Colloidal elastic properties

Rubber is a natural polymer and possesses elastic properties. It is also termed as elastomer and has a variety of uses. It is manufactured from rubber latex which is a colloidal dispersion of rubber in water. This latex is obtained from the bark of rubber tree and is found in India, Srilanka, Indonesia, Malaysia and South America. 

H.M. Princen Rheology of Foams and Highly Concentrated Emulsions I. Elastic Properties and Yield Stress of a Cyhndrical Model System. J. Colloid Interface Sci. 91, 160 (1983). 

The stabilising action of the adsorption layers from high molecular substances (protective colloids) is related to the decrease in the forces of molecular attraction. Hence, films from aqueous solution of polyvinyl alcohol obtained between drops of cyclohexane have thickness of 80 nm and respectively, a very low attraction force, in contrast to black films [513]. Along with that the adsorption layers from such compounds possess visco-elasticity properties with modulus of elasticity 104 N m"2, impeding the film thinning and drop coalescence [503]. 

Sonntag, R.C., and Russel, W.B. (1987). Elastic properties of flocculated networks. Journal of Colloid and Interface Science. 116 485 89. 

Wu, H., and Morbidelli, M. (2001). A model relating structure of colloidal gels to their elastic properties. Langmuir. 17 1030-1036. 

At this voliime fraction, the viscosity diverges because the shear stress is now given by the particle-particle contact in the tightly packed structure. As a result, we obtain a fluid with visco-elastic properties similar to polymeric solids. In ceramic processing, we extrude and press these pastes into green shapes. As a result, the rheology of ceramic pastes is of importance. The rheology of very concentrated suspensions is not particularly well developed, with the exception of model systems of monodisperse spheres. This section first discusses visco-elastic fluids and second the visco-elastic properties of ceramic pastes of monodisperse spheres. The material on visco-elastic fluids draws heavily from the book Colloidal Dispersions by Russel, Saville, and Schowalter [31]. 

Princen HM. Rheology of foams and highly concentrated emulsions. I. Elastic properties and yield stress of a cylindrical model system. J Colloid Interface Sci 1983 91 160-175. 

When De is very large, the system behaves like a solid and has elastic properties when De is very small, it flows like a liquid. The importance of rheology in studying colloidal dispersions arises from the fact that De is often around unity so that a wide range of visco-elastic phenomena are observed. 

For TIN3 the interpretation of the radiation-induced expansion is more complex. The contraction or, at the least, lack of expansion in the a direction indicates that the nonisotropic radiation-induced expansion cannot be attributed simply to the elastic properties. It is possible that the metal colloids and/or N2 clusters in TIN3 are in the form of platelets in planes perpendicular to the c direction. Expansion would then occur in the c direction, and elastic considerations could account for the apparent contractions in the a directions. Optical studies are especially desirable in this case to determine the shape of the colloids. 

Many industrial products use mixtures of both surfactant and polymer molecules or surfactant and colloid. Although the effects of polymer on the phase behavior and structure of surfactant phases have begun to be investigated in microemulsions, lamellar phases, and vesicle phases, further experimental work in mixed systems is necessary to understand how the polymer or the colloid modifies the elastic properties of the surfactant film. 

Kruger, J.K., Grammes, C., Stockem, K. et al. (1991) Nonlinear elastic properties of solid polymers as revealed by Brillouin spectroscopy. Colloid. Polym. Sci., 269, 764,... 

Llorente MA, Andrady AL, Mark JE. Model networks of end-linked polydimethylsiloxane chains. XIII. The effects of junction fimctional-ity on the elastic properties of the bimodal networks. Colloid Polym Sci 1981 259 1056-61. 

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