Preparation And Properties Of Dual Network Conductive Rubber Compositrs

Conductive rubber composites are resistant to low temperature,low density,easy to manufacture and have corrosion resistance,it's conductivity is in a wide range of controllable,so it's widely used in aerospace industry,medical,life and other fields.At present,conductive rubber composites need to solve a problem that reducing the amount of conductive fillers while maintaining a high conductivity.It is found that the combination of two or more conductive fillers can produce synergistic effect on the conductivity of the conductive rubber composites,and obtain the composites which is excellent in mechanical and conductivity properties.In this paper,two kinds of conductive fillers are used to study the influence of different filler addition and ratio on the electrical conductivity of the composites.The relationship between the conductive network and the macroscopic conductivity of the composites is studied.First,the expandeded graphite/carbon nanotubes/carboxyl nitrile rubber conductive dual-network composites were prepared by using two kinds of conductive fillers,such as expandeded graphite and carbon nanotubes,based on carboxyl nitrile rubber.The relationship between the conductive network structure of two kinds of conductive fillers of expanded graphite and carbon nanotubes and the electrical conductivity of composite materials was studied.The results showed that:(1)The expandeded graphite was sonicated in aqueous solution of polyvinylpyrrolidone,and under the condition of ultrasonic power of 300W for 0.5h,and then under the condition of ultrasonic power of 1000W for 0.5h,the thickness of the graphite nano-sheets were 5-6nm,the sheets diameter were about 1?m.(2)With the same filler addition,the conductivity of the expandeded graphite and carbon nanotubes composites is closer to the higher conductivity of carbon nanotubes/carboxyl nitrile rubber composites,indicating that the fillers have a synergistic effect on the conductivity of the composites.When the two kinds of conductive fillers were added,the conductivity of the composites increased from 4.08E-11 S/cm to 1.37E-7 S/cm,and the conductivity of the composites increased by four orders of magnitude,indicaing that the composites reaches the conductive seepage threshold.The dual-network structure of the two kinds of fillers was characterized by scanning electron microscopy and transmission electron microscopy.Then carbon black/carbon nanotubes arrays/methyl vinyl silicone rubber dual-network conductive composites were prepared by using carbon black and carbon nanotubes arrays conductive fillers and methyl vinyl silicone rubber.The effects of the amount and ratio of two kinds of conductive fillers on the conductivity and electrical stability of the composites were studied.The results showed that:(1)When the single kind of conductive filler is added,the resistance value of the composite material is higher and the conductivity is poor under the action of stretching.The conductive filler inside the composite material is oriented in the drawing direction,and it is easy to be destroyed,the distance between the conductive particles increases,leading to an increase in the tunnel resistance,so the resistance changes greater with the strain.(2)The use of two kinds of conductive fillers to fabricate composite materials can form conductive dual-network structure.Under the action of tension,the conductive paths is less affected.Therefore,the resistance of the composites changes smaller with the strain and the electrical stability increases.(3)when the carbon black and carbon nanotubes were used in combination,with the amount of carbon black was 1.8 vol%and the amount of carbon nanotubes arrays was 1.2 vol%,the volume resistivity of the composites was 271 ? · cm.