• Korean Journal of Materials Research
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• v.19 no.2
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• pp.111-114
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• 2009

For the fabrication of core-shell structure bimetallic lead-free solder balls, both the critical temperature ($T_{cr}$) for the phase separation of two immiscible liquid phases and the temperature coefficient of the interfacial tension between the two separated liquid phases are required. In order to obtain this information, the temperature dependence of the surface tension of 60%Bi-24%Cu-16%Sn(-REM) alloys was measured using the constrained drop method. The slope of the temperature dependence of the surface tension changed clearly at a critical temperature for the separation of two immiscible liquid phases. The critical temperature of the 60%Bi-24%Cu-16%Sn alloy was estimated to be 1097K. An addition of 0.05% Ce decreased the critical temperature to 1085K, whereas that of 0.05% La increased it to 1117K. It was found that the surface tension and its temperature coefficient of the 60%Bi-24%Cu-16%Sn alloy were slightly increased by the addition of 0.05% Ce and 0.05% La. In addition, additions of Ce and La increased the temperature coefficient of the interfacial tension.

• Journal of the Korean Chemical Society
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• v.9 no.3
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• pp.124-127
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• 1965

The surface tension of the solution of dodecylpridinium bromide was measured by the ring method over the range $25^{\circ}\; to\; 45^{\circ}C.$ The critical micelle concentration was determined from the change of the surface tension of solution with concentration. The temperature dependence of the critical micelle concentration was also investigated. The result was compared with Adderson and Taylor's data determined by the conductivity method.

• Macromolecular Research
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• v.17 no.6
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• pp.388-396
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• 2009

The surface properties (water sorption and repellency, adhesion) are closely related to the surface tension of polymer solids. The critical surface tension (${\gamma}_c$) and surface tension (${\gamma}_s$) of a polymer solid were estimated by the contact angle method by our quantitative imaging system. BPDA (3,3',4,4'-biphenyl tetracarboxylic dianhydride)-BAPP (1,3-Bis(4-aminophenoxy) propane) polyimide was successfully synthesized. The ${\gamma}_c$ values were analyzed by a Zisman plot, a Young-$Dupr\acute{e}$-Good-Girifalco plot, and a log ($1+cos{\theta}$) vs log ${\gamma}_L$ plot. The ${\gamma}_s$ value of BPDA-BAPE polyimide was evaluated using the geometric mean equation and our multiple regression analysis. The calculated values of ${{\gamma}_s^d$ (a dispersion component), ${{\gamma}_s^p$ (a polar component), ${{\gamma}_s^h$ (a hydrogen bonding component), and ${\gamma}_s$ were 30.79, 9.32, 0.20, and 40.31 $mN{\cdot}m^{-1}$, respectively. The ${\gamma}_s$ of BPDA-BAPP polyimide containing both a methylene group and an ether group was larger than that of the polyimide containing only a methylene group.

• Journal of the Korean Applied Science and Technology
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• v.23 no.3
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• pp.185-191
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• 2006

It is desirable to have an accurate expression on the temperature dependence of surface(or interfacial) tension ${\sigma}$, because most of the interfacial thermodynamic functions can be derived from it. There have been proposed several equations on the temperature dependence of the surface tension, ${\sigma}(T)$. Among them $E{\ddot{o}}tv{\ddot{o}}s$ equation and the one modified by Katayama, which is called Katayama equation, for improving accuracies of $E{\ddot{o}}tv{\ddot{o}}s$ equation close to critical points, have been most well-known. In this article Katayama equation is interpreted on the basis of the cell model to understand the nature of the equation. The cell model results in an expression very similar to Katayama equation. This implies that, although $E{\ddot{o}}tv{\ddot{o}}s$ and Katayama equations were obtained on the basis of experimental results, they have a sound theoretical background. The Katayama equation is also modified with the phase volume replaced with a critical scaling expression. The modified Katayama equation becomes a power-law equation with the exponent slightly different from the value obtained by critical-scaling theory. This implies that Katayama equation can be replaced by a critical-scaling equation which is proven to be accurate.

