Contact angle measurements and

TABLE II. ANAEROBIC CRUDE OIL ADHESION TENSION MEASUREMENTS AND CONTACT ANGLES USING IFT = 36.4 DYNE/CM... 

Kwok, D.Y., Gietzelt, T., Grundke, K., Jacobasch, H.J., and Neumann, A.W. (1997). Contact angle measurements and contact angle interpretation. 1. Contact angle measurements by axisymmetric drop shape analysis and a goniometer sessile drop technique. Langmuir, 13, 2880-2894. 

D. Li, P. Cheng and A.W. Neumann, Contact Angle Measurement by Axisymmetric Drop Shape Analysis (ADSA), Adv. Colloid Interface Set 39 (1992) 347, and references to the Neumann group in sec. 5.12 D.Y. Kwok, A.W. Neumann, Contact Angle Measurement and Contact Angle Interpretation, Adv. Colloid Interface Set 81 (1999) 167-249. 

Kwok DY, Neumann AW (1999) Contact angle measurement and contact angle interpretation. Adv Colloid Interface Sci 81 167-249... 

Since both sides of Eq. X-39 can be determined experimentally, from heat of immersion measurements on the one hand and contact angle data, on the other hand, a test of the thermodynamic status of Young s equation is possible. A comparison of calorimetric data for n-alkanes [18] with contact angle data [95] is shown in Fig. X-11. The agreement is certainly encouraging. 

Li and Neumann sought an equation of state of interfacial tensions of the form 7 l = /(Tlv. TSv). Based on a series of measurements of contact angles on polymeric surfaces, they revised an older empirical law (see Refs. 216, 217) to produce a numerically robust expression [129, 218]... 

An astronaut team has, as one of its assigned experiments, the measurement of contact angles for several systems (to test the possibility that these may be different in gravity-free space). Discuss some methods that would be appropriate and some that would not be appropriate to use. 

One may also be able to determine the work of adhesion for cases in which the contact angle is zero by using probe liquids, as described later in this chapter. There are also other ways of determining the work of adhesion, such as inverse gas chromatography, which do not depend solely on capillary measurements (surface tension and contact angle). This too will be discussed later. 

Many of the most widely used methods are based on measuring the contact angles of a series of test liquids on the solid surface, and evaluating the surface energies via Young s equation, Eq. 4 above. 

The adsorption of gas onto a solid surface can also be used to estimate surface energy. Both inverse gas chromatography (IGC) and isotherm measurement using the BET method [19] have been used. Further discussion and detailed references are given by Lucic et al. [20] who compare the application of IGC, BET and contact angle methods for characterising the surface energies of stearate-coated calcium carbonate fillers. 

The most widely used techniques for surface analysis are Auger electron spectroscopy (AES), x-ray photoelectron spectroscopy (XPS), secondary ion mass spectroscopy (SIMS), Raman and infrared spectroscopy, and contact angle measurement. Some of these techniques have the ability to determine the composition of the outermost atomic layers, although each technique possesses its own special advantages and disadvantages. 

To investigate the influence of swelhng of the substrate by the contacting liquid, the contact angle 6 of sessile drops of tricresylphosphate, TCP (drop volume 2 p,L, viscosity t = 70 cP, surface tension = 40.9 mN m ), has been measured as a function of time after deposition, t, on flat, smooth, horizontal surfaces of soft and rigid solids at 20°C. The method of measurement of contact angle is the same as in Section Ill.A. 

Most of the sample preparations and contact angle measurements were made by A. D. Karnas. K. W. Littlepage and G. G. Engerholm did the ESCA spectroscopy. J. Burns did the electron microscopy on the block copolymers. I thank D. F. Hager and G. B. Butler for helpful discussions. 

The measured contact angle of mercury on various samples can range from 112 to 170° [39], but for most applications the average value of 140° is used. It should be noted, however, that the accuracy of the pore radii measurement is limited by the accuracy of the contact-angle measurement [40]. Contact angles can readily be measured on flat surfaces or compacts of powders [6], and the measurement of contact angles with powder systems has also been reported [41]. 

Encouraged by the X-ray and contact angle results, we performed some preliminary gas-permeation measurements. Here, a self-supporting film is required and only the longer block copolymers were used. Fluoro-PSB-II and Fluoro-triblock were coated on porous Celgard 2400 membranes the measurements were taken at room temperature at a driving pressure of 5 bars. Since no absolute polymer layer thickness has been determined, only relative values of the permeability are given (Table 10.6). In the case of the separation of C02 from... 

Relation between bacterial adhesion to sulphated polystyrene (A) and cell surface characteristics as determined by electrophoretic mobility and contact angle measurement. Results were obtained by interpolating the data points for the adhesion of 17 different strains of bacteria. 

Procedures for infrared and ultraviolet absorption and contact angle measurements are reported in the previous publication (11). 

Melting points and contact angle measurements of the fatty acid-DETA reaction products are recorded on Table I. 

---