Nanocomposites modulus

Block and clay regions of SEBS nanocomposite Modulus from Hertz model ( Sample) MPa Localized sample deformation (d), nm Modulus from JKR model ( Sample) MP Bulk modulus3 of SEBS/clay nanocomposite, MPa... 

Nanocomposites Modulus at 100% elongation, MPa Tensile strength, MPa Tear strength, kN/m2 Elongation at break, % Hardness, Shore A... 

Figure 14.8. The effect of dispersion on the nanocomposites modulus and strength.

The largest effect of increasing nanocomposite modulus is observed in the broad temperature region of PHEMA glass transition, when the ratio reaches 3. The... 

The data provided by Toyota Research Group of Japan on polyamide-MMT nanocomposites indicate tensile strength improvements of approximately 40%-50% at 23°C and modulus improvement of about 70% at the same temperature. Heat distortion temperature has been shown to increase from 65°C for the unmodified polyamide to 152°C for the nanoclay-modified material, all the above having been achieved with just a 5% loading of MMT clay. Similar mechanical property improvements were presented for polymethyl methacrylate-clay hybrids [27]. 

This is the most widely used naturally occurring rubber. The literature search shows that many research groups have prepared nanocomposites based on this rubber [29-32]. Varghese and Karger-Kocsis have prepared natural rubber (NR)-based nanocomposites by melt-intercalation method, which is very useful for practical application. In their study, they have found increase in stiffness, elongation, mechanical strength, and storage modulus. Various minerals like MMT, bentonite, and hectorite have been used. 

ENGAGE is an ethylene-octene copolymer. Ray and Bhowmick [70] have prepared nanocomposites based on this copolymer. In this study, the nanoclay was modified in situ by polymerization of acrylate monomer inside the gallery gap of nanoclay. ENGAGE was then intercalated inside the increased gallery gap of the modified nanoclay. The nanocomposites prepared by this method have improved mechanical properties compared to that of the conventional counterparts. Preparation and properties of organically modified nanoclay and its nanocomposites with ethylene-octene copolymer were reported by Maiti et al. [71]. Excellent improvement in mechanical properties and storage modulus was noticed by the workers. The results were explained with the help of morphology, dispersion of the nanofiller, and its interaction with the mbber. 

Adsorption of rubber over the nanosilica particles alters the viscoelastic responses. Analysis of dynamic mechanical properties therefore provides a direct clue of the mbber-silica interaction. Figure 3.22 shows the variation in storage modulus (log scale) and tan 8 against temperature for ACM-silica, ENR-silica, and in situ acrylic copolymer and terpolymer-silica hybrid nanocomposites. 

FIGURE 3.23 Plots of storage modulus against variable strain for the cross-linked mbber-silica hybrid nanocomposites (a) (ACM)-silica and (b) epoxidized natural mbber (ENR)-silica at different tetraethoxysilane (TEOS) concentrations. (Erom Bandyopadhyay, A., De Sarkar, M., and Bhowmick, A.K., J. Polym. Set, PartB Polym. Phys., 43, 2399, 2005. Courtesy of Wiley InterScience.)... 

Dynamic mechanical properties of the nanocomposites are shown in Figure 4.6. There is 10% improvement of the storage modulus at 20°C by incorporating only 4 wt% of the nanombe. 

FIGURE 4.6 Variation of storage modulus against temperature for ethylene-vinyl acetate (EVA) nanocomposites having different loadings of carbon nanotube (CNT) and ANT. (From George, J.J., Sengupta, R., and Bhowmick, A.K., J. Nanosci. Nanotechnol., 8, 1, 2007. Courtesy of American Scientific Publishers.)... 

FIGURE 28.16 Storage modulus vs temperature of organoclay-loaded rubber nanocomposite. (From Teh, P.L. et al., J. Appl. Polym. Sci., 100, 1083, 2006.)... 

Researchers [37] also compared the storage modulus of a 40 phr carbon black-filled compound and a 10 phr SWNT-NR nanocomposite. The different properties between carbon black- and SWNTs-filled NR nanocomposites can be explained in terms of two different filler morphology, particularly surface area, aspect ratio, and stmcture. It can be observed from Figure 28.22 that... 

FIG. 9 Dependence of tensile strength and modulus on clay loading for epoxy-CH3(CH2)i7NH -montmorillonite nanocomposites. (From Ref. 35.)... 

Polyimide-clay nanocomposites constitute another example of the synthesis of nanocomposite from polymer solution [70-76]. Polyimide-clay nanocomposite films were produced via polymerization of 4,4 -diaminodiphenyl ether and pyromellitic dianhydride in dimethylacetamide (DMAC) solvent, followed by mixing of the poly(amic acid) solution with organoclay dispersed in DMAC. Synthetic mica and MMT produced primarily exfoliated nanocomposites, while saponite and hectorite led to only monolayer intercalation in the clay galleries [71]. Dramatic improvements in barrier properties, thermal stability, and modulus were observed for these nanocomposites. Polyimide-clay nanocomposites containing only a small fraction of clay exhibited a several-fold reduction in the... 

Poly(styrene-fc-butadiene) copolymer-clay nanocomposites were prepared from dioctadecyldimethyl ammonium-exchanged MMT via direct melt intercalation [91]. While the identical mixing of copolymer with pristine montmorillonite showed no intercalation, the organoclay expanded from 41 to 46 A, indicating a monolayer intercalation. The nanocomposites showed an increase in storage modulus with increasing loading. In addition, the Tg for the polystyrene block domain increased with clay content, whereas the polybutadiene block Tg remained nearly constant. 

Fig. 9.9 Reduced frequency dependence of storage modulus, loss modulus and complex viscosity of neat PLA and various nanocomposites (PLANCs). Reprinted from [40], 2003, Elsevier Science.

Figure 9.28 shows the relation of the relative modulus (Ktf Kp) to the relative density (Pf/Pp) of neat PLA and PLA-based nanocomposite foams, taken in the directions parallel (A) and perpendicular (B) to the flow. 

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