Density gradients specific gravity

Different grades of both of the ABS and HIPS plastics have specific gravities in the range of 1.055-1.125 g cm-1. As a result such mixtures can not be effectively separated by density gradient procedures. 

P4. Piomelli, S., Lurinsky, G., and Wassennan, L. R., The mechanism of red cell aging. 1. Relationship between cell age and specific gravity evaluated by ultracentrifugation in a discontinuous density gradient. J. Lab. Clin. Med. 69, 659 (1967). 

When mixtures of solvents of different density are used for polymer dissolution, an equilibrium is established during ultracentrifugation where the concentration of the solvent of higher specific gravity is increased at the bottom of the cell while the specifically lighter solvent is enriched near the meniscus. Hence, the dissolved macromolecules encounter a density gradient in the cell, and they move to the place... 

D792, specific gravity and density D1505, density by density-gradient technique Optical tests... 

Saturation (v) is the volume fraction of the total void volume occupied by a specific fluid at a point. Saturation values can vary from zero to 1 with the saturation of all fluids equal to 1. Residual saturation (Sr) is the saturation at which the NAPL becomes discontinuous and immobile due to capillary forces. Residual saturation is dependent upon many factors, including pore size distribution, wettability, fluid viscosity and density ratios, interfacial surface tension, gravity and buoyancy forces, and hydraulic gradients. 

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