Polymer nanocomposites carbon nanotubes dispersion

Masuda, J. and Torkelson, J. M. 2008. Dispersion and major property enhancements in polymer/ multiwall carbon nanotube nanocomposites via solid-state shear pulverization. Macromolecules 41 5974-5977. 

The UV-visible absorption of nanocomposites of poly(L-lysine) and single walled carbon nanotubes was studied by Kim et al. [22]. The carbon nanotubes in water showed an absorption peak at 254 nm, which is typical for this kind of material. For the carbon nanotubes dispersed in the polymer the absorbance occurred at 207 and 266 nm, while the pure poly(L-lysine) showed an absorbance maximum at 219 nm. The peaks of nanocomposite were shifted to shorter wavelengths due to the wrapping of the polymer. The authors suggested that this support the existence of significant van der Waals interactions between the polymer and the nanotubes. 

CNTs can enhance the thermal properties of CNT-polymer nanocomposites. The reinforcing function is closely associated with the amount and alignment of CNTs in the composites. Well-dispersed and long-term stable carbon nanotubes/ polymer composites own higher modulus and better thermal property as well as better electronic conductivity (Valter et al., 2002 Biercuk et al., 2002). Both SWNT and MWNT can improve the thermal stability and thermal conductivity of polymer, the polymer-CNT composites can be used for fabricating resistant-heat materials. 

As another example, Kashiwagi et al.7 have investigated the flammability of polymer/single wall carbon nanotube (SWNT) nanocomposites. It has been observed that in the case where the nanotubes were relatively well-dispersed, a nanotube containing network structured layer was formed without any major cracks or openings during the burning tests and covered the entire... 

Kashiwagi, T., Du, F., Winey, K.I., Groth, K.M., Shields, J.R., Bellayer, S., Kim, S., and Douglas, J.F. 2005. Flammability properties of polymer nanocomposites with single-walled carbon nanotubes Effects of nanotube dispersion and concentration. Polymer 46(2) 471 181. 

Grossiord, N., Loos, J., Regev, O., and Koning, C. E. Toolbox for dispersing carbon nanotubes into polymers to get conductive nanocomposites, Chem. Mater. (2006), 18, 1089-1099. 

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 viscoelastic properties of carbon nanotube/polymer composites have both practical importance related to composite processing and scientific importance as a probe of the composite dynamics and microstructure. The viscosity for CNT/PU dispersion at mixing is also very important for in-situ formation of polyurethane nanocomposite. Lower viscosity means a better flow ability and more homogenous mixing with isocyanate. Furthermore, low viscosity is very helpful to remove the bubbles before curing, which is a key step for polyurethane preparation. 

This chapter is an overview of the synthesis and properties of PVA/ nanotube composites. Various films and fibers have been processed from carbon nanotube and PVA dispersions. Compared to other polymers, PVA exhibit particularly strong interaction with single-walled as well as multiwalled carbon nanotubes. This leads to unique properties which are not observed in other nanotube polymer nanocomposites. In particular, this literature review confirms... 

Nanoparticles or nanofillers are collective terms for modified layered silicates (organoclay), graphite nanoflakes, carbon nanotubes, and a number of materials dispersed in the polymer matrix, when the particles size is in order of nanometers (one thousands of micron), or tens of nanometers. A plastic filled with nanoparticles, typically in the range of 2-10% (w/w) is called a nanocomposite. 

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