Contact angles surface energies measured

The simplest technique introduced by Young as early as 1805 [18] is the measurement of the contact angle as a measure of surface tension and surface energy [1,19, 20,21], In many cases this gives an indication of surface composition and can be used to observe changes in composition, structure and/or roughness at the surface during a particular surface treatment. A quantitative description or distinction between different parameters is hardly possible in most cases. 

It was demonstrated with surface analysis techniques that the polymer surface is modified selectively with different laser irradiation wavelengths. The two laser energy regimes, above and below the threshold for laser ablation, reveal pronounced differences. For both irradiation wavelengths (248 and 308 nm) the polymer surface modification is solely chemical after treatment with fluences below the threshold. Each irradiation wavelength leads to a surface oxidation, as shown with the contact angle and XPS measurements. The oxidation is a result of the radical pathway of photodecomposition of the triazene chromophore. 

Owing to the method of contact-angle or surface-energy measurement, the surface of wool necessarily includes the region between cuticle cells in addition to the cuticle itself Horr has further suggested that vapor adsorption due to capillary condensation may occur at the fiber cuticle scale edges, and that the phenomenon may contribute to the above interpretation that the wool surface is not entirely methyl. Horr also found that the possible composition of the wool fiber surface may even vary depending on the liquid with which it is in contact (e.g., water or methylene iodide). 

The effect of corona discharge treatment on the surface physico-chemistry of PP and PET films has been investigated using surface energy measurements from contact angles, XPS and AFM. The information gathered from these techniques, in addition to practical adhesion measurements, has enabled identification of the dominant mechanisms of adhesion of silicones to these plastic films. The physisorption mechanism and the mechanism of mechanical interlocking are not the cause of... 

Eq. 12 is developed for liquid adsorption on solid, although the molecules adsorbed at infinite dilution do not form an adsorbed liquid film. Schultz et al. demonstrated the validity of this equation, and of the assumptions made, under certain conditions, by comparing the surface energy measured by contact angle method with that determined by gas-solid adsorption on solid surfaces the dispersive component of the surface energy of the liquid equals the surface tension of the alkane probe at the same temperature, i.e., Tl = 7h represents the surface... 

Water was chosen as a polar, and di-iodomethane as a non-polar liquid to compare the surface properties of the hybrid polymer layers containing different commercially available long chain perfluoroalkyl silanes (1 mol% each) with those of other surfaces. The measured contact angles and the surface energy data of the solids calculated according to the Owens and Wendt equation [24] are given in Table 6.3. The increase in the contact angles as a measure for a clearly reduced wettability can be observed with both test substances. 

In Table 3.2, these approaches are applied to our systems methylated solid surfaces and four characteristic nonpolar liquids. The adhesion energy Wvalues are estimated as mentioned above W=Gs + (Jl- F/2. W values are independently obtained data on the work of adhesion for considered nonpolar phases on the basis of contact angle of wetting measurements [20, 34] as W = 0l(1 + cos i ) 0 evaluations of interfacial energy in these systems as 05 = 0s—<7lCosi3. W a) and W(p), 0sl(A) and 0sl(F) are the estimations calculated for the same systems following Antonov and Fowkes, respectively, with the same 0s and 0l. 

The basic phenomenon involved is that particles of ore are carried upward and held in the froth by virtue of their being attached to an air bubble, as illustrated in the inset to Fig. XIII-4. Consider, for example, the gravity-free situation indicated in Fig. XIII-5 for the case of a spherical particle. The particle may be entirely in phase A or entirely in phase B. Alternatively, it may be located in the interface, in which case both 7sa nnd 7sb contribute to the total surface free energy of the system. Also, however, some liquid-liquid interface has been eliminated. It may be shown (see Problem XIII-12) that if there is a finite contact angle, 0sab> the stable position of the particle is at the interface, as shown in Fig. XIII-5Z>. Actual measured detachment forces are in the range of 5 to 20 dyn [60]. 

Surfa.ce Energy. The surface energies of Parylenes N, C, and D were measured by observing the contact angles for several standard probe hquids. AH three have surface energies of approximately 45 mj/m (= dyn/cm), ie, all test Hquids having less than 45 mj/m surface tension completely wet the as-deposited parylene surfaces (43). 

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