Research On The Methyl Phenyl Silicone Rubber Filled With Carbon Materials

Methyl phenyl silicone rubber(PMPS)was prepared by ring opening copolymerization.Due to the introduction of phenyl,the mechanical properties of silicone rubber,temperature range of high damping,radiation resistance and high temperature resistance performance had been improved.They could be used in the field of manufacturing,such as aviation,sealing,etc.Carbon materials could be divided into graphene,carbon black,carbon nanotubes,etc.They all had unique microstructures.For example graphite had a large conjugated ? bond.It could be filled in two methyl silicone rubber to provide good conductivity.So it had been used in electromagnetic shielding with long life and high temperature resistant.Due to the different molecular structures from PDMS,the interaction between benzene ring from PMPS and graphite,graphene and carbon nanotubes might exist,which gave the material more special properties.By mixing phenyl silicone rubber with flake graphite,expanded graphite(EG),carbon nanotubes and graphene respectively,we explored the relationship between carbon material particle size,microstructure,dosage and the properties of PMPS rubber.Through structure characterization and comparison,we revealed the interaction mechanism between PMPS rubber with different carbon materials.The preparation of conductive silicone rubber with good performance was also included.The EG is firstly mixed with PMPS-3 and PDMS,and then washed off by Soxhlet extractor with toluene as solvent to get EG-1 and EG-2.FT-IR and Raman spectra indicate there were n-n stacking between PMPS-3 and EG?Four kinds of graphite with different diameter are filled with PDMS,PMPS-1,PMPS-2 and PMPS-3respectively.It is found that the mechanical properties of the silicone rubber are reduced more with the increase of graphite particle size.Tensile strength of flake graphite/pmps-3 is the always the strongest one because of the relatively better combination between them.It is found that the optimum content of MWNT in silicone rubber is 2phr.SEM shows that MWNT is well dispersed in the 2phr content.SSNMR and equilibrium swelling method are used to verify the interaction between PMPS-3 and MWNT.The percolation threshold of MWNT is 4phr.The volume resistivity is 9.32×106?·cm,which is reduced by about 7 orders of magnitude compared with that of pure PMPS-3.When the content of GNs is 0-2phr,the tensile properties of the composites increases with the increase of GNs.This effect is most significant in PMPS-3.GNs is well dispersed and closely integrated with the PMPS-3 interface.In addition,the introduction of GNs can improve the damping performance of silicone rubber.And the damping capacity improved the most for PMPS-3.The percolation threshold of GNs is 2phr.The volume resistivity is 8.3×x105?·cm.Which is reduced by about 8 orders of magnitude compared with pure PMPS-3.MWNT/GNs/PMPS-3 is prepared by MWNT,GNs and PMPS-3.To reach the best conductivity ratio,the dosage is 2phr/lphr/100phr.In the meantime,the volume resistivity of the silicone rubber decreases by 9 orders of magnitude compared with the blank sample,while tensile strength,the hardness and crosslinking density increases.SEM shows that MWNT and GNs are uniformly dispersed in the rubber matrix.MWNT is used as the conductive bridge to connect the gap between the GNs layers,which leads to form an effective conductive network.