Contact angle temperature

Substrate Metal/Alloys Contact Angle (°) Temperature (K) Atmosphere Ref. 

This method suffers from two disadvantages. Since it measures 7 or changes in 7 rather than t directly, temperature drifts or adventitious impurities can alter 7 and be mistakenly attributed to changes in film pressure. Second, while ensuring that zero contact angle is seldom a problem in the case of pure liquids, it may be with film-covered surfaces as film material may adsorb on the slide. This problem can be a serious one roughening the plate may help, and some of the literature on techniques is summarized by Gaines [69]. On the other hand, the equipment for the Wilhelmy slide method is simple and inexpensive and can be just as accurate as the film balance described below. 

The effect of temperature on contact angle is seldom very great, as a practical observation. Some values of d0/dTare included in Table X-2 a common figure is about -0.1 degrees/K (but note the case of CS2 on ice also rather large temperature changes may occur in L1-L2-S systems (see Ref. 160). 

There is no reason why the distortion parameter should not contain an entropy as well as an energy component, and one may therefore write 0 = 0q-sT. The entropy of adsorption, relative to bulk liquid, becomes A5fi = sexp(-ca). A critical temperature is now implied, Tc = 0o/s, at which the contact angle goes to zero [151]. For example, Tc was calculated to be 174°C by fitting adsorption and contact angle data for the -octane-PTFE system. 

Values of the contact angle B of mercury at room temperature on various solid surfaces... 

Hard lenses can be defined as plastic lenses that contain no water, have moduli in excess of 5 MPa (500 g/mm ), and have T well above the temperature of the ocular environment. Poly(methyl methacrylate) (PMMA) has excellent optical and mechanical properties and scratch resistance and was the first and only plastic used as a hard lens material before higher oxygen-permeable materials were developed. PMMA lenses also show excellent wetting in the ocular environment even though they are hydrophobic, eg, the contact angle is 66°. 

Thus apolar probe liquids of sufficiently high surface tension to yield finite contact angles against many surfaces are especially valuable for this purpose. Popular examples of these include diiodomethane, with a surface tension of 50.8 mN/m at 23°C, and a-bromonaphthalene, with a surface tension of 44.4 mN/m at the same temperature. One should be cautioned, however, that both are sufficiently volatile that the 7re-effects may not be negligible with their use. 

The effect of thermal aging on polyethylene and isotactic polypropylene have been studied by Konar et al. [49]. They used contact angle, contact angle hysteresis, and XPS to characterize the modified surfaces of the polymers. Hysteresis increased with aging temperature. In the case of polyethylene, thermal aging led to a significant increase in adhesion strength of polyethylene with aluminium, but the increase in the case of polypropylene was much less marked. 

As can be seen in Table 6.5, ONB in APG solution of concentration C = 100 ppm took place at significantly higher surface temperatures. It should be noted that the ONB in surfactant solutions may not be solely associated with static surface tension Sher and Hetsroni (2002). Other parameters such as heat flux, mass flux, kind of surfactant, surface materials, surface treatments, surface roughness, dynamic surface tension and contact angle need to be considered as well. 

In this section the influence of the pressure in the capillary and the heat flux fluctuations on the stability of laminar flow in a heated capillary tube is analyzed. All the estimations performed in the framework of the general approach and developed in the previous section are kept also in the present cases. Below we will assume that the single cause for capillary pressure oscillations is fluctuations of the contact angle due to motion of the meniscus, whereas heat flux oscillations are the result of fluid temperature fluctuations only. 

All data refer to room temperature if not stated otherwise. CA = Contact angle method. See also list of symbols. 

Fig. 21—The thickness and water contact angle of FTE SAMs on the DLC surfaces as a function of the immersing time in a 10 mM FTE solution at temperature of 20°C (a) film thickness of FTE SAM, and (b) water contact angle.

Contact angle measurements were obtained using a goniometer, measuring the advancing angle from 2 to 20 microliter drop sizes, of purified water upon polymer films at room temperature. Films were cast on metal plates and allowed to dry slowly from chloroform solutions. Several spots were measured on each film and the results averaged. 

The low temperature ene reactions of 4-substituted-l,2,4-triazoline-3,5-diones (RTD) were used to modify polydiene surfaces. Hydrophilic surfaces (contact angles with water of 30-50°) were obtained on polybutadiene, poly-isoprene and styrene-butadiene copolymers by first treating the polymer at room temperature with RTD (R=Ph,... 

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