• Proceedings of the KIEE Conference
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• 1987.11a
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• pp.508-510
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• 1987

The variation electrical resistivity of Carbon black filled polymers with volume percent of carbon black was investigated. The relationships between the surface tension of polymer and dispertion effect of carbon black were studied to find the steep drop of electrical resistivity. The critical volume percent of carbon black increased with the increasing surface tension of polymer. The PTC intensity decreased with the increasing volume percent of carbon black.

• 한국전산유체공학회:학술대회논문집
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• 2003.10a
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• pp.162-163
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• 2003

• Journal of the Korea Institute of Military Science and Technology
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• v.4 no.1
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• pp.207-215
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• 2001

Plastic bonded explosive(PBX) is mainly composed of the nitramine-ploymer compositions. PBX is characterized by high velocity and pressure of detonation, low vulnerability and good thermal stability. Many important applications of PBX require the good adhesion between nitramine crystals and the binder. For PBXs as well as propellants, where good mechanical properties are of great importance, dewetting therefore must be prevented by strong adhesion between filler-binder. Adhesion depends on surface characteristics of filler and binder. In order to design for better adhesion, an understanding of the surface properties of explosive and binder is required. The surface free energies are calculated from contact angle values by the method of Kaelble. Critical surface tension of solids are calculated by Zisman plot. Critical surface tension is a useful parameter for characterizing the wettability of solid surface. In this study, HMX and 3 kinds of copolymers are selected, since they are widely used in many plastic bonded explosives. The technical objective of this investigation is to predict the interaction between filler and binder from their surface free energies.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.1
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• pp.23-30
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• 2014

Purpose: The present study was aimed to figure out the correlation amongst the evaluation methods for critical micelle concentration, surface tension and protein cleaning efficacy to evaluate cleaning efficacy of contact lens care products. Methods: The critical micelle concentration of surfactants and the actual concentration of surfactants in contact lens care solutions were investigated by employing references published and related information. Surface tension of contact lens care solutions was measured by surface tension device at $25{\pm}1^{\circ}C$, and contact lenses made of lotrafilcon A, comfilcon A and balafilcon A were washed with contact lens care solutions after the incubation in artificial tears for 14 days and their cleaning efficacy was compared. Results: Among the 22 contact lens care products, 9 products provided the label of the concentration of surfactant, and 7 products showed higher concentration of surfactant than the critical micelle concentration reported in references. As a result of measuring surface tension, the surface tension of lens care products for soft contact lens was generally lower than other care products. When examined the removal effect of protein deposited on lens surface, it was known that the care products having lower surface tension showed higher protein removal efficiency. Conclusions: The surface tension is low when surfactant concentration in contact lens care solutions is high, and the removal effect of protein deposited is accordingly increased with the decrease of surface tension. Thus, these indicate the correlation amongst the evaluation methods for cleaning efficacy.

• Journal of Korean Society on Water Environment
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• v.29 no.5
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• pp.674-680
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• 2013

Basic studies for the treatment of particulate organic substances contained in wastewater by flotation have been conducted. Four kinds of plastics were chosen as the possibly existing organic particles in wastewater and the Zisman plots for these substances were constructed by measuring the contact angle of liquids on their surfaces. The critical surface tensions for these organic substances were estimated based on the constructed Zisman plot and the floatability of organic substances were regarded to be related with their molecular structure. The existence of dissolved organic substances such as a surfactant was observed to affect the extent of flotation of particulate organics. In addition, the consideration of work of adhesion was thought to be better than adopting the critical surface tension as the analytical basis in the operational design of flotation process of organic particles.

• Archives of Pharmacal Research
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• v.7 no.2
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• pp.109-113
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• 1984

The critical micelle concentration (CMC) of crude ginseng saponin in water was determined by fluorometry and surface-tension measurement. These two methods gave the the CMC value, 0.015g/100ml AND 0.013G/100ml, respectively. The surface excess of the saponin and the area occupied by a saponin molecule at the monolayer adsorbed at air and waterinterface were calculated employing Gibbs adsorption equation. The presence of salt increased the surface activity of the saponin: it decreased the CMC, the surface tension at the CMC and the area occupied by a saponin molecule at the monolayer, which should be due to the salting-out effect of the salt.