Preparation And Studies On Conductive Silicone Rubber Composites Filled With Conductive Carbon Black

There are mainly three scientific problems in this paper:first, the curing retardtion phenomena was found in the high temperature vulcanized silicone rubber composites filled with super conductive carbon black BP2000(HTV SR/BP2000), the vulcanization retarding mechanism was revealed and the retarding problem was resolved; second, the room temperature vulcanized silicone rubber (RTV SR)/BP2000 system was studied, and vulcanizates with excellent mechanical and electrical properties was obtained together with the vulcanization mechanism; and third, the electrical properties of HTV SR/carbon nanotubes(CNTs) composites was discussed.Conductive CB endows the insulating silicone rubber (SR) with electrical conductivity. It also has a reinforcement effect on the SR at the same time. The reinforcement depends on the type, physical properties, filling volume of CBs, as well as the interaction between matrix and CBs and the curing degree of the vulcanizates. When BP2000, the super conductive CB, filled in HTV SR, the HTV SR/BP2000 composite can not cure completely to get vulcanizates with good physical properties. By comparing with the natural rubber (NR)/BP2000 system, which vulcanized by the peroxide mechanism, HTV SR/BP2000/CTAB system and HTV SR filled with other CBs, it was found out that the functional groups on BP2000 surface plays an important role on the vulcanizing retardation of HTV SR/BP2000. FTIR and XPS analysis on CB surface shows that, there are large amount of oxygen groups on BP2000 surface, especially phenolic-OH. They inhibited the curing reaction in the peroxide curing mechanism of HTV SR/BP2000 by the capturing of initiators of the curing with phenolic-OH, and it was verified by the uncuring of HTV SR/phenol.The excellent electrical and reinfocement of BP2000 worked effectively when it was filled in the room temperature vulcanising silicone rubber(RTV SR), which was vulcanized by the condensation mechanism. A simple procedure for the preparation of RTV SR/CB composite was discussed. It was found that when the dosage of super conductive CB BP2000 was fixed at 20 phr, RTV SR/BP2000 vulcanizate with tensile strength of 10.10MPa, tearing strength of 21.3, elongation at break of 1622.0% and the volume resistivity of Lgpv=0.77 was got. But due to other HTV SR/CBs, the increase in the mechanical properties of the corresponding RTV SR/CBs are not as big as the increase in the electrical properties. The better electrical conductivity shown in RTV SR/CBs can be attributed to the low viscosity and good fluidity of the matrix, it makes CB dispersed meanly. SEM tests verified this suggestion.Besides the cross-linking network in the matrix, the interaction between CB and rubber is the main reason for its reinforcement on polymer. The number of bound rubber is often used to measure the reinforcement of the CB on the matrix. The two-stage swlling test of the vulcanizates with different fillers shows that BP2000 blocks the crosslink reaction. After the H-bond interaction between the matrix and BP2000 was destroied, the average molecule between the crosslink points increased remarkly, especially for the RTV SR/BP2000. This result means that the absorbtion and coating of the RTV SR molecules on BP2000 is the most intense in all of the fillers. The bound rubber measurement and the relative viscosity (RV) testing on the RTV SR/CB blend were carried out, respectively. Compared with the other fillers, the BP2000 enduced the most huge filler-matrix adhesion structure, and the RV of the RTV SR/BP2000 blend grows the most quickly with adding of BP2000. All of the results above revealed that the interaction of the filler-matrix in forms of physical adsorbtion of polymer chains on BP2000 surface was intensely.The reinforcement of BP2000 on RTV SR also reflected when it was filled as the second filler. when the mechanical properties of RTV SR/filler reached its peak, the adding of BP2000 still increased the mechanical properties remarkablely, and the bigger of the difference between BP2000 and the first filler in the physical properties, the more obvious effect of this increasement. Moreover, RTV SR/BP2000 has a low elastic modulus, the stress is only 1.09 when the deformation is 300%, it is a well low modulus material.Due to its extraordinary electrical, thermal, optical, mechanical and chemical properties. Carbon nanotubes (CNTs) have attracted many scientists around the world, and came to be a hot topic in the science area. The preliminary study on the conductive electrical properties of the HTV SR/multi-walled CNTs composite was carried out, together with the resistivity-temperature characteristics analysis of the HTV SR composite filled with different volume of multi-walled CNTs or multi-walled CNTs with surface modification.