Clays epoxy/clay nanocomposites

Epoxy-clay nanocomposites from epoxide precursors have been investigated by research groups at Michigan State University [34-40], Cornell University [41], and Case Western Reserve University [42,43]. In general, the synthesis is similar to that of Nylon-6 and PS... 

FIG. 10 Compressive (a) yield strength and (b) moduli for the pristine epoxy polymer and the exfoliated epoxy-clay nanocomposites prepared from three different kinds of organomontmorillonites. (From Ref. 40.)... 

T. Lan, T.J. Pinnavaia, Mechanism of clay tactoid exfoliation in epoxy-clay nanocomposites, Chem. Mater., vol. 7, pp. 2144-2150,1995. 

Reinforcement of the epoxy-clay nanocomposites was also dependent on the clay loading as shown in Fig. 29. Thus for epoxy CH3(CH2)17NH3+-MMT nanocomposite system, the tensile strength and modulus increased nearly linearly with clay loading. More than a tenfold increase in strength and modulus could be realized by the addition of ca. 15 wt % of the exfoliated organoclay. 

Kornmann, X., Berglund, L. A., and Lindberg, H., Stiffness improvements and molecular mobility in epoxy-clay nanocomposites. Mater. Res. Soc. Symp. Proc., 128, CC11.8 (2000). 

Har Harada, M., Miyamoto, T., Ochi, M. Clay dispersibility and mechanical property of the epoxy/ clay nanocomposites prepared by different treatment methods. J. Polym. Sci. Part B - Polym. Phys. 47 (2009) 1753-1761... 

WangZ, Massam J, PinnavaiaTJ (2000) Epoxy-Clay Nanocomposites, in Polymer-Clay Nanocomposites. PinnavaiaTJ, Beall GW (eds), WUey, Chichester, p. 127... 

Conductive polymer nanocomposites may also be used in different electrical applications such as the electrodes of batteries or display devices. Linseed oil-based poly(urethane amide)/nanostuctured poly(l-naphthylamine) nanocomposites can be used as antistatic and anticorrosive protective coating materials. Castor oil modified polyurethane/ nanohydroxyapatite nanocomposites have the potential for use in biomedical implants and tissue engineering. Mesua ferrea and sunflower seed oil-based HBPU/silver nanocomposites have been found suitable for use as antibacterial catheters, although more thorough work remains to be done in this field. ° Sunflower oil modified HBPU/silver nanocomposites also have considerable potential as heterogeneous catalysts for the reduction of nitro-compounds to amino compounds. Castor oil-based polyurethane/ epoxy/clay nanocomposites can be used as lubricants to reduce friction and wear. HBPU of castor oil and MWCNT nanocomposites possesses good shape memory properties and therefore could be used in smart materials. ... 

G. Das and N. Karak, Vegetable oil ased flame retardant epoxy/clay nanocomposites , Polym Degrad Stab, 2009, 94,1948-54. 

FIGURE 33.4. Comparison of flexural modulus between a pure epoxy and a 5% loaded epoxy/clay nanocomposite utilizing dynamic mechanical analysis. 

Saitoh, K., Ohashi, K., Oyama, T., Takahashi, A., Kadota, J., Hirano, H. Development of high-performance epoxy/clay nanocomposites by incorporating novel phosphonium modified montmorillonite. J. Appl. Polym. Sci. 122, 666 (2011)... 

Lee, K.Y., Kim, K.Y., Hwang, I.R., Choi, Y.S., Hong, C.H. Thermal, tensile and morphological properties of gamma-ray irradiated epoxy-clay nanocomposites toughened with a liquid rubber. Polymer. Test. 29, 139-142 (2010)... 

Images shown are examples for composites with (a) dissolved PPO in epoxy matrix (b) phase separated PPO-stearate spheres in epoxy matrix (c) PPO-modified epoxy/clay nanocomposite (d) PPO-stearate-modified epoxy/clay nanocomposite. Reprinted with permission from J. Frohlich, R. Thomann and R. Mulhaupt, Macromolecules, 2003, 36, 7205 2003, American Chemical Society... 

Wang, L., Wang, K., Chen, L., He, C., Wang, L. and Zhang, Y. (2006), Hydrothermal effects on the thermomechanical properties of high performance epoxy/clay nanocomposites . Polymer Engineering and Science, Vol. 46, pp. 296-299. 

In this paper, we describe the mechanism for formation of epoxy-clay nanocomposites and compare the tensile properties of the intercalated and exfoliated forms of these nanocomposites. 

In order to assess the benefit of clay exfoliation in the epoxy matrix, the tensile stren s and moduli for the amine-cured epoxy-clay nanocomposites have been determined for loadings in the range 1 - 2 wt %. For the pristine amine-cured epoxy matrix, the tensile strength is 90 MPa and the tensile modulus is 1.1 GPa. Comparing the mechanical properties of the exfoliated and intercalated nanocomposite in Figure 6, we find that the exfoliated nanocomposites show improved performance, especially in the modulus, relative to the pristine polymer. 

Figure 5. X-ray powder diffraction patterns of amine-cured epoxy-clay nanocomposites formed from montmorillonite clays (5 wt%) containing primary, secondary, tertiary and quaternary onium ions widi a n-C18 chain lengths.

Figure 6. Dependence of tensile strength and modulus of amine-dired epoxy-clay nanocomposites on onium ion carbon number at clay loadings of 2 wt%.

Epoxy-clay nanocomposites differ from the polyamide-6-clay system fundamentally, because the epoxy system forms a cross-linked material during polymerization. A study of the mechanism of exfoliation in epoxy-clay nanocomposites (82) showed that the gel time of the epoxy outside of the clay galleries constituted the time Umit available for exfoliation. At that time, of course, the viscosity of the system approaches infinity. 

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