Structure And Performance Of Natural Rubber/Graphene/Carbon Black Composites

Due to the attracting charateristics such as large specific surface area and specialelectronic structure, graphene oxide (GO) and reduced graphene oxide (rGO) have beendemonstrated to endow rubber composites with unusual reinforcement, thermal conductivity,electrical conductivity and so on. In the present study, we used GO or rGO to substitute partof carbon black (CB) in carbon black reinforced natural rubber (NR). The preparation,interfacial structure, mechanical properties, reinforcement mechanism of these natural rubbercomposites were systematically investigated.As GO and rGO tend to aggregate during the melt compounding of rubber, theco-coagulation process has been adopted to make GO or rGO layers dispersed well in NR.The Raman spectra fitting results indicate that GO and rGO are coated on the surface of CB,and the presence of the layers decrease the microcrystallite planar size. TEM observationsconfirm GO and rGO are homogeneously dispersed in NR. And the results of strain sweep onuncured compounds indicate GO and rGO promote the dispersion of CB, and form a muchdeveloped fillers network. Due to weaker interaction between GO and NR, the networkstructure in the NR/GO/CB composites could collapse at smaller strain, comparing to theNR/rGO/CB composites.Analysis on vulcanization characteristics indicate GO delays the vulcanization. Thecross-linking density and the mechanical properties of the NR/GO/CB composite are firstlyincreasing with GO content and then decreasing with GO content. When small amount of GOis used to substitute the carbon black, the100%modulus and tear strength could be doubled.Accelerated vulcanization is achieved by mixing tea polyphenols (TPs) into NR/GO/CBcomposites. At a small content, TPs improve the flex cracking resistance, heat build-upproperty and mechanical properties, especially the100%modulus, which increase with TPscontent. Better thermal aging resistance is achieved when TPs is included. But SEMobservations indicate the incorporation of TPs leads to the formation of some voids inNR/GO/CB vulcanizate.The substitution of CB with rGO leads to remarkably increased mechanical propertiesand fatigue performance of the composites. DMA analysis shows the storage modulus of the composites increases, while tan δ value decreases with the increasing rGO in the composites.The cross-linking density is also higher than that for NR reincorced by CB only. At rGOcontent of1phr, the tensile strength is increased by19.0%. The100%modulus is increased87.0%and the flex cracking resistance is increased by3.4folds when rGO content is3phr.