Du Nouy Ring Method Research Articles

Photocrosslinkable tissue adhesive based on dextran

A biodegradable tissue adhesive was prepared from dextran urethane (Dex-U), which could be photocrosslinked under the UV irradiation, and steadily adhere to surface of gelatin and mouse skin, which simulate the human tissue. The structures of above Dex-U were characterized by FTIR, 1H NMR spectroscopy and XRD. The adhesion properties of result products was evaluated by lap-shear test and burst pressure test. The highest adhesion strength and burst pressure could reach to 2.99MPa and 35mmHg, respectively. The photopolymerization process of Dex-U was monitored by real time infrared spectroscopy (RTIR), and the surface tension of Dex-U solution was tested by du Nouy Ring method. The cytotoxicity of Dex-U also was evaluated. The relationship between all above properties and degree of substitution of Dex-U was assessed. The adhesive strength of Dex-U is significantly higher than that of fibrin glue. The obtained products present the potential to serve as tissue adhesive in medical area in the future.

Interfacial Behavior of Cyanex 272 and Mass Transfer Kinetics of Ytterbium Using the Constant Interfacial Area Cell

The interfacial behavior of Cyanex 272 has been investigated using the Du Nouy ring method. Different adsorption isotherms such as the Gibbs and Szyszkowski isotherms have been found as fitting well to the experimental data. The values of interfacial excess at the saturated interface increase in the following order: n-heptane > cyclohexane > CCl4 > toluene > benzene > chloroform, explained according to the stronger solution effect of aromatic hydrocarbon. The effects of temperature, acidity, and ionic strength of the aqueous phase on the interfacial activity of Cyanex 272 are also examined and explained in detail. Moreover, the reaction orders against Cyanex 272 predicted from the interfacial tension isotherms are in agreement with the order determined experimentally, which suggests that the interfacial activity of Cyanex 272 can provide enough strong evidence quantitatively supporting the interfacial mechanism.

Effects of Spacers on Surface Activities and Aggregation Properties of Anionic Gemini Surfactants

AbstractThis present article employs four anionic Gemini surfactants with different spacer groups and investigates their physicochemical and aggregation properties. The critical micelle concentration (CMC), surface tension at CMC (γCMC) and C20 of these surfactants have been investigated using the du Nouy ring method. The aggregation number (N) was determined with intrinsic fluorescence quenching method using pyrene as a fluorescence probe and benzophenone as a quencher. Results show that these anionic Gemini surfactants have lower CMC and C20 values compared with those conventional ones and show higher surface activity. As expected, the spacer plays an important role in the aggregation properties of Gemini surfactants. Under experimental conditions, Gemini B–D with an alkoxylated group as spacer has a lower CMC and a higher aggregation number than Gemini A with methylene as spacer. For Gemini B–D, the CMC and aggregation number values decrease with the increasing flexible spacer length. The micropolarity also affects the aggregation of the present anionic Gemini surfactants. The micropolarity of micelle becomes low when the concentration of surfactants increases. Aggregation numbers of surfactants increase and fluorescence intensities decrease with the increasing concentration of NaCl. These results will help us to understand the relationship between the architectures of Gemini surfactants and their various properties in aqueous solution.

Research of oxygen mass transfer through the air–water surface at low bulk concentrations of surfactants

Oxygen transfer from the gaseous to the liquid phase is often technologically a very energy-consuming process. We studied the influence of small alcohol molecules (1-butanol, 2-butanol, 2-methyl-propanol, and 2-methyl-2-propanol) as surfactants to oxygen permeability and addressed the importance of experimental methodology. The oxygen mass transfer rate in the air–water surface layer was calculated by using an original technique and the results were compared to the surface tension values obtained by the Du Nouy ring method. Our experiments revealed that oxygen permeability was inhibited already at very low surfactant concentrations (0.1–1 mmol/L), whereas a considerable increase in the surface tension was observed in a 1000-fold higher concentration range. These results demonstrate the importance of methodological considerations in the research of surface action of surfactants.

