Clay chemistry

Several elements from the multielement suite are associated with alteration and clay chemistry. Due to the relative cleanliness of the Athabasca Group sandstones, anomalous contents of aluminium, magnesium, potassium, lithium, and boron, along with loss-on-ignition, provide measures of the amount and type of alteration present. These data... 

I was lucky to receive some jars of sodium-substituted Eucatex vermiculite and n-butylammonium-substituted Eucatex vermiculite. These synthetic systems had been obtained by cation exchange on the raw minerals. Such cation exchange plays a major role in clay chemistry, and the process is described in detail in standard books on clay colloids, like that of van Olphen [2], Some years later, I was able to obtain the following chemical formula for the dry sodium Eucatex vermiculite [3]... 

Dr. Julia M. Clay Chemistry Department Princeton University Princeton, NJ, 08544-1009... 

Nahin, P. G., Perspectives in Applied Organo-Clay Chemistry, Clays and Clay Miner, (1963) 10, 257-271. 

Polymer clay nanocomposites are already used in many applications to enhance existing properties of a particular material, and development should be focused on the true multifunctional materials. Certainly, clay nanocomposites will continue to be used for enhanced mechanical, flammability, and gas barrier properties, but fundamental limits in clay chemistry prevent them from being used easily in applications requiring electrical/ thermal conductivity or optical properties. Similarly, combinations of... 

In mineralogy, the term clay is used for a variety of polycrystaUine materials that are well described in clay science, mineralogy properties, and characterization textbooks [2-5]. Clays can be present in fibrous, tubular, lath shaped, and planar geometries. In this chapter, however, our focus will be mainly on the planar clay varieties called smectites that include montmorillonites, the most commonly used clay for the produchon of polyolefin-clay nanocomposites. In this section, we wiU focus on clay characteristics that are relevant to catalyst supporting and particle break-up during polymerization clay chemistry, crystalline structure, and geometry. 

KHL Nulens, H Toufar, GOA Janssens, RA Schoonheydt, CT Johnston. The latest frontiers of clay chemistry proceedings of the Sapporo conference on the chemistry of clays and clay minerals (Sapporo, Japan, 1996). A Yamagishi, A. Aramata, M. Taniguchi, eds. Sendai The smectite forum of Japan, 1998 116. 

Secondly, we need to consider the position of the modifier. The clay chemistry dictates that conventional onium ions will only become firmly attached to the basal plate surfaces, leaving the edges and other faces untreated. These untreated surfaces will probably have sites amenable to treatment with more conventional additives, such as organo-silanes. Thus, mixed surface treatments may be most effective in covering all active surface sites. Indeed, it has been reported that all common mineral fillers are amphoteric to some extent and therefore have sites for adsorbing both acidic and basic surface treatment additives [26]. 

Mackenzie Robert Cameron (1920 2000) Scot, chem.., expert in clay chemistry, founder of International confederation on thermal analysis (ICTA)... 

Because the crystal structure of clay minerals plays a very large role in determining the way a clay will interact with aqueous solutions, a review of clay mineral surface chemistry must, by necessity, begin with a brief outline of the chemical origins of clay mineral structures. From this basis we will outline the role of edge-site chemical interactions and, subsequently, the controls on ion exchange. This overview of clay chemistry will conclude with a survey outlining how the various site interactions determine the macroscopic behavior of a number of elays in natural systems. 

PVB appreciates the efforts of Professor H. C. Helgeson, die fellow who introduced him to clay chemistry many years ago, as well as the support of DOE/BES-Geo-sciences and the US Nuclear Regulatory Commission. This work was supported by the United States Department of Energy under contract DE-AC04-94AL85000. 

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