Specific electrical resistivity water

It has also been reported that polypropylene modified with nanosized silicon oxide can distinctively improve the processability of polypropylene while simultaneously increasing its strength. On the basis of the four property indices, specific electrical resistance, water absorption, flex stiffness, and rigidity, the modified fiber has reached or surpassed the indices of polyamide 6. 

The specific electrical resistance of concrete can be measured by the method described in Section 3.5. Its value depends on the water/cement value, the type of cement (blast furnace, portland cement), the cement content, additives (flue ash), additional materials (polymers), the moisture content, salt content (chloride), the temperature and the age of the concrete. Comparisons are only meaningful for the... 

In this equation, R is the specific electrical resistivity for the whole system composed of sediment and pore water, and Rf denotes the electrical resistivity for pore water only. Since the electric cur-... 

The salinity may be determined directly as a total content of water-soluble salts, or as a sum of contents of particular ions. The measurement of the specific electric resistance of the soil is a very rough, but simple and rapid method. It is used for soil surveys on a wide scale. For achieving more precise results, it is possible to use a method standardized by measuring the resistance in saturated soil paste (the soil paste is prepared by mixing a soil sample with distilled water to obtain a moderately liquefied paste) and the results are corrected with respect to a temperature of 16°C. Tables are used to convert the measured electrical resistance values to the soil concentration. For more precise data, it is possible to separate the solution from the saturated soil paste and to measure the specific electric conductivity. The solution separated from the soil paste is called the saturated soil extract. 

Figure 5.3 Effect of water on the specific electrical resistance and the adhesion strength (steel 3-steel 3) of the adhesive based on macrophenylmethane diisocyanate (a), and on macrodiisocyanates made of POPG-1000 and diphenylmethadiisocyanate (b), POPG-2000 and TDI (c), and POPG-1000 and TDI (d) containing 0.2% catalyst and 10% filler (b, A c d), and without filler (b, B) (1) adhesive 0.25 mm thick applied to steel foil (2) electrode in the bulk adhesive (3) electrode on the substrate-adhesive boundary (4) pull-off adhesion strength.

The water resistance of polyurethane adhesive depends to a great extent on the molecular weight of the initial polyester (Fig. 5.3c, d). As this increases, the electrical resistance and water resistance of the adhesive decrease. This is displayed most clearly when the water penetrates along the adhesive-steel boundary. Similar (3 X 10 D cm) specific electrical resistance was obtained with the polyurethane adhesive based on POPG-1000 for 4 days, and with the polyurethane adhesive based on POPG-2000 for 1 day. 

Let us consider a particular example of the effect of RS substances on the water resistance of adhesive-bonded joints. Adhesives based on imsaturated polyester resins, such as PN-1, are distinguished by low water resistance. The influence of water on a steel joint cemented by such an adhesive actually results in some initial increase of the specific electrical resistance along the adhesive-steel interface and then in an abrupt drop (Fig. 5.5). The increase is explained by more complete consumption of the monomer in the system. When ATG is added to the adhesive (which decreases the interphase tension) the specific electrical resistance stabilizes after a drop. The decrease seems to be related to the processes of relaxation of the internal stresses in the adhesive interlayer. The stresses facilitate the diffusion of liquids in polymeric materials, in particular the stress concentration at the polymer-metal interface. 

Figure 5.5 Dependence of the specific electrical resistance at the polyester adhesive-steel interface on the holding time of the joint in water (1) initial adhesive (2) with addition of 10% ATG.

Among the pore fluids, water is the only effective conductor. In many cases, the ionic conduction of the pore water is the dominant conduction mechanism in a porous or fractured rock, and the specific electrical resistivity is controlled mainly by ... 

FIGURE 8.4 Mean value ranges and tendencies for specific electrical resistivity and dielectric permittivity the arrow indicates the effect of water-filled pores and fractures. 

Specific Electrical Resistivity of Dense Rocks, Rocks Without Water Content... 