Interfacial behavior of primary amine N1923 and the kinetics of thorium(IV) extraction in sulfate media

The influences of additive, diluents, temperature, acidity of the aqueous phase on the interfacial behavior of primary amine N1923 in sulfate media have been investigated using the Du Nouy ring method. In addition, the effect of concentration of thorium(IV) loaded in the organic phase on the interfacial tension has also been studied. The interfacial tension isotherms are processed by matching different adsorption equations such as the Gibbs and the Szyszkowski. The surface excess at the saturated interface ( Γ max) and the minimum bulk concentration of the extractant necessary to saturate the interface ( C min) under different conditions are calculated according to two adsorption equations to be presented in comprehensive tables and figures. It appears that primary amine N1923 has strong interfacial activity and behaves very differently in various diluents systems. The surface excess at saturated interface increase with the type of diluents in the following order: chloroform < aromatic hydrocarbons < aliphatic hydrocarbons. The relationship between the interfacial activity and kinetics of thorium extraction by primary amine N1923 has been discussed by considering different factors. However, the interfacial activity of primary amine N1923 is only a qualitative parameter suggesting the interfacial mechanism for thorium extraction, it cannot give strong evidence quantitatively supporting this mechanism.

Surface Tension of Liquid Fluorocompounds

This work aims at studying the surface tension of some linear, cyclic, aromatic, and α-substituted perfluorocarbons. Despite its fundamental interest, information about this property for these compounds is scarce, and the available data are old and present strong discrepancies among each other. The measurements were carried out in the temperature range (283 to 327) K with the Du Nouy ring method. The analysis of the experimental data shows that the molecular structure is an important factor in the surface behavior of the studied compounds since the aromatic fluorocompounds present the highest surface tensions, followed by the cyclic and substituted fluorocompounds. The linear n-perfluoroalkanes exhibit the lowest surface tension values, slightly increasing with the carbon number. The surface thermodynamic functions such as surface entropy and enthalpy were derived from surface tension values and are also reported. The experimental data were compared against the Faizullin correlation, and it is shown that ...

Interfacial behavior of DEHEHP and the kinetics of cerium(IV) extraction in nitrate media

The effects of diluents, temperature, acidity, and ionic strength of the aqueous phase on the interfacial properties of DEHEHP have been extensively investigated using the Du Nouy ring method. In addition, the effect of cerium(IV) concentration loaded in the organic phase on the interfacial tension has also been studied. With the increase of DEHEHP concentration, the value of interfacial tension ( γ) decreases in the studied system, which shows that DEHEHP has interfacial activity as a kind of surfactant. The surface excess at the saturated interface ( Γ max ) and the minimum bulk concentration of the extractant necessary to saturate the interface ( C min ) under the different conditions are calculated according to two adsorption equations such as the Gibbs and Szyszkowski functions to be presented in comprehensive tables and figures. The relationship between the interfacial activity of DEHEHP and cerium(IV) extraction kinetics by DEHEHP has been discussed by considering different factors such as the effects of diluents and temperature. However, the interfacial activity parameter of extractant only is a qualitative parameter, but cannot provide strong enough evidence to quantitatively explain the relationship between extraction kinetics and interfacial properties of an extractant.

Interfacial Activity of sec‐Nonylphenoxy Acetic Acid and Kinetics of Yttrium Extraction

The interfacial behavior of sec‐nonylphenoxy acetic acid (CA‐100) at various diluents/(H, Na)Cl interfaces was examined using the Du Nouy ring method. Different adsorption isotherms such as the Gibbs and Szyszkowski were in good agreement with the experimental data. The values of interfacial excess at saturated interface increase in the following order: n‐heptane > kerosene > cyclohexane > CCl4 > toluene > benzene > chloroform. The effects of temperature, acidity, and ionic strength of the aqueous phase on the interfacial activity of CA‐100 were also examined. The interfacial‐activity data were used to discuss the mechanism and kinetics of yttrium (Y) extraction.

