A new interfacial film balance is described. The instrument permits rigorous cleaning of the interface and compression of a spread monolayer. Film pressurelarea relations for spread monolayers of sodium octadecyl sulphate, octadecyl and docosyl trimethylammonium bromides and an equimolecular mixture of sodium octadecyl sulphate and octadecyl trimethylammonium bromide are given for the interface between n-heptane and aqueous NaCl solutions at 20°C. The phase transition observed in the mixed monolayers is accounted for in terms of a simple discrete-charge model.
The dispersion and polar components of the surface free energy of untreated and chlorinated Lincoln wool fibers have been determined from the wetting forces of water and methylene iodide. The values obtained for the untreated wool fibers were close to those previously reported for human hair. Chlorination increased only the polar component. The three-phase boundary moved in steps corresponding to the scale spacing of the fiber surface. Procedures for determining relevant wetting forces were developed. The surface energy of wool is an important factor in the wet processing of wool and in the performance of the finished garment. In shrinkproofing wool by polymer deposition, surface thermodynamics may control the spreading of the polymer on the fiber surface and affect the subsequent adhesion of the polymer to the fiber [ 14]. Previous workers [2,7,14,26,30] have characterized the surface of the wool fiber by determining the critical surface tension (CST): this is the value of the surface tension of a wetting liquid at which the contact angle becomes zero .Certain chemical treatments of wool, such as chlorination, have been found to increase the CST.Feldtman and McPhee [ 14] proposed that the condition for spontaneous spreading of a liquid polymer on a fiber was that the fiber must have a higher CST than the polymer. Such treatments as chlorination did indeed increase the CST of the fiber and also resulted in a dramatic improvement in the shrinkproofing efficacy of the subsequent polymer application [ 14]. Although this effect was consistent with the theory, there are alternative mechanisms by which such treatments may improve the distribution and adhesion of a polymer. These mechanisms include the increased probability of chemical interactions between the polymer and the treated wool [ 13], the generation of anionic groups in the wool [ 13], and increased diffusion of polymer into the fiber [6,29]. At present, it is not clear to what extent changes in the surface energy of the wool affect the application of various polymers. The CST is not normally equal to the surface energy of the solid; if it were, the interfacial energy between the solid and the wetting liquids used in the test would have to be zero. In general, this condition is not met, and equations have been proposed expressing the interfacial energy in terms of the dispersion (ysj and polar (-ysP) components of the surface energies (ys) of the two phases [ 17, 24, 31 ]. Owens and Wendt developed a method to determine these components for any solid from measurements of the contact angles of a pair of pure liquids on the solid . At present there are two alternative equations that can be used: the extended Fowkes' equation and Wu's equation. The form and use of these equations has been adequately presented in the literature [27, 32]. The optimum condition for spreading and adhesion is when the values of 'Y? and ys for the adhesive are equal to the values for the adherend . In our laboratory, contact angles for each fiber were calculated from meas...
Relationships have been determined between film pressure and bulk concentration for dodecyl trimethylammonium bromide and for sodium dodecyl sulphate in a n-heptane/O.l M aqueous sodium chloride system at 20°C. The results obtained by ineans of the dipping-plate technique conflict with previously reported results from drop-volume measurements. Relationships between film pressure and area per molecule for adsorbed monolayers were derived by means of the Gibbs equation. Excellent agreement was found for the force-area relations of spread and adsorbed films of the same head-group, confirming the earlier finding that these relations are independent of chain length. The insoluble-monolayer technique thus provides an accurate criterion of the reliability of interfacial tension-concentration data for soluble films.
The role of capillarity in improving the cohesion and tensile properties of oiled yam is discussed and experimentally tested. The effect is significant for low twist Sirospun yam and results in a lower rate of warp breaks than with a wax lubricant.Because of increasing labor and machinery costs, weavers are tending to regard high efficiencies, high weft insertion rates, and nominal mending as obligatory for all fibers. This has resulted in an increasing reluctance to weave some finer woolen and worsted yams.The finer, cooler fabrics demanded by today's fashions and lifestyles often depend on the unique properties of Sirospun yam [ 5 ], and so the weaving characteristics of this yarn are of particular interest.
In experiments with a thin bed of cloth, the maximum rate of uptake of dye by a wool yarn has been found to be limited by the concentration gradient of the dye across the yarn. A type of unlevelness observed in a conventional cross‐wound package is attributed to the same concentration gradient.
Exponential exhaustion curves were found experimentally to give more level uptake of dyes on wool than linear exhaustions or recommended temperature‐time procedures taking the same time. This conflicts with predictions from ‘significant dyeing rate’ theory.
A melting-point calorimeter has been constructed for a rapid (3-4 hr.) determination of the purity of a 3 ml. sample by measurement of the solidliquid equilibrium temperature as a function of the fraction which is liquid. The heat of fusion is determined to about f 10% and the molar percentage of impurity to about f20%. Melting points, heats of fusion, and purities are given for diverse samples of m. p. -140" to -14".
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