Thermodynamic properties-cellulose

The bulk properties of celluloses are generally influenced by adsorbed moisture. The effect of the change in bulk solid properties for microcrystalline cellulose has been demonstrated by a tableting operation in a very simplistic manner. Dry microcrystalline cellulose (%MC = 0.07) was compared with material with a moisture content above that associated with completion of the monolayer (%MC = 5.1). A thermodynamic picture of the character of water in these samples can be based on the adsorbate thermodynamic properties A// > 3.5kcal/mole (14.65 kJ/mole),... 

Bergman, R. Simdelof, Z.O. (1977). Diffusion transjxrrt and thermodynamic properties in concentrated water solutions of hydroxypropyl cellulose at temperatures up to phase separation. Eur. Polym. /., Vol. 13, No. 6, pp. 881-889. 

JEF Jeffries, R., The thermodynamic properties of mixtures of secondary cellulose acetate and its solvents, Trans. Faraday Soc., 53, 1592,1957. 

M02 Moore, W.R. and Shuttleworth, R., Thermodynamic properties of solutions of cellulose acetate and cellulose nitrate, J. Polym. Sci. Part A, 1, 733, 1963. 

Thermodynamic Properties of Solutions of Long Chain Compounds. Cellulose and Cellulose Derivatives, edited by Elnil Ott, Interscience Publishers, Inc., N.Y. (19 3), pp 893-909-Cellulose and Cellulose Derivatives, edited by Emil Ott, Interscience Publishers, Inc., N.Y. (19 3), pp 9 3-955-Ind. Eng. Chem.,35, 980 (19 3). Reprinted in Rub. Chem. and Tech., 11, 38 (I9itlt). 

Computer simulations of ionic liquids have largely focused on the development of force field parameters specific to an ionic liquid or an ionic liquid family [17-23]. In addition to simulation of structural, dynamical, electric, and thermodynamic properties of several pure ionic liquids [24-26], the solvation of small solutes in ionic liquids has also been investigated [27-31]. Compatibility of ionic liquids and cellulose... 

The sorption of water by excipients derived from cellulose and starch has been considered by numerous workers, with at least three thermodynamic states having been identified [82]. Water may be directly and tightly bound at a 1 1 stoichiometry per anhydroglucose unit, unrestricted water having properties almost equivalent to bulk water, or water having properties intermediate between these two extremes. The water sorption characteristics of potato starch and microcrystalline cellulose have been determined, and comparison of these is found in Fig. 11. While starch freely adsorbs water at essentially all relative humidity values, microcrystalline cellulose only does so at elevated humidity values. These trends have been interpreted in terms of the degree of available cellulosic hydroxy groups on the surfaces, and as a function of the amount of amorphous material present [83]. 

Incorporation of long-chain hydrocarbon hydrophobes into a cellulose ether backbone leads to an interesting new class of polymeric surfactants. Their enhanced solution viscosity can be explained in terms of intermolecular associations via the hydrophobe moieties. Entropic forces cause the polymer hydrophobes to cluster to minimize the disruption of water structure. The same thermodynamic principles that are used to explain the micellization of surfactants can be applied to explain the solution behavior of HMHEC. HMHECs interact with surfactants that modify their solution viscosities. The chemical nature and the concentration of the surfactant dictate its effect on HMHEC solution behavior. The unique rheological properties of HMHEC can be exploited to meet industrial demands for specific formulations and applications. 

Cellulose has been dissolved in A-methylmorpholine iV-oxide at high temperature and the recrystallization of the polysaccharide upon cooling investigated." The crystallization system is analogous to the solidification of binary mixtures of polymer and diluent, which present unusual thermodynamic and morphological properties. The system provides a new method of texturing cellulose. 

Cellulose and its derivatives have o values of about 2, i.e., thermodynamically they are about as flexible as poly(isobutylene). Thus, cellulose chains are not extraordinarily stiff, although they are often assumed to be so on the basis of their high exponents in the intrinsic viscosity-molar mass relationship (see Section 9.9.7). These high exponents are interpreted as arising from the particular (high) draining properties of the cellulose molecule. 

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