Wettability of Chitosan Coating Solution on‘Fuji’ Apple Skin

ABSTRACT:Wettability of chitosan coating solutions on‘Fuji’ apple skin in different surfactant concentration (Tween 80: 0, 10, 100, 1000 ppm) was investigated using the Du Nouy ring method and the sessile‐drop method. The surface property of‘Fuji’ apple skin as a coated solid surface was characterized by the Zisman plot. The critical surface tension of‘Fuji’ apple skin was 18.7 dyne/cm. The surface tension of the chitosan coating solution was too high (61.5 dyne/cm) to wet the apple skin. Tween 80 as surfactant in water‐borne coatings reduced the surface tension of the coating solution and enhanced its wettability. Surface morphology of the coated film was observed by scanning electron microscope. Surfactant driven autophilicity improved the adhesive force between coating solution and associative apple skin, and decreased the contact angle of coating solution.

Effect of plasticizer on the dynamic surface tension and the free volume of Eudragit systems.

The purpose of the present study was to determine the changes of dynamic surface tension of aqueous Eudragit dispersions quantitatively and compare these data with the free volume of the free films formed from several dispersions of different dibutyl sebacate (DBS) concentrations. Eudragit L 30D and Eudragit RL 30D aqueous colloidal polymer dispersions and their cast free films were examined. The concentration of DBS varied in the dispersions from 0 to 20%. The dynamic surface tension of the dispersions were measured by the Du Nouy ring method while the free volume of cast films were determined by positron annihilation spectroscopy. The obtained results show that dynamic surface tension measurements indicate the white point (WP) of Eudragit dispersions by a significant standard deviation increase. This may suggest the applicability of dynamic surface tension measurements for the determination of the WP of polymeric dispersions. A decrease in the WP temperature of Eudragit dispersions with an increasing plasticizer concentration was observed up to the DBS concentration of 10% w/w. Above this concentration neither the WP of the polymer dispersion nor the free volume of the free films of the polymer were changed remarkably.

A Study of the Dynamic Spreading of Inks onto Various Ink-jet Substrates

The aim of this paper is to present some results concerning ink/substrate interactions in the context of ink-jet printing. During the impact of an ink drop onto the substrate, the interface properties of the materials play a crucial role, which may determine, to a certain extent, the spreading of the ink droplets, and therefore the ensuing print quality.In this study, several substrates, including papers of various quality levels and a polymer film, were analysed. Classical methods of porosity determination were applied, together with roughness measurements. The surface energy of these substrates was calculated from measurements of contact angles with various liquids.A series of commercial ink-jet inks, and the corresponding model solvents were analysed. Their surface tension was measured by the DuNouy ring method and then,.their spreading kinetics onto the different substrates were examined using a high-speed camera coupled with an image analysis system.Various situations were observed. These results were correlated to quality tests conducted with commercial ink-jet printers using the same inks/ substrates systems.

The Effect of Temperature and Polymer Concentration on Dynamic Surface Tension and Wetting Ability of Hydroxypropylmethylcellulose Solutions

The purpose of the present study was to evaluate quantitatively the changes of dynamic surface tension and contact angle of hydroxypropylmethylcellulose (HPMC) aqueous solutions as a function of temperature and polymer concentration of the examined solutions. HPMC aqueous solutions of different concentrations (1%, 2%, 3%, 4% w/w) were prepared without plasticizer and with 1% w/w Lutrol F127. Dynamic surface tension of the prepared solutions was determined by the Du Nouy ring method of the KSV Sigma 70 computer-controlled and programmable tensiometer. The dynamic contact angle of Avicel PH-101 tablets was measured against HPMC solutions of various concentrations by the plate method of the KSV Sigma 70 tensiometer. The obtained results indicate that dynamic surface tension measurement can be applied for the accurate determination of the thermal gelation temperature of the prepared HPMC solutions. With increasing concentration of HPMC, dynamic contact angle values of solutions also increased, thus decreasing the spreading behavior on the surface of Avicel tablets.

