Preparation And Properties Of Flexible Conductive Silicone Rubber Based On Modified Carbon Black

Flexible conductive materials with carbon-based conductive particles have been widely used in sensors,flexible electrodes,electromagnetic shielding and other fields.Flexible conductive silicone rubber(CSR)stands out among flexible conductive materials due to its excellent mechanical properties and electrical conductivity.However,the flexible CSR filled with carbon-based conductive particles has problems such as agglomeration and uneven dispersion of conductive fillers in the silicone rubber,weak interaction between the conductive fillers and the matrix,which reduces the mechanical properties and the conductive stability of CSR.Therefore,in this paper,different surface modification of carbon black(CB)was firstly carried out to reduce the agglomeration of CB in the matrix,promote its dispersion,and improve the interaction between CB and SR matrix,so as to prepare a good flexible CSR with good mechanical properties,excellent electrical conductivity and electrical stability.In this paper,3-mercaptopropyl-trimethoxysilane(KH-590)was used to graft CB,and then silver particles were reduced on its surface to prepare KH-590 modified CB/silver composite conductive particles(SMCB@Ag).Using the attraction between the sulfhydryl groups of KH-590 and silver ions,the coating amount of silver on the CB surface can be increased to 19%,and SMCB@Ag conductive particles with grape branch-like structure were successfully prepared.The compounding of CB and silver improves the electrical conductivity of CSR,and the electrical conductivity of SMCB@Ag/CSR reaches 7.5 S/m,which is 10 times that of CB/conductive silicone rubber(CB/CSR).The grape branch-like structure restricts the migration of conductive particles in the matrix and improves the conductive stability of CSR.The conductivity of SMCB@Ag/CSR remained above 7 S/m after static storage for 360 h,and the highest conductivity could still reach 5 S/m after 100 strain cycles.However,due to the presence of silver particles in the conductive particles,the mechanical properties of CSR decrease,and the tensile strength decreases from 0.86 MPa(CB/CSR)to 0.42 MPa.Dopamine was in situ polymerized on the surface of CB to prepare composite conductive particles(CB/PDA)that could be cross-linked with the SR matrix.The conductivity of CB/PDA doped CSR can reach up to 15 S/m,which is 20 times higher than that of CB/CSR.Due to the cross-linking reaction between dopamine and the SR matrix,the cross-linked network and conductive network inside the CSR are more stable,and the tensile strength of the CSR is improved,which is about twice that of CB/CSR.After standing for 360 h,the CSR conductivity was almost unchanged.After100 strain cycles,the electrical conductivity can be maintained at a maximum of 13.5S/m.Therefore,the flexible CSR prepared with CB/PDA as the conductive filler has achieved significant improvements in mechanical and electrical properties,as well as conductive stability.