In an early paper. Brace et al. (1965) published results of a study about the influence of crack and intergramdar porosity and the effect of pressure upon the electrical resistivity of water-saturated igneous rocks. For seven rock samples from Brace et al. s (1965) paper. Fig. 8.8 shows the specific electrical resistivity of water-saturated rocks as a function of pressure. Obviously, there is a strong increase of the resistivity in the range below 400 MPa. This is caused by the reduction in the porosity, mainly by the decrease of the crack-cross section and the closure of crack parts. 

FIGURE 8.8 Specific electrical resistivity versus pressure for water-saturated igneous rocks. After data and figures from Brace et al. (1965). 

In his historical 1942 paper about electrical conduction in clean sands, Archie (see also the historical review in the paper of Thomas, 1992) suggested that the conductivity of the brine-saturated rock is proportional to brine conductivity and that the specific resistivity of the water-saturated rock Rq is proportional to the specific electrical resistivity of the brine... 

Implementing tortuosity x and porosity 4> of the model gives the specific electrical resistivity of the water-saturated rock model ... 

The specific electrical conductivity of dry coals is very low, specific resistance 10 ° - ohm-cm, although it increases with rank. Coal has semiconducting properties. The conductivity tends to increase exponentially with increasing temperatures (4,6). As coals are heated to above ca 600°C the conductivity rises especially rapidly owing to rearrangements in the carbon stmcture, although thermal decomposition contributes somewhat below this temperature. Moisture increases conductivity of coal samples through the water film. 

Grayish-white cubic crystals lustrous and brittle density 5.323 g/cm hardness 6.0 Mohs melts at 938.2°C vaporizes at 2,833°C a poor conductor of electricity electrical resistivity 47 microhm-cm dielectric constant 15.7 specific magnetic susceptibility (at 20°C) 0.122x10 insoluble in water, dilute acids and dilute alkalies attacked by concentrated nitric and sulfuric acids, aqua regia and fused alkalies. 

Metallic appearance in massive form, black to metallic color in powdered state or in electrodeposited form hexagonal crystal system density 20.53 g/cm3 hardness (Brinell) 250 melts at 3,180°C vaporizes at 5,627°C (estimated) vapor pressure 4.6x10- torr at 2,500°C electrical resistivity 19.14 microhm -cm modulus of elasticity 67x10 psi at 20°C specific magnetic susceptibility 0.369x10 thermal neutron absorption cross section 86 barns/atom superconductivity transition temperature 1.7°K insoluble in water and hydrochloric acid soluble in dilute nitric acid and hydrogen peroxide slightly soluble in sulfuric acid. 

Investigation has also been made of the viscosity,5 vapour pressure, boiling-point, specific heat, heat of solution in water,6 electrical resistance... 

The effective solute (ts) transport number, ranged from 93% to 98%, even if reduced to 88% for sodium lactate. The water transport number (tw) increased from 9.3 to 15.6 and correspondently the maximum salt weight concentration in the concentrated stream (CBc,max) ranged from 286 to 350 kg/m3. Finally, while the surface resistance (rc) of the cation-exchange membranes was found to be about constant (5 2fl cm2), ra tended to increase with A/b. However, the specific electric energy consumption (e) slightly increased from 0.19 to 0.22 kWh/kg of salt recovered. 

Effect of the salt molecular mass (MB) on the cation transport number (C) in the corresponding solution effective solute (tB) and water (%) transport numbers surface resistances (rc, ra) of, and counterion transport numbers (tc+, ta ) in cation- and anion-exchange membranes specific electric energy consumption (e) in the case of 90% salt recovery at 1 A, and maximum solute concentration theoretically achievable in the concentrating stream (CBCmax). Note NaCl, sodium chloride Na-A, acetate Na-P, propionate Na-L, lactate. 

Specifically speaking, membrane conductivity represents only the membrane s resistance to flow of protons (H+) and is highly dependant on its thickness (cp) and water content. Electrical resistance of electrodes, cell interconnects, and the formation of any insulating layer on the electrode surface are all bundled under the conductivity term. Voltage decreases for a given current as temperature increases and can be controlled to improve stack efficiency. 

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