Owens-Wendt method

Contact Angle Measurements, were obtained with a Drop Shape Analysis System DSA100 (Kriiss GmbH, Hamburg, Germany) using water and diiodomethane as test liquids. The contact angles were measured by the sessile drop method within two seconds. The surface tension y as well as the dispersive and polar components (yD and yp) were calculated based on the Owens-Wendt method [7],... 

Table 12.1 Contact angle (sessile drop) and surface energy of several hydrophilic polymers (calculated by the Owens Wendt method).

Surface free energy Owens-Wendt method Banana stem and bunch 26... 

Miyata and Yamaoka [26] used scanning probe microscopy (SPM) to determine the micro-scale friction force of a silicone-treated polymer film surface. PU acrylates cured by an electron beam were used as the polymer films. The micro-scale friction force obtained by SPM was compared with macro-scale data, such as surface free energy determined by the Owens-Wendt method and the macro-scale friction coefficient determined by the ASTM D1894 method [27]. These comparisons showed that a good linear relationship existed between the surface free energy and the friction force, which was insensitive to the nature of the polymer specimens or to the silicone... 

Table 1 Surface energies (by the Owens-Wendt method) of two different SIGRACET gas diffusion layer (GDL) types before and after accelerated durability testing (different catalyst-coated membranes were used in the cells)...

Table 15.3 shows components of surface tension for some solid polymers estimated by the Owens-Wendt methods the Zisman critical surface tensions values are also given. There is rather good agreement between the predicted polymer surface tensions from the Owens-Wendt and Zisman methods. 

Example 15.1. Effect of contact angle measurements on the determination of solid surface tensions using the Owens-Wendt method. Based on data by Owens and Wendt (1969). 

The Owens-Wendt method for the interfacial tension combined with the Young equation for the contact angle is given by (assuming zero spreading pressure) ... 

Compare the results of questions (1) and (2) with each other and with the results of the Owens-Wendt method (Problem 15.1) and the van Oss-Good approach. 

Gurau et al. [194] proposed a method to estimate the internal contact angle to water by combining the Washburn technique with the Owens-Wendt... 

These properties are listed in order of usefulness for comparative review purposes. Liquid surface tension is the most fundamental property, because it pertains only to the material in question (provided the material is adequately pure) and the technique used for measurement. All the other properties listed are dependent also on solvents, contact-angle test liquids, and liquid or solid substrates selected. For solids, approaches such as the Owens-Wendt analysis (7) have supplanted the Zisman method (18) in recent years, but data from the Zisman method for organosilicon polymers are more available compared with data from the Owens-Wendt approach. Some useful data on aqueous surface tensions and Langmuir troughs are also available. Data for other listed properties are of less fundamental use and rather scanty. 

The surface energy (y) was calculated by using the method of Owens, Wendt, Rabel and Kaelble. The initial value of the contact angle, the polar (y ) and dispersive (y ) terms of the surface energies have been calculated by the instrument software. 

Table 3 Surface energies calculated by Owens, Wendt, Rabel and Kaelble method for both MDF...

Contact angles of sessile drops were measured using an Advanced Surface Technology video contact angle VCA2500 system. Contact angles were measured on the modified side of the plastic films within 20 min of treatment. The method of calculation used in this study was the geometric mean approach of Owens-Wendt [1] and Kaeble [2]. 

OWENS, WENDT, AND KAELBLE S METHOD (TWO-LIQUID GEOMETRIC METHOD)... 

Differences in the value of adhesion between conventional surfactants and RS are expected. The comparison of conventional anionic, cationic and nonionic surfactants with reactive ones was performed with calculations based on wetting experiments and direct adhesion measurements that reflect the real value of adhesion most directly. The well-known Owens-Wendt [7] and Wu [8] methods were used for calculating the work of adhesion. The calculated and the measured peeling force values are given in Table 1. 

In a large part of the (current) literature the Lifshitz-van der Waals component (o, is simply termed dispersion component and the Lewis acid-base interactions (o ) are interpreted as polar interactions even though the material s dipole moments may be zero or the interactions originating from permanent dipoles are very small and can be easily associated with the dispersion part [6]. The misleading denominations go back to a historical misidentification of the acid-base interactions as polar interactions in the Owens-Wendt-Rabel-Kaelble [7-9] approach to calculate the IFT [6] (OWRK model). However, as an impact on the SFE calculation by this misinterpretation of this old theory occurs only when a monopolar base interacts with a monopolar acid, this nomenclature is still widely used. And here in this work we will also use the terms dispersion and po/ar interactions to differentiate the two major contributions to SFE, ST, and IFT. For a detailed discussion of the use of contact angles in determining SFE of solids and other methods of determining SFE, see Etzler [10]. 

