Stickiness parameter

FIGURE 7.10 Pseudo-binary phase diagram of the water, HNO3/DMDBTDMA, dodecane system to identify the third-phase limit. Experimental points (circles) and theory (lines) obtained from Baxter sticky hard-sphere approach. The theoretical line is obtained with the experimental determination of the linear variation of the stickiness parameter tt1 versus [HN03]/[DMDBTDMA]. The different lines illustrate the impact of the error in this T-1 experimental linear law. (From C. Erlinger, L. Belloni, T. Zemb, and C. Madic, Langmuir, 15 2290-2300, 1999. With permission). 

As can be seen from the results the values of X are usually close to two. In general, they are higher for the protic solvents than the aprotic ones. The stickiness parameter is negative for aprotic solvents and positive for most protic solvents. A negative value of Iq indicates that the degree of order in the solvent is higher than one predicts on the basis of the simple point dipole-dipole model. It also reflects the fact that the dipole moment is not centrally located in the solvent molecules considered. 

Solvent Polarization Parameter ks Stickiness Parameter h Molecular Polarizability lO otp/nm Kirkwood Correlation Parameter... 

Fig. 4.4 Plot of the stickiness parameter to against the values of fip /(eod ), which characterizes the strength of dipole-dipole interactions for two selected solvent groups.

Adhesiveness, defined as the work necessary to overcome the attractive forces between the surface of the sample and the surface of other materials with which the food comes into contact, e.g. tongue, teeth, palate, etc. (Szczesniak, 1963), is given on the texturometer curve by the negative force area, representing the work needed to pull out the plunger from the sample. This parameter s value may be considered an evaluation of stickiness of jelly. Fracturability, also called brittleness, is given by the measure (%) of the plunger path into the jelly when it breaks. 

Two important morphological parameters characterizing ball-milled powders are the particle and grain size of constituent phases within the powders. In our laboratory, the size measurement of the powder particles is carried out by attaching loose powder to sticky carbon tape and taking pictures under secondary electron (SE) mode in the SEM. The images are then analyzed by an image analysis software. The size of the powders is calculated as the particle equivalent circle diameter, ECD = AA/nf, where A represents the projected particle area. Usually from -300 to 700 particles are analyzed for each batch. 

If the substrate is also sticky k2 ks), we arrive at the diffusion-controlled parameter ki... 

The capture efficiency of sticky surfaces for dry particles, and of dry surfaces for moist or sticky particles (ascospores or dye particles), agrees reasonably with theory, but dry surfaces are less efficient for dry particles. Theory and experiments on filter efficiency (Dahneke, 1971 Esmen et al., 1978 Ellenbecker et al., 1980) have shown that the critical parameter is the kinetic energy of the particle. Figure 6.4 shows Cp/C, as given by the ratio of catch on non-sticky compared with sticky pine needles (Chamberlain Little, 1980). Also shown are the results of experiments by Ellenbecker et al. (1980) (0.2-//m fly ash particles on 8-fim steel fibres) and Aylor Ferrandino (1985) (Lycopodium particles... 

The many different types of adhesives and the wide variety of ways in which they can be used influence the potential for migration of chemicals into the packaged food. This then helps to provide a framework for subsequent considerations of specific applications. The two main parameters considered are the surface area of adhesive used and the residual content of low molecular weight substances. Taking surface area first, there clearly is a quantitative difference between small spots or strips of adhesive used at ends and seams to fabricate cartons and pouches or used to attach small sticky labels, compared to an adhesive used to glue whole sheets of materials together to make a laminate. As regards composition, for solvent-based, water-based heatseal... 

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