Retentive force factor

From the experimental results shown in Figure 6.6, the retentive force factors (k) which best fitted Equation (6.7) were obtained for both hydrophilic and superhydrophilic surfaces. They were 2.1 and 0.4 for the hydrophilic and the superhydrophilic surfaces, respectively. Using these k values in Equation (6.7), Figure 6.7 shows the adhesion forces of bubbles with varying volumes on the superhydrophilic surface, as compared to a hydrophilic surface. As can be expected from Figures 6.6a and 6.6c, the adhesion force of a bubble on the superhydrophilic surface is much lower than that on the hydrophilic surface due to the significantly lower contact width and... 

The impact of different surface finishes on press fit connectors is another factor to be considered when selecting PWB surface finishes for products such as backplanes. The plastic deformation of the Sn plating, the hardness of the surface finishes, along with the dimensional tolerances of the pin and through-holes, the design of the connector pins (and their mechanical compliance), and the mechanical properties of the PWB, all affect the insertion force required (and consequently the retention force) for the press fit connectors. Typically, the difference in the insertion force among the different surface finishes (Ni/Au, TAg, I-Sn) is not significant (<10%). 

Resilience of textile fabrics when compressed in the bent state is related to wrinkle resistance and retention of shape, drape, and hand. Resilience is an important parameter for evaluating blankets, wearing apparel in which warmth is a factor, pUe fabrics including carpets, and bulk fiber utilization in mattresses, cushions, etc. The general method for determining compressional resilience is to compress and unload the material cycHcahy, creating a plot of compressive force versus fabric thickness. 

The basic operations in dust collection by any device are (1) separation of the gas-borne particles from the gas stream by deposition on a collecting surface (2) retention of the deposit on the surface and (3) removal of the deposit from the surface for recovery or disposal. The separation step requires (1) application of a force that produces a differential motion of a particle relative to the gas and (2) a gas retention time sufficient for the particle to migrate to the coUecting surface. The principal mechanisms of aerosol deposition that are apphed in dust collectors are (1) gravitational deposition, (2) flow-line interception, (3) inertial deposition, (4) diffusional deposition, and (5) electrostatic deposition. Thermal deposition is only a minor factor in practical dust-collectiou equipment because the thermophoretic force is small. Table 17-2 lists these six mechanisms and presents the characteristic... 

The simplest mode of IGC is the infinite dilution mode , effected when the adsorbing species is present at very low concentration in a non-adsorbing carrier gas. Under such conditions, the adsorption may be assumed to be sub-monolayer, and if one assumes in addition that the surface is energetically homogeneous with respect to the adsorption (often an acceptable assumption for dispersion-force-only adsorbates), the isotherm will be linear (Henry s Law), i.e. the amount adsorbed will be linearly dependent on the partial saturation of the gas. The proportionality factor is the adsorption equilibrium constant, which is the ratio of the volume of gas adsorbed per unit area of solid to its relative saturation in the carrier. The quantity measured experimentally is the relative retention volume, Vn, for a gas sample injected into the column. It is the volume of carrier gas required to completely elute the sample, relative to the amount required to elute a non-adsorbing probe, i.e. 

The retention of the band or peak beyond what V0 predicts depends on the magnitude of the equilibrium constant and logically on the volume Vs or area As of the stationary phase. The equation of importance is Vr — V0+KVS and the net retention V/ = KVS. Two main factors influence the value of the equilibrium constant and these are the chemical nature of the mobile and stationary phases. Chemistry is molecules and while true thermodynamics knows no molecules or forces between molecules, chemists think in terms of molecular properties. Among those properties, there is a consideration of the kinds of forces that exist between molecules. Granted that thermodynamics are energy not force considerations but it is useful to understand the main forces involved in the interaction between molecules. Put another way,... 

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