Effectiveness of plasmochemical modification of the fillers is represented by changes to their surface free energy (SFE) and its components-polar and dispersion one. SFE was examined with a KlOO MKII tensiometer (KRUSS GmbH, Germany). Contact angle was determined using polar (water, methanol, ethanol) and nonpolar (n-hexane, n-heptane) liquids. SFE and its components were calculated by the method proposed by Owens-Wendt-Rabel-Kaeble [9]. 

To do so, we must perform contact angle measurements for different liquids on the same solid. The minimum number of required data depends on the theory. In the case of Owens-Wendt we need data for two liquids on the same solid, while the most advanced theories (Hansen/Beerbower and van Oss-Good) require data for at least three liquids on the same solid. Graphical methods can also be used, e.g. the Owens-Wendt equation can be written in the form ... 

The Hansen method has not been extensively compared with the classical surface component methods. How are the dispersion and polar/hydrogen bonding contributions to surface tension from the Hansen method compared to the corresponding contributions from the Fowkes/Owens-Wendt and van Oss-Good methods Comment on your findings. 

Problem 15.6 The Dann method compared to Owens—Wendt. Based on Dann analysis and data (Dann, 1970). 

Apply the Fowkes and Owens-Wendt equations to these interfaces. What do you conclude on the apphcabUity of these methods for these interfaces ... 

Compare the Fowkes, Owens-Wendt and Harmonic Wu equations for the four polymer mixtures for which experimental data were provided. Which method performs best Provide a short discussion. 

Owens-Wendt-Rabel-Kaelble (OWRK) method. Owens and Wendt [19] modified the Fowkes model by assuming that solid surface tension and liquid surface tensions are composed of two components, namely, a dispersion component and a hydrogenbonding component. The nondispersive interaction was included into the hydrogenbonding component. Nearly at the same time, Rabel [20] and Kaelble [21] also published a very similar equation by partitioning the solid surface tension into dispersion and polar components. Subsequent researchers called this as the OWRK method, and ysv and jiv can be expressed as... 

The wettability of a polymer film normally is determined by static contact angle measurements. The surface free energy (SE) of a polymer can be determined by wettability measurements with two different liquids. The dispersion force and polar contributions to SE, 7 d and 7 p respectively, are also calculated normally by using the Owens and Wendt, and Kaelble methods [146,147], The measurements of contact angles (CA) on a given solid surface is one of the most practical ways to obtain surface free energies. 

If 1 and 2 are immiscible liquids of which y1 and y2 are known, and of which one is apolar (yp = 0), the y-components of both liquids may be derived in the following way. The interfacial tension y22 is measured by one of the available methods and the Eqs. (8.21b) and (8.20) are solved. In this way several liquids have been investigated the values of y 1, yd and yp are given in Table 8.6. Analogous values for polymers are presented in Table 8.7. Owens and Wendt also gave a more general expression for Eq. (8.10) viz. ... 

Surface tension studies of the most common fluorosilicone, poly(3,3,3-trifluoropropylmethylsiloxane) (PTFPMS), give unexpected results. Compared with (PDMS), PTFPMS has a higher liquid surface tension, a similar critical surface tension of wetting, and a considerably lower solid surface tension, as determined by water and methylene iodide contact angles and the method of Owens and Wendt (67). These results are summarized in Table X (7, 67, 72-74, 76, 77), in which PTFPMS is compared with two other fluorocarbon polymers, poly(tetrafluoroethylene) (PTFE) and poly(chlorotrifluoroethylene) (PCTFE). PTFE behaves like PTFPMS, whereas PCTFE behaves like PDMS. 

Geometric-mean approach (Fowkes and later Owens and Wendt s method)... 

Owens and Wendt applied only two liquids to form drops in their experimental surface tension determinations. They used fw = 21.8 and y(v =51.0 for water, and y= 49.5 and y[v = 1.3 mj m 2 for methylene iodide, in their calculations. After measuring the contact angles of these liquid drops on polymers, they solved Equation (693) simultaneously for two unknowns of yfv and y( v, so that it would then be easy to calculate the total surface tension of the polymer from the (ysv = yfv + 7sv) equation. Later, Kaelble extended this approach and applied determinant calculations to determine ysv and y(v- When the amount of contact angle data exceeded the number of equations, a non-linear programming method was introduced by Erbil and Meric in 1988. 

This method utilizes a similar approach to Owens and Wendt s method but uses a harmonic-mean equation to sum the dispersion and polar contributions. Wu reported that the Owens and Wendt equation was giving surface tension values for polymers in error by as much as 50-100% when compared with their melt values, particularly for polar polymers. He suggested that a harmonic (or reciprocal) mean approximation might be better for polar polymers as given ... 

For the values of the surface energies which must be inserted in the Dupre equation, recent surface energy data for the polymers used in this study, which were determined by Erhard (21) could be used. Erhard determined experimentally the surface free energies of the polymers and computed the work of adhesion with the method of Owens and Wendt. Table II shows the data of the work of... 

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