Oxygen permeability nanocomposites

It was registered above 200°C the effective formation of intermolecular chemical cross-links in the PE-MMT nanocomposite, as a result of recombination reactions of the products of radical decomposition of hydroperoxides, caused by deficiency of oxygen in a polymeric matrix due to the lowered oxygen permeability. 

Clay nanocomposites are also being developed as barrier coatings for film and for containers. The nanocomposite is deposited on the film from a solution of PVOH/ EVOH copolymer in a mix of water and isopropyl alcohol which has been used in a supersonic dispersion system to nano-disperse 7 nm diameter silica and titanium dioxide particles. The ratio of polymer to silica depends on the barrier properties required. Typical microgravure equipment can be used to coat the solution onto a plastic substrate. The result reportedly is a transparent barrier coating which is superior to silica- and alumina-coated films, and is comparable to aluminum-coated materials. Oxygen permeability at a coating thickness of 2 pm is less than 1 cc/m d atm, and moisture permeation less than f g/m d. Costs are reported to be competitive with ceramic coatings [4]. 

The relative permeability of the elastomers decreases with increase in nano-clay incorporation by several folds. The significant decrease in oxygen permeability of isobutylene-copolymer nanocomposites replaces traditional inner-liners of tires for truck applications [113]. 

The oxygen permeability in general decreases by 50 percent in polyamide matrix on nano-clay incorporation. Clay-polyamide nanocomposites can be used for packaging of processed meats, cheese, confectionery, cereals and boil-in-the-bag foods also for extrusion-coating applications in association with paperboard for fruit juice and dairy products, together with co-extrusion processes for the manufacture of beer and carbonated drink bottles (www.tifac.org). The nanocomposite packaging enhances the shelf life of many types of food. 

Relative oxygen permeability of nanocomposites with imidazolium modified montmorillonite as a function of filler volume fraction. The permeation behavior is compared with composites containing dioctadecyldimethylammo-nium ions [22] ( ) Ammonium and (a) Imidazolium composites. The dotted lines only serve as guides. (Reproduced from Mittal, V., Eur. Polym. /., 43, 3727, 2007. With permission from Elsevier.)... 

Barrier properties of a rubber matrix are remarkably improved thanks to clay addition. The tortuous path model is proposed to explain this phenomenon. In a NR/Mt nanocomposite prepared from emulsion blending, 1, 2 and 3 phr of clay led to more than 35% and to about 45% and 50% reduction of oxygen permeability, respectively. " 3 phr of OC (Mt/ didodecyl methyl amine) gave a 50% reduction of the oxygen permeability and a 40% reduction of toluene absorption at 20 °C. About 10% and 15% reduction of oxygen permeability were obtained with 5 and 10 phr of OC, respectively, and 30% reduction of toluene absorption was achieved with 15% OC, at 30 °C. ... 

Figure 13.34 A plot of oxygen permeability of 10-mil thick amorphous compression molded films vs. clay loading, tor a series of polyester nanocomposites. PETG is glycol-modified poly(ethylene terephthalate), PET is poly(ethylene terephthalate), and PEN is poly(ethylene naphthalate). The effective aspect ratio of these composites is in the range of 150-200.

In nanocomposites, several studies have reported the efficiency of nanoclay incorporation in improving mechanical properties and decreasing water vapor (Muller et al. 2011 Sadegh-Hassani and Nafchi 2014), and oxygen permeability (O2P) (Tjong 2006 Lu and Mai 2007). 

In the same study by Soheilmoghaddam et al. (2014a, b) the oxygen (O2) permeability values of RC film and RC/GNS nanocomposite films was reported. The oxygen permeability values for the nanocomposite films decreased with the... 

Figure 21.15 Oxygen permeability of polyamide 6 nanocomposites as a function of C30B concentration. Swain and Isayev [62]. Reproduced with permission of John Wiley and Sons.

Figure 21.16 Relative oxygen permeability for the PP/EVA nanocomposites as a function of clay (C15A) loading. Shafiee et al. [63]. Reproduced with permission of Taylor and Francis.

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