Colloidal Protein Solutions as a New Standard Sensor for Adhesive Wettability Measurements

Wetting experiments are carried out for the investigation of the interfacial interactions that take place when various solid materials are in contact with protein colloidal solutions. These materials are chosen because they are widely used in the field of orthopedic surgery. Contact angles (sessile drop) and surface tension (du Nouy's ring method) are measured in standardized conditions which take into account the various parameters disturbing wetting phenomena. An original cumulative deposits method (CDM) described here permits observation of the evolution of the wettability and allows estimation of the protein adhesion rate. Two families of materials emerge according to their behavior when they are in contact with the protein solution. One set (a chromium cobalt alloy and two polyethylenes) presents no detectable adhesion. The other set (stainless steel, zirconia, alumina, virgin and nitrogen implanted titanium alloy) shows a cumulative adhesion of proteins. We propose to adopt a BSA buffered solution as a referential sensor to characterize solid surfaces. From the CDM, the practical parameterP*, called the adhesive wettability power, can be used in order to analyze and classify biomaterials.

Application of a modified drop-collapse technique for surfactant quantitation and screening of biosurfactant-producing microorganisms

A drop-collapse method has been refined for use as both a qualitative assay to screen for surfactant-producing microbes, and as a quantitative assay to determine surfactant concentration. The assay is rapid, easy to perform, reproducible and requires little specialized equipment. The assay is performed in a 96-microwell plate, where each well is thinly coated with oil. A 5 μL sample droplet is added to the center of a well and observed after 1 min. The droplet will either bead up, spread out slightly or collapse, depending on the amount of surfactant in the sample. The basis for this method is the type of oil used to coat each well. In the qualitative method, each well is coated with 1.8 μL of Pennzoil® and either the drop collapses, indicating the presence of surfactant (a positive result), or the drop remains beaded, indicating the absence of surfactant (a negative response). In the quantitative method, each well is coated with 2 μL of mineral oil, and a dissecting microscope is used to measure the diameter of the droplet at 1 min. Results with both a test biosurfactant (rhamnolipid) and a test synthetic surfactant (sodium dodecyl sulfate) indicate a direct linear correlation between droplet diameter and surfactant concentration. The drop-collapse method has several advantages over commonly used methods that measure surface tension, such as the du Nouy ring method; a smaller volume is required (5 μL vs. 20 mL), the effective range of measurement is greater and it does not require specialized equipment.

Preformulation Studies on Freund's Incomplete Adjuvant Emulsion

Freund's Incomplete Adjuvant (FIA), which is used in vaccine therapy, is a water-in-oil emulsion delivery system consisting of an aqueous internal phase containing an antigenic protein dispersed in an external phase containing a mixture of mannide monooleate and light mineral oil. Preformulation studies are reported in this investigation for FIA emulsion. The preformulation studies included the determination of the critical micelle concentration (CMC) of the formulations investigated, the surface activity of mannide monooleate at the interface between the oil phase and the aqueous phase containing ovalbumin as the model antigenic protein, and the effect of ovalbumin on the surface activity at the interface. The influence of the concentration of mannide monooleate and/or ovalbumin on the interfacial tension between light mineral oil and either purified water or 0.9% w/v normal saline solution was measured by the DuNouy Ring Method at 25°C. The CMC was determined experimentally from the relationship between the concentration of the surface active agent in each formulation and the interfacial tension. The number of moles of the surface active agent per unit area at the interface (surface excess concentration) was calculated from the Gibbs' Adsorption equation. The results indicated that mannide monooleate was an effective surface active agent since the formulation containing only mannide monooleate provided the lowest magnitude of CMC. The presence of the surface active agent, mannide monooleate and/or ovalbumin, in the formulations studied reduced the interfacial tension between the two phases. The surface activity was influenced by the presence of an electrolyte (sodium chloride), a protein (ovalbumin), or mannide monooleate in the formulation. The presence of antigenic proteins in the aqueous phase of a water-in-oil emulsion influenced the effectiveness of a surface active agent in the formulation.

