Surface energy measurement

An example of interaction stiffness and force curves for a Si surface with a native oxide at 60% relative humidity (RH) is shown in Fig. 12 [104]. The stiffness and force data show an adhesive interaction between the tip and substrate. The hysteresis on retraction is due to a real change in contact area from surface oxide deformation and is not an experimental artifact. The adhesive force observed during retraction was consistent with capillary condensation and the surface energy measured from the adhesive force was close to that of water. 

Values of surface energy measured by this technique were found to be 1.140 J/m2 for Ag at 903 °C, 1400J/m2 for Au at 1204 °C, and 1.650 J/m2 for Cu at 1000 °C. The solid-vapor surface energy is relatively independent of the temperature, but the surface energy of a solid-vapor interface depends on its crystallographic orientation, so these measured values must reflect an average value for many orientations. 

When attempting to relate the adhesion force obtained with the SFA to surface energies measured by cleavage, several problems occur. First, in cleavage experiments the two split layers have a precisely defined orientation with respect to each other. In the SFA the orientation is arbitrary. Second, surface deformations become important. The reason is that the surfaces attract each other, deform, and adhere in order to reduce the total surface tension. This is opposed by the stiffness of the material. The net effect is always a finite contact area. Depending on the elasticity and geometry this effect can be described by the JKR 65 or the DMT 1661 model. Theoretically, the pull-off force F between two ideally elastic cylinders is related to the surface tension of the solid and the radius of curvature by... 

Fig. 4 The components of the surface energy measured on hydrogenated carbon overcoated thin film magnetic recording media (A) The dispersive component of the surface energy for PFPE Z and Zdol (B) the polar component of the surface energy for PFPE Zdol with molecular weight (M-w) of 1100 (A) 1600 (O), and 3100 ( ) g/mol and (C) the disjoining pressure as a function of film thickness for PFPE Zdol (Mw is 3100 g/mol).

In summary, through the use of a simple type of XPS(0), the molecular orientation at the surface of sulfonated PS films has been determined. In the more sulfonated films the sulfur and oxygen atoms reside preferentially below the surface, as their respective XPS(6) core-level signals decrease with increasing 0 faster than the matrix C(l ) signal. These results are corroborated by surface energy measurements that also indicate that the accessibility of the sulfonate groups depends on associative interactions in the solid. In particular, it appears that a preferential... 

Elastomer reinforcement by carbon black is generally considered as the consequence of the adsorption of polymeric chains onto carbon black surface. Therefore carbon black surface energy knowledge is of primary importance in carbon black characterization. However, very few carbon black surface energy measurements have been published this can be easily understood considering the difficulty of such measurements on a highly heterogeneous and tortuous surface. 

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). 

Clark, A. The Theory of Adsorption and Catalysis. New York Academic Press, 1970. Hondros, E.D., "Surface Energy Measurements", in Physicochemical Measurements in Metals Research. Techniques of Metals Research IV, Part 2. Rapp, R.A. (ed.). New Yoik ... 

The first verification of the fundamental equations of Gibbs and Lippmann was based on surface tension (surface energy) measurements. The investigation of solid electrodes with this method is restricted. In the following paragraph a description is given of some of the modem methods, which are used for investigation of the electrochemical double layer. 

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... 

The level of discharge treatment used in this study is quite high, but not by any standards excessive. (Experimental details can be found in Ref. 7.) It corresponds to the level of maximum autohesion under the heatsealing conditions employed in this study (Fig. 3). It also corresponds to a level at which the film used would pass a searching printability test. The surface energy measured... 

The first three chapters discuss definitions, adhesion theories, surface characterization and analysis, surface energy measurement methods, adhesion mechanism, failure modes, and surface treatment of materials. 

Chan, D., Hozbor,M.A., Bayramh, E. and Powell, R.E.(1991), Surface Characterization of Intermediate Modulus Graphite Fibers via Surface Energy Measurements and ESCA , Carbon 29(8), p.l091. 

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... 

Even in the case of single crystal or glass there is a slight discrepancy between the surface energy measured by vaporisation and the crack resistance, owing to the dissipation unavoidably associated to mechanical fracture. 

G. K. Bansal and W. H. Duckworth, Fracture Surface Energy Measurements by the Notched Beam Technique, in Fracture Mechanics Applied to Brittle Materials, ASTM STP 678, ed. S. W. Freitnan, (ASTM, Philadelphia, PA, 1979), pp. 38 46. 

Particle surface modification could be characterized with the surface energy measurement, ilow the surface energy of dispersed particle affects the ER efiect was systematically addressed by Hao [95]. A set of oxidized polyacrylonitrile (OP) materials of different surface properties were employed for such a purpose. The five kinds of water-free ER fluids composed of oxidized polyacrylonitriles (OP) particle dispersed in a low viscosity silicone oil were used for correlating the ER effect with the particle surface energy. The powdered OP materials with average particle size 0.1-10 pm were treated at 150 C for 8 h, and then dispersed in silicone oil immediately at the particle volume fraction of 35 vol /o. The surface energy was measured by means of the dynamic wicking method [96]. Water and... 

Liquid vs Solid Surface Energy Measurement Techniques... 

Fig. 11 Overall and polar surface energies measured by the Owens-Wendt technique (with Washburn absorption) for various types of Toray TGP-H paper GDLs. Values in white boxes represent the total aerial loading of PTFE for each sample. AA plain, BA 5 wt% substrate/0 wt% MPL, BC 10 5wt% substrate/10wt% MPL, BC 5wt% substrate/23wt% MPL, DA 20wt% substrate/0 wt% MPL, DC 10 20wt% substrate/10wt% MPL, DC 20wt% substrate/23 wt% MPL...

---