Study On Conductive Silicone Rubber Materials

In this paper,the preparation method,conductivity and morphology of conductive silicone rubber were studied,and the conductive mechanism of conductive silicone rubber was explored.Silicone rubber with different conductivity was prepared by using three metal composite conductive fillers?silver-coated aluminium powder,silver-coated glass beads,nickel-coated graphite?and two carbon-based conductive fillers?carbon nanotubes and graphene?.The effects of five kinds of fillers and different types of fillers on the mechanical properties,electrical conductivity,processability and morphology of conductive silicone rubber were studied.In the first part of the thesis,five kinds of conductive fillers were separately added into silicone rubber to prepare conductive silicone rubber.The effect of the amount of conductive filler on the performance of conductive silicone rubber was studied.The results showed that the percolation threshold of conductive silicon rubber with silver-plated aluminum powder was about 210phr with the volume resistivity 1×10^-3?·cm and the surface resistance 0.017?.The percolation threshold of silver-plated glass beads conductive silicone rubber was about 250phr with the volume resistivity 6.77×10^-3?·cm and the surface resistance 0.26?.The nickel-plated graphite conductive silicone rubber had a percolation threshold of about 160phr with the volume resistivity 1.96?·cm and the surface resistance 22.82?.The percolation threshold of the carbon nanotube conductive silicone rubber was about 7phr.At this time,the volume resistivity was11.89?·cm and the surface resistance was 66.53?.The percolation threshold of graphene conductive silicone rubber was about 25phr.At this time,the volume resistivity was 3250?·cm,and the surface resistance was 5200?.The volume resistivity and surface resistance of the five conductive silicone rubbers decreased by about 10 orders of magnitude near the percolation threshold,and the conductivity was greatly improved.Scanning electron microscopy?SEM?tests showed that five conductive fillers were evenly dispersed in the conductive silicone rubber in the morphological structure without significant agglomeration.With the increase of conductive filler addition,the five conductive silicone rubber filler networks became more and more structural,and the filler network was formed preferentially over the conductive network.The five conductive fillers all reduced the mechanical properties of the conductive silicone rubber.In order to reduce the amount of metal fillers and build a new conductive network in the silicone rubber matrix,six kinds of conductive silicone rubber with metal composite conductive fillers and carbon conductive fillers were prepared in the second part of the paper.The effects of different types of fillers and their amount on the properties of conductive silicone rubber were studied.The results showed that the percolation threshold of silver-plated aluminum powder/carbon nanotube conductive silicone rubber was about 130phr/2phr,and the percolation threshold of silver-plated glass beads/carbon nanotube conductive silicone rubber was about 80phr/3phr.The percolation threshold of nickel-plated graphite/carbon nanotubes conductive silicone rubber was about 100phr/5phr,the percolation threshold of silver-plated aluminum powder/graphene conductive silicone rubber was about 100phr/8phr,and the percolation threshold of silver-plated glass beads/graphene conductive silicone rubber was about80phr/5phr.The permeation threshold of nickel graphite/graphene conductive silicone rubber was about 100 phr/5phr.The addition of a small amount of carbon nanotubes and graphene greatly reduced the amount of percolation transition of the metal composite conductive filler,but the conductivity property near the percolation threshold was slightly worse than the use of the metal composite conductive filler.Based on the first two parts,the paper discussed the conductive networks of different types of fillers.The results showed that three-dimensional conductive network composed of different types of fillers in different directions in three dimensions was more stable than the single-filled conductive network,which improved the conductivity.The linear calculation method of metal composite conductive filler and carbon nanotubes was preliminarily fitted.