Polymer nanocomposites sorption

Low et al. carried out a series of moisture sorption experiments on polyamide 6/clay nanoeomposite film. The moisture absorption of the nanocomposites showed a maximum followed by a reduced sorption. The sorption maximum is believed to be caused by various factors, such as restricted chain relaxation in the presence of clay and moisture-induced crystallization. 

Andrade et al. investigated the transport properties and the solvent induced-crystallization phenomena in poly(ethylene terephthalate) (PET) and PET clay nanocomposites, prepared by melt intercalation. Results of non-isothermal crystallization showed that cold crystallization temperature, and percent of crystallinity of nanocomposites are higher than those of pure PET. The sorption of all die solvents is accompanied by a large-scale stmctural rearrangement, leading to the induced crystallization of the original amorphous state. The solvent induced crystallization caused an increasing of more than four times the percent of crystallinity. 

Bohning et prepared nanocomposites from solution using poly 

The structural characteristics and moisture sorption properties of two kinds of nylon-6/clay hybrids were investigated by Murase et The moisture sorption isotherms of the hybrid samples were a typical sigmoid shape similar to that of the pure nylon-6 sample, even if the extent of moisture regain of the hybrid films was comparatively low. All the isotherms obtained were explained through quantitative analysis in terms of the BET multilayer adsorption theory and complementally with the aid of the FloryHuggins solution theory. 

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Since the 1990s, mesoporous materials have attracted a great deal of attention based on their apphcations in the fields of molecular sorption, ahgnment, confinement, and the formation of nanoclusters. Unlike microporous zeohtes, these materials are usuaUy prepared via template methods, and have ordered hexagonal or cubic charmels with pore diameters ranging from 2 to 10 nm. The internal surface of the mesoporous materials can be modified by covalently anchoring a number of functional groups to their channel walls. Thus, mesoporous materials are also attractive in view not only of controlled polymerization but also the formation of polymer nanocomposites [10]. 

FIGURE 2.12 Sorption curves for different nanocomposites at 45°C (solvent methyl ethyl ketone [MEK]). (From Maiti, M. and Bhowmick, A.K., J. Appl. Polym. Sci., 105, 435, 2007. Courtesy of Wiley InterScience.)... 

Ye. P. Mamunya, V. I. Shtompel, E. V. Lebedev, P. Pissis, A. Kanapitsas, and G. Boiteux, Structure and water sorption of polyurethane nanocomposites based on organic and inorganic components, Eur. Polym. J. 40, 2323-2331 (2004). 

Nanocomposites of iron oxide and silicate were also synthesized for the degradation of azo-dye Orange II (see Table 7) [388, 389]. To improve the sorption capacity, clays were modified in different ways (e.g. treatment by inorganic and organic compounds). Organoclays have recently attracted lots of attention in a number of applications, for example, dithiocarbamate-anchored polymer/organosmectite for the removal of heavy metal ions from aqueous media (see Table 7) [390]. 

Zeppa C, Gouanve Espuche E (2009) Effect of a plasticizer on the structure of biodegradable starch/clay nanocomposites thermal, water-sorption, and oxygen-barrier properties. J App Polym Sci 112 2044-2056... 

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