%,the LOI of the flame retardant material is30%,UL-94 is V-0,the hardness is 65±1A,the tensile strength is 7.73±0.1MPa and the elongation at break is 606±19%.The results of cone calorimetry and thermogravimetric analysis show that the performance of flame retardant materials with AHP/MCA is better than that with ADP/MCA.Co MPared with O-SEBS/PPO,the PHRR and PSPR of O-SEBS/PPO/AHP/MCA flame retardant materials are reduced by 79.6%and 69.8%respectively.The amount of carbon residue increased from 2.9%to 14.1%of pure O-SEBS/PPO,the ignition time（TTI）increased from 20s to 30s,and the fire performance index（FPI）increased from 0.019 to 0.138.Flame retardant effect is remarkable.Based on Modex3D software,the orthogonal test was carried out on the cable joint jacket for nuclear power.The volume shrinkage rate and the total warpage displacement were taken as the judgment criteria of the orthogonal test,and the range analysis was carried out on both of them,and the optimal results were A₁B₁C₃.This indicates that the appearance quality of the cable connector for nuclear power is the best when the melt temperature is 190℃,the mold temperature is 40℃and the filling time is 1.2s.Co MPared with the initial results before orthogonal test,the volume shrinkage rate decreased from8.490%to 7.395%,the total warping displacement decreased from 0.943mm to 0.814mm,the volume shrinkage rate decreased by 12.9%,and the total warping displacement decreased by 13.7%.