Dispersion polymer-carbon nanotubes

At the steps before the elaboration of carbon nanotube nanocom-posites, wet-STEM can be used for the characterization of nanotubes dispersed in a liquid (see Figure 3.18), and for polymer latex/ nanotubes mixing (before evaporation or freeze-drying to elaborate polymer/carbon nanotube nanocomposites). 

The gap between the predictions and experimental results arises from imperfect dispersion of carbon nanotubes and poor load transfer from the matrix to the nanotubes. Even modest nanotube agglomeration impacts the diameter and length distributions of the nanofillers and overall is likely to decrease the aspect ratio. In addition, nanotube agglomeration reduces the modulus of the nanofillers relative to that of isolated nanotubes because there are only weak dispersive forces between the nanotubes. Schadler et al. (71) and Ajayan et al. (72) concluded from Raman spectra that slippage occurs between the shells of MWNTs and within SWNT ropes and may limit stress transfer in nanotube/polymer composites. Thus, good dispersion of CNTs and strong interfacial interactions between CNTs and PU chains contribute to the dramatic improvement of the mechanical properties of the... 

Uddin, N. M., Capaldi, F. M., Farouk, B. (2011). Molecular dynamics simulations of the interactions and dispersion of carbon nanotubes in polyethylene oxide/water systems. Polymer. 52(2), 288-296. 

Y.Y. Huang, E.M. Terentjev, Dispersion of carbon nanotubes mixing, sonication, stabilization, and composite properties. Polymers 4 (2012) 275. 

Due to the van der Waals interaction, the nanotubes tend to aggregate to form bundles or ropes and further agglomerate when dispersed in the polymer matrix. The high surface area of the nanotubes also results in a high viscosity of the nanotube/polymer mixture particularly when fabricating the nanocomposite with high loading level of the nanotubes, which makes the dispersion of the nanotubes extremely difficult. The dispersion of carbon nanotubes in the polymer matrix can be made by several techniques. 

Kasaliwal, G. Villmow, T Pegel, S Potsehke, P. Influenee of material and proeessing parameters on carbon nanotube dispersion in polymer melts. In Polymer-carbon nanotube composites, preparation, properties and applications, MeNally, T. Potsehke, R, eds Woodhead Publishing Cambridge, UK, 2011 pp. 92-132. 

The successful incorporation of CNTs into various polymer matrix hosts is the first step on the road towards commercial application of polymer-carbon nanotube composites. Thereby the main objective is to disperse and distribute the individual CNTs within the polymer matrix host. However, due to the already mentioned entangled agglomerate structures and high van der Waals forces this is a challenging task. For thermoplastic materials four different processing routes are principally used ... 

Pegel S, Villmow T and POtschke P (2011) Quantification of dispersion and distribution of carbon nanotubes in polymer composites using microscopy techniques, in Polymer-carbon nanotube composites Preparation, properties and applications (Eds. McNally T and Pbtschke P), Woodhead Publishing Limited, Cambridge, UK, pp. 265-294. 

For melt-compounded nanocomposites, the screw rotation speed of an extruder has a large influence on the dispersion of carbon nanotubes in the polymer matrix. Chen et al employed an ultrahigh-shear extruder to mix pristine MWNTs with PVDF pellets at a screw speed of 1000 rpm (1470 [62]. For the purpose of comparison, the MWNT/PVDF... 

Grady B P (2010) Recent developments concerning the dispersion of carbon nanotubes in polymers, Macromol Rapid CommMn 31 247-257. 

Esawi A M K, Salem H G, Hussein H M and Ramadan A R (2010) Effect of processing technique on the dispersion of carbon nanotubes within polypropylene carbon nanotube composites and its effect on their mechanical properties, Polym Compos 31 772-780. 

Etika K C, Cox M A and Grunlan J C (2010) Tailored dispersion of carbon nanotubes in water with pH-responsive polymers. Polymer 51 1761-1770. 

Hobbie et al. (2003) used optical measurements of semi-dilute dispersions of polymer dispersed multiwalled carbon nanotubes to determine that for a weakly elastic polymer melt, the tubes aligned preferentially parallel to the flow direction at low stresses with a transition to alignment with the vorticity vector above a critical... 

Zhang QH, Fang F, Zhao X, Li YZ, Zhu MF, Chen DJ (2008) Use of dynamic rheological behavior to estimate the dispersion of carbon nanotubes in carbon nanotube/polymer composites. J Phys ChemB 112 12606... 

Li N, Zhang F, Wang J et al (2009) Dispersions of carbon nanotubes in sulfonated poly[bis(benzimida-zobenzisoquinolinones)] and their proton-conducting composite membranes. Polymer 50 3600-3608... 

Magnetic force microscopy (MFM) has been used for characterising the dispersion of carbon nanotubes (CNT) in a high performance polymer matrix [331]. 

Thomassin J., Vuluga D., Alexandre M., Jerome C., Molenberg I., Huynen I., and Detrembleur C., A convenient rout for the dispersion of carbon nanotubes in polymers Application to the preparation of electromagnetic interference (EMI) absorbers. Polymer 2012, 53, 169-174. 

Liu C-X, Choi J-W. Improved dispersion of carbon nanotubes in polymers at high concentrations. 

Chen H, Muthuraman H, Stokes P, Zou J, Liu X, Wang J, et al. Dispersion of carbon nanotubes and polymer nanocomposite fabrication using trifluoroacetic acid as aco-solvenL Nanotechnology 2007 18 1-9. 

Polymer blends, nanocomposites, dispersion, clay, carbon nanotubes, nanoparticles, solid-state shear pulverization. 

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