Tensile strength rubber nanocomposites

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]. 

In order to understand the relationship between the difference in the interaction parameter of rubber-solvent (Xab) and clay-solvent (xcd) systems and the properties of HNBR/SP nanocomposites, the plots of modulus at 100% elongation and tensile strength versus Xab-Xcd are represented in Fig. 45a, b. An exponential decay in both modulus and tensile strength is observed with the increase in difference of interaction parameter. 7) and 7max follow the same trend as above. 

Mondragon et al. [250] used unmodified and modified natural mbber latex (uNRL and mNRL) to prepare thermoplastic starch/natural rubber/montmorillonite type clay (TPS/NR/Na+-MMT) nanocomposites by twin-screw extrusion. Transmission electron microscopy showed that clay nanoparticles were preferentially intercalated into the mbber phase. Elastic modulus and tensile strength of TPS/NR blends were dramatically improved as a result of mbber modification. Properties of blends were almost unaffected by the dispersion of the clay except for the TPS/ mNR blend loading 2 % MMT. This was attributed to the exfoliation of the MMT. 

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. 

Abraham et al. reported that films of pre-vulcanized NR nanocomposite were fabricated by casting and evaporating a mixture of NR latex and aqueous suspension of cellulose nanofibrils (CNF). By this method, the CNF were evenly distributed in the NR composites. The increase of CNF content in the NR matrix caused the increasing the Young s modulus and tensile strength of materials, but the decreasing characteristic rubber elongation. The enhancements in mechanical and dynamic mechanical properties were attributed to the formation of a Zn ellulose complex and the three dimensional network of the CNF in the NR matrix as a result of the deprotonation of the cellulose. 

Compared to the neat NR and CB/NR composites, the addition of the CNTs brought about remarkable increase in hardness, tensile modulus and tensile strength to the rubber material. The rebound resilience and dynamic compression properties of the CNT/NR nanocomposites are better than that of CB-filled NR composites, which is beneficial for the actual application such as tire, etc., under a dynamic condition. The fracture morphology of the cured CNT/ NR nanocomposites is shown in Figure 6.16. 

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. 

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