Solid compressibility

The compressibility of solids is the fractional change in volume per unit pressure change and is expressed as 

The line from the origin to point A is the compressibility curve. It is from this line and not from the abscissa that intruded volumes are measured. Similarly, the line from point B to the ordinate is the decompression curve from which the extruded volumes are measured. The assumptions made when using this method for correcting intrusion-extrusion curves for compressibilities are  

That occluded pores or bubbles in the sample are also elastic and restore to their initial condition after decompression. 

That the compressibility is constant over the entire pressure range. In fact, solid compressibilities are slightly nonlinear, decreasing with increasing pressure. 

---

CA 45, 2885(195lXHydrogenati°n of nitrocompds with Raney Ni treated with chloroplatinic acid and with alkali) p)J.A.Grand R.Miller, USP 2555333(1951) CA 45, 7337(1951XUse of Cu chromite as combustion catalyst in solid compressed fuel, such as mixt of NGu 75 GuN 25%) r)Anon, ChemEngrg 1951, June, p 183 (Catalytic process for waste disposal developed by D.V.Moses and put into operation at DuPont s Belle Plant, West Virginia, consists of vapor -phase catalytic destruction of organic wastes by oxidation to C02 H20. It was claimed that the method is more convenient than bio-oxidation... 

The stress-strain data can be generated from either tension or from compression tests. For soft solids, compression tests are preferred since it avoids the need to clamp the sample ends. Consequently, compression tests are widely used in testing foods. However, the friction between the loading plates can be significant, as noted by several investigators (58-61). 

Fig. 4.11 A column of particulate solids compressed between two pistons in a channel with a constant cross section. A force F0 is applied at x = 0, which is balanced by a force FL at x = L. The column is either moving at constant velocity or is stationary. The upper plate is either stationary or is moving with constant velocity.

Hexamine is a white, crystalline solid compressed into small tablets. It is made by eva porating a mixtu re of formalin solution and laundry ammonia. Fairly half-hearted attempts to produce it at home were unsuccessful. No doubt hexamine could be home-made, but, at this time, it was too much bother and expense. 

Boyle s law (L oc 1/P). A change in gas pressure in one direction causes a change in gas volume in the other. What happens to the particles when external pressure compresses the gas volume And why aren t liquids and solids compressible ... 

In a solid, the attractions dominate the motion so much that the particles remain in position relative to one another, jiggling in place. With the positions of the particles fixed, a solid has a specific shape and does not flow significantly. The particles are usually slightly closer together than in a liquid, so solids compress even less than liquids. 

The two second-order equations (58) and (59) yield four solutions for to. The first solution is a seismic wave in which the fluid and solid compress almost in phase. However, since the fluid is normally an order of magnitude more compressible than the solid, fluid flow is induced and the shear and bulk viscosities give rise to attenuation. This attenuation is minor for low frequency waves and much greater for high frequency waves. 

The drag that is imposed on each particle is transmitted to adjacent particles. Therefore, the net solid compressive pressure increases as the filter plate is approached, resulting in a decrease in porosity. Referring to Figure 4A, it may be... 

Lu W.M., Huang Y.P. and Hwang K.J., 1998b. Methods to determine the relationship between cake properties and solid compressive pressure, Separ. Purif. Tecfmol., 13, 9-23. 

The compressibility of cakes, i.e. the increasing resistance of cakes with pressure, can be tested in various ways. As was briefly mentioned in section 9.2.2, one way of testing the relationship a =/(Apc) is in the compression-permeability cell. The solids compression is created by the mechanical action of the piston—an obvious assumption made is that hydraulic pressime can be simulated by mechanical compression. 

Figure 12. The hard-sphere equation-of-state (d = 3.9 A) as a function of reduced fluid density computed for polyethylene at T = 430 K and N = 6429 by various thermodynamic routes free energy (upper solid), compressibility (lower solid), wall (dashed), and GFD (short/long dash). The inset includes attractions by perturbation theory using the GFD curve as the reference system the points represent experimental results. ...

In a dead-end membrane filtration process, the number of particles instantaneously arriving at the surface of membrane or a formed fouling layer is mainly controlled by the filtration rate and slurry concentration, while the packing structure of the particles depends on their size, shape, physical and chemical properties and so forth. Since the solid compressive loading on a thin layer of the cake surface is limited, the porosity of the surface cake layer, e (that is Si i, 2,2 and ii in Figure 15.6), during a membrane filtration process can be assumed to be a constant value and can be preliminarily estimated by a low-head filtration experimental system proposed by Haynes [41]. 

Fouling layers, in general, are compressible, that is they become more compact as the extent of their compression increases. Solid compressive pressure is responsible for the compression of a fouling layer according to basic filtration theory [46]. In traditional filtration theory, the derivation of the drag equations of filtration for rigid particle slurries assume that particles are in point contact mode and that compression attends instantaneously. Under this assumption, a force balance can be obtained between liquid pressure over the entire cross-section and the solid compressive pressure on the total mass within the porous layer as ... 

Figure 15.10 Porosity as a function of solid compressive pressure in the fouling layer formed in the dead-end microfiltration under AP — 6 kPa for 0.5% cross-linked S. cerevisiae suspension.

---