Surface and interfacial tensions of aqueous dispersions of charged colloidal (clay) particles

We have measured (du Nouy ring and maximum bubble pressure methods) suspension–air surface tensions of aqueous suspensions of montmorillonite and have observed that these surface tensions are larger than those of pure water at the same temperatures. Further measurements have shown that dispersed montmorillonite also increases the suspension–toluene interfacial tension compared with that of pure water–toluene. Similar measurements on aqueous suspensions of kaolinite have yielded suspension–air interfacial tensions with uncertainties as large as the observed (small) effect, and also shown that the suspension–toluene interfacial tension is decreased (opposite to the effect of montmorillonite) by amounts larger than the experimental uncertainties. Measurements of maximum bubble pressures at different flow rates have provided information about the effect of surface age on observed surface tensions.

Surface tension of aqueous lithium bromide + 2-ethyl-1-hexanol

The surface tension of an aqueous lithium bromide solution containing an active surfactant (2-ethyl-1-hexanol) was measured over the lithium bromide concentration range 40 [<=] C[sub LiBr] [<=] 60 wt % and surfactant concentration range 0 [<=] C[sub sur] [<=] 200 ppm. The Du Nouy ring method was employed to determine the surface tension.

Lower critical solution coexistence curve and physical properties (density, viscosity, surface tension, and interfacial tension) of 2,6-lutidine + water

The coexistence curve and physical property data (densities, viscosities, surface tensions, and interfacial tensions of the equilibrated coexisting phases) for 2,6-lutidine+water have been determined over the range 34-60 o C, and the density and viscosity differences calculated. The compositions were determined through the refractive index at 22 o C, densities by a commercial electronic oscillating U-tube, viscosities by a U-tube viscometer, surface tensions by a du Nouy ring method, and interfacial tensions by a spinning drop interfacial tensiometer

Interfacial tension in systems with a supercritical component at high pressures

AbstractInterfacial tension of the binary systems pelargonic acid/ethane, pelargonic acid/carbon dioxide, linoleic acid/ethane, and linoleic acid/carbon dioxide was measured at 313, 333, and 353 K and pressures ranging up to 250 bar, using the capillary rise and Du Nouy ring methods. Both these methods yield similar values. The surface excess of supercritical components is deduced from the measurement results with the aid of Gibbs adsorption equation. The surface excess concentration increases with increasing gas activity, runs through a pronounced maximum, later decreasing rapidly to very small values. Near the surface excess maximum, a falling film of fatty acids disintegrates into a mist of tiny droplets.

Comparison of dynamic and static interfacial tension at aqueous/perfluorocarbon interfaces

The dynamic and static interfacial tension of four different perfluorocarbons at aqueous interfaces were compared using a PTFE Wilhelmy plate method and a platinum du Nouy ring method, respectively. The dynamic values were measured continuously for at least 6 h without disturbing the interfaces, and the static values were measured after 20 min of aging. The perfluorocarbons investigated were 1,2- trans-(bisperfluorobutyl) ethylene (F44E), perfluorodecalin, perfluoroheptane, and I- H-perfluoroheptane. “Surface slip” due to the high affinity of platinum for the aqueous phase caused premature breakage of the interface during the du Nouy ring measurements, and consequently the static values were lower than the dynamic values. The PTFE Wilhelmy plate method proved an excellent technique for studying systems in which the interfacial tension changed as a function of the age of the interface, such as the perfluorocarbon/PTFE/double-distilled and deionized water interface. The dynamic interfacial tension of perfluoroheptane and 1- H-perfluoroheptane increased slightly with time, whereas that of F44E and perfluorodecalin decreased with time. The dynamic interfacial tension profiles appeared to be a function of both the molecular weights and structures of the perfluorocarbons.