Performance, Industrialization And Application Of Advanced Rubber/Layered Silicate Nanocomposites

In recent years, rubber/layered silicate nanocomposites have attracted great interest, both in industry and in academia. Compared with conventional composites, they often exhibit remarkable improvement in materials properties. Preparation of exfoliated rubber/layered silicate nanocomposite is a difficult and important task for researchers. The aim of theoretical research is to better serve as practical application, and the industrialization and application of rubber/layered silicate nanocomposite is of importance and practical significance.Latex compounding method is one of the most important methods for preparing rubber/layered silicate nanocomposites, and it is promising for industrialization due to the simplicity of preparation process and superior cost/performance ratio. The latex compounding method is carried on in this paper. Based on this method, exfoliated butadiene-styrene-vinyl pyridine rubber/clay nanocomposite is successfully prepared, and the rubber/layered silicate nanocomposites applied in inner tube of tire, heat-resistant conveyor belt and off the road tire are systematically researched.Firstly, a kind of exfoliated rubber/layered silicate nanocomposite is prepared and the structure is proved by XRD and TEM, in which clay is dispersed in butadiene-styrene-vinyl pyridine rubber by the latex compounding method with the assistance of acidized pyridine group. Dynamic mechanical thermal analysis suggests a strong interfacial interaction between the layered silicates and macromolecules in addition to the weak inorganic-organic interfacial interaction, and solid state 15N NMR indicats the formation of a strong ionic interface through the acidized pyridine group. The exfoliated rubber/layered silicate nanocomposite exhibits a remarkable improvement on the dispersing morphology, mechanical performance, dynamic mechanical property, and gas barrier property, compared to the conventional separated rubber/layered silicate nanocomposite.Secondly, for the purpose of improving the processability of SBR/layered silicate nanocomposites applied in inner tube materials, the related performance of NR/SBR/rectorite nanocomposites, glycerin modified SBR/rectorite nanocomposites, SBR/reclaimed rubber/rectorite nanocomposites and surfur modified SBR/clay nanocomposites are investigated. (1) The increase of NR could improve the processability of the nanocomposites but reduce the gas barrier property. (2) The research of glycerin modified SBR/rectorite nanocomposites shows that, the introduction of glycerin into the nanocomposites could improve the proccessability, enhance the mechanical property and shorten the curing time, at the same time the gas barrier property is maintained. Moreover, FTIR spectrum proves the interaction between glycerin and rectorite layer, and RPA strain sweep of nanocompounds confirms the effect of glycerin on weakening the filler-filler interaction in SBR/rectorite nanocomposites. (3) The incorporation of reclaimed rubber could improve the proccessability and gas barrier property of the nanocomposites, but the effect on the mechanical performance is disadvantageous to its use in inner tube materials. (4) The surfur modification technique could improve the gas tightness and reduce the dynamic heat build-up of SBR/clay nanocomposites, which provides a new idea to enhance the gas barrier property of the rubber composites.Thirdly, the combination effects of nano-clay and nano carbon black on the properties of SBR composites are investigated. The results show that two fillers are uniformly dispersed in the SBR matrix at nano-scale, and the carbon black particles filled into the space between the clay layers. At the same total filling, the clay layers could provide the nanocomposites excellent thermal aging resistance and heat resistance, and the carbon black could reduce the stress concentration generating from the non-homogeneous distribution of clay layers at micro-scale. FTIR and DSC results indicate the differences between the inner layer and the outer layer of the aged SBR/clay/CB nanocomposites, and the heat resistant mechanism is proposed:the incorporation of the layered silicate could hinder the rubber from generating oxygen-containing groups in its surface during high temperature aging, and then the glass transition temperature of the rubber outer layer is lowered down, which keep the rubber macromolecular chains flexible, so as to improve the heat resistant property of the nanocomposites.Then, the small amount of clay as a form of NR/clay nanocompound is introduced into the tread of off the road tire to partly replace carbon black, due to the incorporation of small amount of clay, the mechanical performance, wear resistance property, dynamic heat build-up, cut and chip resistance, crack growth resistance and flex fatigue property are improved in various degrees.Finally, the structure and properties of industrialized product SBR/clay nanocomposites are studied. XRD and TEM show that, the effect of shearing during mixing process could make the dispersed clay layers re-aggregate together increasingly likely, and then decrease the mechanical performance and gas barrier property. The addition of silane coupling agent Si69 into SBR/clay nanocompounds during mixing process could weaken the filler-filler interaction, reduce the viscosity and improve the proccessability, meanwhile, the mechanical performance and dynamic property could be alse raised due to the coupling reaction of silane coupling agent between clay layers and rubber chains.