Tensile modulus rubber-clay 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]. 

Values of Example were calculated for the constituting domains of SEBS (PS and PEB) and for the nanoclay regions in the SEBS/clay nanocomposite using (6) and are provided in Table 2. The modulus of the clay platelets was found to be 100 MPa, whereas the modulus for PS and PEB blocks was determined to be 22 and 12 MPa, respectively. These modulus values tallied with the slow strain-rate macromechanical tensile data of 26 MPa for the SEBS/clay nanocomposite (Table 2). The lower calculated modulus values of nanoclays compared to the literature might be due to adhering soft rubber on the nanoclays, which reduces the overall modulus of clay regions in the composite. 

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. 

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