Rubber nanocomposites properties

Effects of Fillers on Rheological Properties of Rubber and Rubber Nanocomposites.785... 

EFFECTS OF FILLERS ON RHEOLOGICAL PROPERTIES OF RUBBER AND RUBBER NANOCOMPOSITES... 

Maiti et al. [14] have studied the effects of different nanoclays (namely, NA, 10A, 20A, and 30B) on the properties of BIMS rubber. They have characterized the clays and the rubber nanocomposites by means of FTIR, , and XRD. 

The X-ray diffraction peaks observed in the range of 3°-10° for the modified clays disappear in the rubber nanocomposites. photographs show predominantly exfoliation of the clays in the range of 12 4 nm in the BIMS. Consequently, excellent improvement in mechanical properties like tensile strength, elongation at break, and modulus is observed by the incorporation of the nanoclays in the BIMS. Maiti and Bhowmick have also studied the effect of solution concentration (5, 10, 15, 20, and 25 wt%) on the properties of fluorocarbon clay nanocomposites [64]. They noticed that optimum properties are achieved at 20 wt% solution. At the optimized solution concentration, they also prepared rubber/clay nanocomposites by a solution mixing process using fluoroelastomer and different nanoclays (namely NA, 10A, 20A, and 30B) and the effect of these nanoclays on the mechanical properties of the nanocomposites has been reported, as shown in Table 4 [93]. 

Du et al. (50) reported the synthesis of butadiene styrene rubber nanocomposites with halloysite nanotubes. The tensile properties of the composites containing various amounts of nanotubes are depicted in Table 2.2. The tensile properties were observed to significantly increase as a function of increasing amount of nanotubes in the composites. For the maximum loading of the nanotubes, a tensile modulus of 5.56 MPa was observed as compared to 1.52 MPa for the pure polymer. 

Table 2.2. Mechanical properties of butadiene styrene rubber nanocomposites with halloysite nanotubes...

The barrier properties of starch nanocrystals/natural rubber nanocomposites were also investigated [39]. For these systems, the water vapour transmission rate, the diffusion coefficient of oxygen, the permeability coefficient of oxygen and its solubility, were measured. It was observed that the permeabiUty to water vapour, as well as to oxygen, decreased when starch nanocrystals wctc added These effects were ascribed to the platelet-like morphology of the nanocrystals. 

Bandyopadhyay, A., Maiti, M., and Bhowmick, A. K. 2006. Synthesis, characterisation and properties of clay and silica based rubber nanocomposites. Journal of Materials Science and Technology 22 818-828. 

Molesa et al. [61] compared compounded styrene-butadiene nanocomposites with polymer nanocomposites that were prepared by blending the latex with an aqueous dispersion of the montmoriUonite. The loading of the dispersed phase was at 10 phr. The initial results are consistent with the information found above. The flocculated rubber nanocomposite from the aqueous blend has superior strength properties when vulcanized and compared with the rubber nanocomposite prepared by compounding. MontmoriUonite that was organically treated demonstrated superior tensile strength when compared with rubber compounded with sUica. 

Zhang et al. [63] prepared styrene-butadiene nanocomposites by dispersing an aqueous dispersion of montmoril-lonite and latex and flocculating the dispersion with acid. The performance of the rubber nanocomposites were compared with clay, carbon black, and silica rubber composites prepared by standard compotmding methods. The montmoriUonite loadings for the rubber nanocomposite were up to 60 phr. The morphology of the rubber nanocomposites by transmission electron microscopy appears to indicate intercalated structures. The mechanical properties of the rubber nanocomposites were superior to all of the other additives up to about 30 phr. However, rebound resistance was inferior to all of the additives except sUica. The state of cure was not evaluated. 

R. Stephen and S. Thomas, in Rubber Nanocomposites Preparation, Properties and Applications, ed. S. Thomas and R. Stephen, John Wiley Sons, Chichester, 2009, Chapter 2, pp. 1-12. 

The mechanical properties of the control NR composite, untreated HNT-filled NR nanocomposite, treated HNT-filled NR nanocomposite, and silica-filled NR composite are tabulated in Table 19.6. The addition of 10 phr HNT loading increased the tensile modulus and tensile strength compared to the neat NR vulcanizate. However, the values of elongation at break of the HNT filled rubber nanocomposite were decreased in comparison to the unfilled NR vulcanizate. The silica filled NR vulcanizate showed inferior properties as comparison to HNT filled nanocomposites. It is well known that the modulus of rubber vulcanizates is proportional to the degree of crosslink density. Therefore, modulus of rubber vulcanizates increased with the increased of crosslink density. In contrast, the elongation at break decreased with increasing crosslink density. 

As reported in Section 23.3, research on rubber nanocomposites has remarkably increased over the last decades, both in the academic and industrial worlds. Nanofillers bring about appreciable improvements of the following properties of a rubber matrix mechanical, rheological, barrier, thermal, degradation, flame resistance. 

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