Intracrystalline swelling

The chemistry of an important group of naturally occurring materials is characterized by surface reactions many clay minerals possess what can be considered surface at its extreme. All clay minerals capable of intracrystalline swelling with separation of the silicate layers are—to overstate it—surface with a silicate layer on each side. Many principles and techniques of surface chemistry were first found with clay minerals. Nevertheless, the clay minerals will not be considered in this article, except for some comparison and analogies with surface compounds. 

Hofmann, U., Weiss, G.K., Mehler, A. and Scholz, A., 1956. Intracrystalline swelling, cation exchange, and anion exchange of minerals of the montmorillonite group and of kaolinite. Proc. Natl. Conf. Clays Clay Miner. 4th - Natl. Acad. Sci. Natl. Res. Counc., Pubi, 456 273-287. 

Zeronian, S.H., Intracrystalline swelling of cellulose, in Cellulose Chemistry and Its Applications, Nevell, T.P. and Zeronian, S.H., Eds., Ellis Horwood Ltd., Chichester, England and Halsted Press, New York, 1985, chap. 6, pp. 159-180. 

II allomorph is known by the term regenerated cellulose. Regeneration involves either preparing a solution of cellulose in an appropriate solvent or of an intermediate derivative followed by coagulation and recrystallization. This process is used to produce rayon fibers. Mercerization involves intracrystalline swelling of cellulose in concentrated aqueous sodium hydroxide (NaOH), followed by washing and recrystallization. This process is used to improve the properties of natural yams and fabrics. The transition from cellulose I to cellulose II is not reversible, and fliis implies that cellulose II is a stable form as compared with the metastable cellulose I. 

Grim (1952) distinguished two modes of swelling in clay soils, namely, intercrystalline and Intracrystalline swelling. Intercrystalline swelling takes place when the uptake of moisture is restricted to the external crystal surfaces and the void spaces between the crystals. Intracrystalline swelling, on the other hand, is characteristic of the smectite family of clay... 

Exchange of sodium ions for inorganic or organic cations One-dimensional intracrystalline swelling... 

Smectites form lamellar complexes with water and with many organic molecules. This phenomenon is known as intracrystalline swelling. 

The ordered state (or semi-ordered), which resists all processes of intracrystalline swelling, does not seem to lesistdispersion. The beidellite of Black Jack Mine shows maximum dispersion when it is saturated with Na cations in water. Weir [1960] ascertains that the recuperation of this dispersed beidellite in a dry state can lead to a turbostratic structure. It must, therefore, be admitted that there is a certain instability in the ordered (or semi-ordered) arrangement. 

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