In polymer nanocomposites

A nanocomposite is defined as the composite of two materials, one having the dimension of nanometric level at least in one dimension. In polymer nanocomposites (PNC), the fillers are dispersed on a nanolevel. 

The dynamic mechanical thermal analyzer (DMTA) is an important tool for studying the structure-property relationships in polymer nanocomposites. DMTA essentially probes the relaxations in polymers, thereby providing a method to understand the mechanical behavior and the molecular structure of these materials under various conditions of stress and temperature. The dynamics of polymer chain relaxation or molecular mobility of polymer main chains and side chains is one of the factors that determine the viscoelastic properties of polymeric macromolecules. The temperature dependence of molecular mobility is characterized by different transitions in which a certain mode of chain motion occurs. A reduction of the tan 8 peak height, a shift of the peak position to higher temperatures, an extra hump or peak in the tan 8 curve above the glass transition temperature (Tg), and a relatively high value of the storage modulus often are reported in support of the dispersion process of the layered silicate. 

Tomasko DL, Han XM, Liu DH, Gao WH (2003) Supercritical fluid applications in polymer nanocomposites. Curr Opin Solid State Mater Sci 7 407 112... 

R. A. Vaia, B. B. Sauer, O. K. Tse, and E. P. Giannelis, Relaxations of confined chains in polymer nanocomposites Glass transition properties of poly(ethylene oxide) intercalated in montmorillonite, J. Polym. Sci. B Polym. Phys. 35(1), 59-67 (1997). 

B. Schartel, M. Bartholmai, and U. Knoll, Some comments on the main fire retardancy mechanisms in polymer nanocomposites, Polym. Adv. Technol., 2006, 17 772-777. 

S. Peeterbroeck, F. Laoutid, B. Swoboda, J.-M. Lopez-Cuesta, N. Moreau, J.B. Nagy, M. Alexandre, and Ph. Dubois, How carbon nanotube crushing can improve flame retardant behavior in polymer nanocomposites, Macromol. Rapid. Commun., 2007, 28 260-271. 

Additional reports [82] revealed that the volume concentrations of CB can be precisely determined using HAADF-STEM. In another study, the same authors reported that the filler distribution in polymer nanocomposite systems could be clearly determined [83]. They also observed the nanoscale organization in a photoactive layer of a polymer solar cell that could not be seen with CTEM [79]. 

Thus, the aforementioned used nanoscopic methodics allow estimating both interfacial layer and structural special features in polymer nanocomposites and its sizes and properties. For the first time it has been shown that two consecutive interfacial layers are formed in elastomeric particulate-filled nanocomposites, which are reinforcing elements for the indicated nanocomposites. The proposed theoretical methodics of interfacial layer thickness estimation, elaborated within the fiamewoiks of finctal analysis, give well enough correspondence to the experiment. 

Carbon nanotubes (CNTs) and carbon nanofibers (CNFs), due to their unique structure and properties, appear to offer quite promising potential for industrial application [236]. As prices decrease, they become increasingly affordable for use in polymer nanocomposites as structural materials in many large scale applications. In fact, three applications of multiwall CNT have been discussed recently first, antistatic or conductive materials [237] second, mechanically reinforced materials [238,239] and third, flame retarded materials [240,241]. The success of CNTs in the field of antistatic or conductive materials is based on the extraordinary electrical properties of CNTs and their special geometry, which enables percolation at very low concentrations of nanotubes in the polymer matrix [242]. 

Colister, J. 2002. Commercialization of polymer nanocomposites. In Polymer Nanocomposites Sunthesis, Characterization, and Modeling, R. Krishnamoorti and R.A. Vaia, eds.. In ACS Symposium Series No. 804, pp. 11-79, American Chemical Soc, Washington, DC. 

Besides, within the finmeworks of the fractal model of interfacial layer formation in polymer nanocomposites it has been shown that between (p and (p the following relationship exists ... 

Rittigstein, R, and Torkelson, J. M., Polymer-nanoparticle interfacial interactions in polymer nanocomposites confinement effects on glass transition temperature and suppression of physical ageing, J. Polym. Sci. Polym. Phys., 44, 2935-2943 (2006). 

Lu, H., and Nutt, S., Restricted relaxation in polymer nanocomposites near the glass transition. Macromolecules, 36,4010-4016 (2003). 

Bousmina, M., Study of intercalation and exfoliation processes in polymer nanocomposites. Macromolecules, 39, 4259-4263 (2006). 

Zhang, Q., and Archer, L. A., Monte Carlo simulation of structure and nanoscale interactions in polymer nanocomposites, J. Chem. Phys., 121, 10814—10824 (2004). 

Scott, W. W. and Bhushan, B. 2003. Use of phase imaging in atomic force microscopy for measurement of viscoelastic contrast in polymer nanocomposites and molecularly thick lubricant films. 

Paulis M, Leiza JR (2009) In Mittal V (ed) Advances in polymer nanocomposites technology Nova, New York, chap 5... 

The mechanism of the improvement of thermal stability in polymer nanocomposites is not fully understood. It is often stated [126-129] that enhanced thermal stabihty is due to improved barrier properties and the torturous path for volatile decomposition products, which hinders their diffusion to the surface material where they are combusted. Other mechanisms have been proposed, for example, Zhu et al. [130] recently proposed that for polypropylene-clay nanocomposites, it was the structural iron in the dispersed clay that improved thermal stability by acting as a trap for radicals at high temperatures. 

During the past decades, nanotechnology has attracted great attention due to its marvellous potential applications in numerous areas [90]. Polymer nanocomposite is a unique addition in the nanotechnology family. In polymer nanocomposite, one phase is dispersed in another phase in nanometer level [19]. Different types of reinforcing fillers such as sodium montmo-rillonite, sodium bentonite, layered double hydroxide, exfohated graphite, fullerene, carbon nanofiber, and carbon nanotube have been successfully used in the preparation of polymer nanocomposites [19]. Recently,... 

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