Applied Clay Science 

Abstract: An overview of polymer–clay hybrid nanocomposites is provided with emphasis placed on the use of alkylammonium exchanged smectite clays as the reinforcement phase in selected polymer matrices. A few weight percent loading of organoclay in nylon 6 boosts the heat distortion temperature by 80°C, making possible structural applications under conditions where the pristine polymer would normally fail. A similar loading of clay nanolayers in elastomeric epoxy and polyurethane matrices dramatically improves both the toughness and the tensile properties of these thermoset systems. Glassy epoxy nanocomposites exhibit substantial improvement in yield strength and modulus under compressive stress–strain conditions. The latest development in polypropylene hybrids have yielded nanocomposites with improved storage moduli. Polyimide hybrids in thin-film form display a 10-fold decrease in permeability toward water vapor at 2 wt.% clay loading. In situ and melt intercalation processing methods are effective in producing reinforced polystyrene hybrids. Nitrile rubber hybrids show improved storage moduli and reduced permeabilities even toward gases as small as hydrogen. Poly(e-caprolactone)–clay nanocomposites prepared by in situ polymerization of e-caprolactone in organoclay galleries show a substantial reduction in water adsorption. Polysiloxane nanocomposites produced from poly(dimethylsiloxane) and organoclay mixtures have improved in tensile properties, thermal stability and resistance to swelling solvents. Organoclay-poly(l-lactide) composite film was obtained by solvent casting technique. Clay nanolayers dispersed in liquid crystals act as structure directors and form hybrids composites that can be switched from being highly opaque to highly transparent by applying an electric field of short duration.

Abstract: In the pursuit of improved approaches to fire retarding polymers, a wide variety of concerns must be addressed in addition to the flammability issues. For commodity polymers, their low cost requires that the fire retardant (FR) approach also be of low cost. This limits solutions primarily to additive type approaches. These additives must be inexpensive and easily processed with the polymer. In addition, the additive must not excessively degrade the other performance properties of the polymer, and it must not create environmental problems when recycling or at the time of its final disposal. We have recently found that polymer layered-silicate (clay) nanocomposites have the unique combination of reduced flammability and improved physical properties. This paper is intended as an overview of the research to date, by our group and others, on the use of clays, dispersed at the nanometer level, in polymers for improving thermal stability and flammability.

Abstract: Clays have been and continue to be one of the more important industrial minerals. Clays and clay minerals are widely utilized in many facets of our society. They are important in geology, agriculture, construction, engineering, process industries, and environmental applications. Traditional applications are many. Some of the more important include ceramics, paper, paint, plastics, drilling fluids, foundry bondants, chemical carriers, liquid barriers, decolorization, and catalysis. Research and development activities by clay scientists in academia, government, and industry are continually resulting in new and innovative clay products Many of these new applications are the result of improved processing, which provides clays of higher purity, more precise particle size and distribution, whiter and brighter color, modified surface chemistry, and other physical and chemical modifications. Some new and improved clay products include tailored or engineered paper coating kaolins, enhanced paint thickeners, nanocomposites for plastics, pillared clays as special absorbents and catalysts, clays for liquid fertilizer suspensions, clays for absorption of animal wastes, calcined kaolins with high brightness and low abrasion, faster casting clays, and clays with a very high modulus of rupture. Improvement of mining and processing techniques will lead to the continued growth of traditional clay applications and to the development of new and innovative clay products. Value added products are the wave of the future for the traditional industrial clay minerals.

Abstract: The objective of this paper is to give an overview of properties, synthesis and applications, and to describe the research performed until the present moment. A significant amount of research has been done in this area, including different synthesis techniques, modifications with several chemical compounds as quaternary alkylammonium salts and also biomolecules as enzymes that provide applicability in a variety of fields. The review is particularly focused on bentonite and polymer nanocomposites, an important area of the nanotechnology.

Abstract: Methylene blue was adsorbed on kaolin from a local deposit. The raw kaolin itself was a relatively good adsorbent. The adsorption capacity was improved by purification and by treatment with NaOH solution. Calcination of the kaolin reduced the adsorption capacity. The adsorption data could be fitted by the Freundlich and Langmuir equations. Also, the thermodynamic parameters such as ΔH0, ΔS0 and ΔG0 were determined.