Effect Of Carbon Materials On Physical Properties Of Composites

Carbon materials as a conductive material is widely used in all kinds of conductive composites.In previous research,the filling quantity of carbon fillers was large,which had a great change on the performance of matrix.Therefore,how to guarantee the conductive composites to achieve the required conductivity,and reduce the amount of conductive fillers was an important issue in conductive composites.In this paper,Carbon black(referred to CB)and Carbon nanotubes(referred to CNTs)as two kinds of conductive fillers were used to prepare the modified carbon/carbon fiber double-layer spacer fabric(referred to CFDSF)/AG-80 composites.And carried out the related research of electrical,mechanical and thermal properties.This paper studied the CB modification way and its content on the performance of the modified CB/CFDSF/AG-80 composites.The research results showed that under the same conditions,the electrical,mechanical and thermal properties of silane coupling agent modified CB(Si-CB)/CFDSF/AG-80 systems were superior to oxide modified CB(O-CB)/CFDSF/AG-80 systems.And The largest difference of electrical performance could reach20.72%,the maximum difference of mechanical properties was up to 14.01%,the biggest difference of thermal performance could reach 17.27%.With the increased of modified CB content,the volume resistivity of two systems could gradually decline,it dropped obviously when percolation threshold was reached.And as the temperature increased,the volume resistivity of two systems would also reduce,which was the NTC effect.In addition,this study also found that the mechanical properties of two systems would decrease then increase with the increased of modified CB content.That was because the surface activity of the modified CB could be large,which was easy to produce stress concentration effect and reduce the mechanical properties.However,with the increased of the content of modified CB,the aggregation structure of CB always produced excellent reinforcing effect,so the mechanical properties increased.Finally,with the content of modified CB increased,the decomposition temperature of two systems gradually increased,which confirmed that the heat resistance of the composites was improved.This paper also studied the different modification way of CNTs and its content on the performance of modified CNTs/CFDSF/AG-80 composites.The research results showed that under the same content,the electrical,mechanical and thermal properties of silane coupling agent modified CNTs(Si-CNTs)/CFDSF/AG-80 systems were better to theacidification of modified CNTs(O-CNTs)/CFDSF/AG-80 systems.And The maximum difference of electrical performance could reach 14.45%,the biggest difference of mechanical properties was up to 5.85%,the largest difference of thermal performance was up to 5.73%.With the increased of modified CNTs content,the two systems showed a decrease in volume resistivity,which dropped obviously when percolation threshold was reached,and they had NTC effect.In addition,it was found that the mechanical properties of two systems increased then decreased with the increased of the content of modified CNTs.This was attributed to the toughening effect of CNTs on matrix,so the mechanical properties increased.With the increased of CNTs content,CNTs tended to reunion and distribution uneven,so the mechanical performance decreased.Finally,the author of this research discovered that the thermal stability of two systems was well and the decomposition temperature was on the raise.It was confirmed that the addition of CNTs could improve the heat resistance of the composites.Comprehensive,the coupling agent modification way of CB and CNTs were both better than oxygen(acid)modified way on each performance of the systems.Si-CNTs/CFDSF/AG-80 systems were different from Si-CB/CFDSF/AG-80 systems on the mechanical properties,and other properties were similar.While the content of Si-CNTs was much less than that of Si-CB when the required conductivity was reached,and the mechanical and thermal properties of Si-CNTs systems were better.