Search results for "Sessile drop technique"
showing 6 items of 6 documents
Measuring the Contact Angle of Individual Colloidal Particles.
1998
The aim of this study was to measure the contact angles of individual colloidal spheres ( solidus in circle 4.4 µm) and compare it to contact angles obtained on similarly prepared planar surfaces. For this purpose the particles were attached to atomic force microscope cantilevers. Then the force between the particle in aqueous medium and an air bubble was measured versus the distance. From the resulting force curves we obtained contact angles and detachment forces of single particles. Contact angles of gold coated silica particles were adjusted between 20 degrees and 100 degrees by self-assembling monolayers from different mixtures of undecanethiols and omega-hydroxy undecanethiols from sol…
On the topographic and energetic surface modifications induced by laser treatment of metallic substrates before plasma spraying
2003
Abstract Laser surface cleaning has been proven as a very suitable technique for the substitution of some surface preparation steps, such as wet cleaning and grit blasting. The mechanisms involved in short pulsed laser ablation include the absorption of the laser light and conversion into heat via collisional processes. Ejection of matter is achieved either by direct vaporization or hydrodynamical sputtering. This article aims at clarifying the laser–matter interaction mechanisms and effects on metallic materials for different surfaces initial roughness and laser beam energy densities. Both topographic and energetic modifications are investigated by SEM observations, roughness characterizat…
Microsphere tensiometry to measure advancing and receding contact angles on individual particles
1999
In this paper, a method to measure the advancing and receding contact angles on individual colloidal spheres is described. For this purpose, the microspheres were attached to atomic force microscope cantilevers. Then the distance to which the microsphere jumps into its equilibrium position at the air-liquid interface of a drop or an air bubble was measured. From these distances the contact angles were calculated. To test the method, experiments were done with silanized silica spheres (4.1 μm in diameter). From the experiments with drops, an advancing contact angle of 101 ± 4° was determined. A receding contact angle of 101 ± 2° was calculated from the jump-in distance into a bubble. Both ex…
Reduction of the Interfacial Tension between Poly(dimethylsiloxane) and Poly(ethylene oxide) by Block Copolymers: Effects of Molecular Architecture …
1997
Interfacial tensions σ were measured by means of the sessile drop method for mixtures of poly(ethylene oxide) [PEO, Mw = 41 kg/mol] with five samples of poly(dimethylsiloxane)s [PDMS, Mw ranging fr...
Effects of Gamma Irradiation on the Kinetics of the Adsorption and Desorption of Hydrogen in Carbon Microfibres
2013
In this study, three types of carbon fibres were used, they were ex-polyacrylonitrile carbon fibres with high bulk modulus, ex-polyacrylonitrile fibres with high strength, and vapour grown carbon fibres. All the samples were subjected to a hydrogen adsorption process at room temperature in an over-pressured atmosphere of 25 bars. The adsorption process was monitored through electrical resistivity measurements. As conditioning of the fibres, a chemical activation by acid etching followed by ¿-ray irradiation with 60Co radioisotopes was performed. The surface energy was deter-mined by means of the sessile drop test. Both conditioning treatments are supplementary; the chemical activation works…
Control of endothelial cell adhesion to polymer surface by ion implantation
2001
The bio-compatibility of ion implanted polymers has been studied by means of in vitro attachment measurements of bovine aorta endothelial cells. The specimens used were polystyrene (PS), polyethylene (PE), polypropylene (PP) and expanded polytetrafluoroethylene (ePTFE). He+ and Ne+ ion implantation were performed at an energy of 150 keV with fluences between 1 × 1013 to 1 × 1017ions/cm2 at room temperature. Wettability was estimated by means of a sessile drop method. The chemical and physical structures of ion implanted polymers were investigated by contact angle measurements, atomic force microscopy and X-ray photoelectron spectroscopic analysis in relation to cell attachment behavior. The…