Mechanical properties epoxy nanocomposites

T.J. Pinnavaia, T. Lan, Z. Wang, H. Shi and P.D. Kaviratna, Clay-reinforced epoxy nanocomposites Synthesis, properties, and mechanism of formation. In G.-M. Chow and K.E. Gonsalves (Eds.), Nanotechnology Molecularly Designed Mlaterials, American Chemical Society, Washington, 1996, Vol. 622, p. 250. 

S. Dutta, N. Karak, J. P. Saikia and B. Konwar, Biocompatible epoxy modified bio-based polyurethane nanocomposites mechanical property, cytotoxicity and biodegradation , Bioresour Technol, 2009,100, 6391-7. 

Pinnavaia, T. J. Lan, T. Wang, Z. Shi, H. Kaviratna, P. D., Clay-Reinforced Epoxy Nanocomposites Synthesis, Properties, and Mechanism of Formation. 

Literature search shows that epoxy-based nanocomposites have been prepared by many researchers [34-38]. Becker et al. have prepared nanocomposites based on various high-functionahty epoxies. The mechanical, thermal, and morphological properties were also investigated thoroughly [39 3]. The cure characteristics, effects of various compatibilizers, thermodynamic properties, and preparation methods [16,17,44 9] have also been reported. ENR contains a reactive epoxy group. ENR-organoclay nanocomposites were investigated by Teh et al. [50-52]. 

The effect of polymer-filler interaction on solvent swelling and dynamic mechanical properties of the sol-gel-derived acrylic rubber (ACM)/silica, epoxi-dized natural rubber (ENR)/silica, and polyvinyl alcohol (PVA)/silica hybrid nanocomposites was described by Bandyopadhyay et al. [27]. Theoretical delineation of the reinforcing mechanism of polymer-layered silicate nanocomposites has been attempted by some authors while studying the micromechanics of the intercalated or exfoliated PNCs [28-31]. Wu et al. [32] verified the modulus reinforcement of rubber/clay nanocomposites using composite theories based on Guth, Halpin-Tsai, and the modified Halpin-Tsai equations. On introduction of a modulus reduction factor (MRF) for the platelet-like fillers, the predicted moduli were found to be closer to the experimental measurements. 

Bandyopadhyay et al. [138] have also studied the distribution of nanoclays such as NA and 30B in NR/ENR (containing 50 mol% epoxy) and NR/BR blends and their effect on the overall properties of the resultant nanocomposite blends. They calculated the preferential distribution of clays at various loadings in the blend compounds from the viscoelastic property studies from DMA. The tensile properties of the 50 50 NR/ENR and 50 50 NR/BR blend nanocomposites are shown in Table 5. It is apparent that in both the blends that the mechanical properties increase with increasing clay concentration up to a certain extent and then decrease. These results have been found to depend on matrix polarity and the viscosity of the blend compounds. 

Incorporation of monofunctional epoxy POSS into an amine-cured epoxy network increased and broadened the Tg without changing the crosslink density and enhanced the thermal properties. Additionally, it was found that the thermal and thermal-mechanical properties of resultant styrene-POSS vinylester resin nanocomposites were dependent on the percentage of POSS incorporated into the resin [171]. Over a range of POSS incorporations, the Tg of the copolymers changed very little, but the flexural modulus increased with increasing POSS content. 

Technology for preparing nanocomposites directly via compounding has been investigated by Vaia, Ishii, and Giannelis. Industrial R D efforts have focused on process technology (e.g., melt or monomer exfoliation processes), as there are a number of polymers (e.g., polyolefins) that do not lend themselves to a monomer process. Nanocomposites with a variety of polymers, including polyacrylates or methacrylates, polystyrene, styrene-butadiene rubber, epoxy, polyester, and polyurethane, are amenable to the monomer process. The enhancement of mechanical properties, gas permeability resistance, and heat endurance are the primary objectives for the application of PCN, and their success will establish PCNs as a major commercial product. 

Becker, O., Cheng, Y.-B., Varley, R. J., and Simon, G. R, Layered silicate nanocomposites based on various high functionality epoxy resins the influence of cure temperature on morphology, mechanical properties and free volume, Macmmolecules, 36,1616-1625 (2003). 

Chen, J. -S., Pohks, M. D., Ober, C. K., Zhang, Y., Wiesner, U., and Giannelis, E., Study of the interlayer expansion mechanism and thermal-mechanical properties of surface-initiated epoxy nanocomposites. Polymer, 43, 4895-4904 (2002). 

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... 

Kay Kaynak, C., Nakas, G. L, Isitman, N. A. Mechanical properties, flammability and char morphology of epoxy resin/montmorillonite nanocomposites. Appl. Clay Sci. 46 (2009) 319-324. 

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