Study On Processing-structure-properties In Natural Rubber Filled With Carbon Nanotubes

In this paper, the interaction of natural rubber (NR) and carbon nanotubes (CNT),structure of filler-filler network and the synergy of fillers were analyzed by RPA,DMA, SEM and TEM. The processing of HAAKE Rheometer, the effect of sulfur andzinc oxide were also studied.The study of formula shows that the mechanical properties of CNT/NRcomposites are better when using the JIS formula. Through changing the amount ofsulur and zinc oxide, we find that the mechanical properties of CNT/NR are goodwhen the amount of sulfur and zinc oxide is3.5phr and6phr respectively. Theresearch of processing of HAAKE Rheometer is investigated by changing the speed ofrotor, the initial temperature and mixing time. The results show that CNT get gooddispersion with lower initial temperature and lower speed of rotor.The reinforcement of CNT is significant even at small loadings in comparisonwith CB, and their reinforcement is outstanding at low strain. The results of boundrubber analysis, SEM and TEM show that the interaction between NR and CNT isstrong and the CNT disperse well in NR without aggregating. The CNT formthree-dimensional net structure in NR, so that the stress of CNT/NR composites at lowstrain is improved, and a mode is built to explain this phenomenon. When the strain of CNT/NR composites is low, the structure of CNT network in CNT/NR isthree-dimension net and it plays the role of “skeleton” supporting the matrix. Withstrain increasing, the three-dimensional network structure is broken gradually, the roleof “skeleton” becomes ineffective which reduces the reinforcement of mechanicalproperties. When the three-dimensional network structure is broken completely, thestress is supported by the matrix completely.The research of coupling effect shows that the reinforcement of coupling fillers isbetter than single filler. When the amount of CNT and CB is9phr and20phrrespectively, the properties of CNT/CB/NR composites are similar to NR filled with50phr CB. When the amount of CNT and CB is9phr and30phr respectively, the stress,tear strength and hardness of CNT/CB/NR composites are better than NR filled with50phr CB. The network of CB does not form when the amount of CB is10phr and20phr，but the adding of CNT connect the CB grape structure and the network of fillerforms, which provides better reinforcement. Compared with NR filled with30phr CB,the mechanical properties of NR filled with30phr CB and3phr CNT are improvedobviously. And the mechanical properties of NR filled with6phr CNT and30phr CB isequal to NR filled with40phr CB.The study of composites prepared by solution blending method shows that thefiller-filler network starts to form when amount of CNT is3phr，4phr and5phr, andbecomes strong when the amount is8phr and10phr. With the amount of CNTincreasing, the interaction between fillers increases, and the filler-filler network ismore likely to be broken with the strain increasing, the contribution of filler network tostorage modulus increases at the same time. Through thermal process, the storagemodulus of CNT/NR is improved and the Payne effect becomes obviously.