Assessment Of Wettability Research Articles

Physico-chemical biomarkers based on a non-contact wettability assessment system

Physico-chemical biomarkers based on a non-contact wettability assessment system

Contact angle measurement on rough surfaces: the missing link

Wettability of rough surfaces is critical for many processes and materials. The most prevalent technique for characterizing wettability is the measurement of contact angles. Unfortunately, the routine assessment of wettability by contact angle measurement is not as simple as it appears to be. The main reason is that most real surfaces are characterized by a range of seemingly stable contact angles, and not by a single value. Moreover, the technique of contact angle measurement has not been updated to utilize current theoretical understanding with regard to the most stable state of the drop and its symmetry. Here we experimentally demonstrate the validity of the theoretical observation that a sufficiently large drop must be axisymmetric at the most stable thermodynamic state of the system. This is the link missing in current methodology between the measurement of the apparent contact angle and its interpretation in terms of the ideal (Young) contact angle.

Functional biocompatibility testing of silicone breast implants and a novel classification system based on surface roughness

Increasing numbers of women undergo breast implantation for cosmetic and reconstructive purposes. Contracture of the fibrous capsule, which encases the implant leads to significant pain and reoperation. Texture, wettability and the cellular reaction to implant surfaces are poorly understood determinants of implant biocompatibility. The aim of this study was to evaluate the in-vitro characteristics of a range of commercial available implants using a macrophage based assay of implant biocompatibility and a quantitative assessment of wettability and texture. Thirteen commercially available surfaces were subjected to wettability and texture characterisation using scanning and laser confocal microscopy. THP-1 macrophages were cultured on their surfaces and assessed using Integrin αV immunocytochemistry, SEM and RT-PCR for the expression of TNF-Alpha, IL-6, IL-10 and a cytokine array for the production of TNF-alpha, IL-10, IL-1RA and IL1β; important indicators of inflammation and macrophage polarization. Textured surfaces can be accurately sub-categorized dependent upon roughness and re-entrant features into four main types (macro, micro, meso and nano-textured surfaces). Significant (P < 0.0001) differences in implant hydrophobicity and texture exist. Certain surfaces promoted poor macrophage polarization and an innate potential to foster a proinflammatory response. A subgroup analysis showed that texture had a variable effect on markers of inflammation in these surfaces. We propose a classification of implant surfaces based on roughness and present a macrophage based assay of breast implant biocompatibility with a quantitative assessment of implant wettability and texture. The breast implant surface-cell interaction is variable and sufficient to alter healing response and capsular contracture fate in-vivo.

Wettability assessment of plasma-treated PBO fibers based on thermogravimetric analysis

Changes in the surface wettability of poly(p-phenylene benzobisoxazole) (PBO) fibers were investigated by thermogravimetric analysis (TGA) following an air dielectric barrier discharge (DBD) plasma treatment. The results were then supplemented and confirmed by scanning electron microscopy (SEM), dynamic contact angle analysis (DCAA), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) measurements. After exposure to the DBD plasma at a pre-determined power level, TGA analysis showed that the residual rates retained by the PBO composites decreased, which meant an increase in the amount of resin coating the PBO fibers in the composites. Observations by SEM confirmed that there was more resin adhering to the treated PBO fibers and the wetting behavior of resin on the fibers was greatly improved. Meanwhile, DCAA for the treated fibers showed a significant enhancement in fiber surface free energy. XPS and AFM were performed in order to reveal any variations in fiber surface activity and surface morphology resulting from the surface treatment. The resulting data showed that increases in oxygen-containing polar groups and surface roughness on the plasma-treated PBO fibers contributed to the above improved wetting behavior. With comprehensive analyses, it was concluded that TGA could be used as a supporting method assessing the surface wettability of PBO fibers before and after air DBD plasma treatment.

Non-contact wettability assessment system for tissue engineering

Non-contact wettability assessment system for tissue engineering

Performance characteristics of protective coatings under low-temperature offshore conditions. Part 1: Experimental set-up and corrosion protection performance

Six organic coating systems are investigated according to their performance under Arctic offshore conditions. Four performance groups are considered: corrosion protection performance, performance under mechanical loads, surface status and icing performance. The investigations involve the following tests: accelerated corrosion protection/ageing tests, tests for coating adhesion, hoarfrost accretion measurements, impact resistance tests, abrasion tests, and wettability tests. The test conditions are adapted to Arctic offshore conditions, which mainly cover low temperatures down to −60°C. A testing facility for hoarfrost performance tests is developed. The coating systems are organic coating systems which differ in generic coating material, hardener, number of layers, dry film thickness and application method. Part 1 describes the testing programme and discusses the results of the corrosion protection performance tests. Part 2 discusses the results of the surface topography measurements, wettability assessment, hoarfrost formation and mechanical testing. A procedure for the ranking of the coating performance is developed. The best performing system in the scope of evaluation is a three-layer system with high thickness (1400μm), consisting of two glass-flake reinforced epoxy coats and a polyurethane topcoat.

Performance characteristics of protective coatings under low-temperature offshore conditions. Part 2: Surface status, hoarfrost accretion and mechanical properties

Six organic coating systems are investigated according to their performance under Arctic offshore conditions. Four performance groups are considered: corrosion protection performance, performance under mechanical loads, surface status, and icing performance. The investigations involve the following tests: accelerated corrosion protection/ageing tests, tests for coating adhesion, hoarfrost accretion measurements, impact resistance tests, abrasion tests, and wettability tests. The test conditions are adapted to Arctic offshore conditions, which mainly cover low temperatures down to −60°C. A testing facility for hoarfrost performance tests is developed. The coating systems are organic coating systems which differ in generic coating material, hardener, number of layers, dry film thickness and application method. Part 2 discusses the results of surface topography measurements, wettability assessment, hoarfrost formation and mechanical testing. A procedure for the ranking of the coating performance is developed. The best performing system in the scope of evaluation is a three-layer system with high thickness (1400µm), consisting of two glass-flake reinforced epoxy coats and a polyurethane topcoat.

Effect of particle size on the measurement of the apparent contact angle in sand of varying wettability under air-dried conditions

Changes in the wettability of soil are known to affect several processes such as infiltration and the shear strength of soil. In this study, the wettability of a medium to fine sand was chemically modified by using different concentrations of dimethyldichlorosilane (DMDCS). The sessile drop method (SDM) was used for the assessment of wettability of hydrophobised Leighton Buzzard Sand (LBS). The results demonstrate that beyond a concentration of 2 g per kg of LBS, the finer fraction had its apparent contact angle (ACA) increased up to 115° while the maximum ACA attained by the coarser fractions was 100°. At such high concentration of DMDCS, the effect of trapped air, which is known to increase the ACA, was found to be either small or insignificant. The standard deviations of the ACAs agreed well with past studies. The most important factors contributing to the water-repellent behaviour of chemically synthesised sand were attributed to the characteristics of the particles; these include surface area and particle shape.

非接触濡れ性評価システムの自動化

非接触濡れ性評価システムの自動化

Surface modification of polymeric materials by cold atmospheric plasma jet

• We investigate polymer surface modification by atmospheric pressure plasma jet APPJ. • Jet operation conditions for uniform surface modification were determined. • The APPJ added O atoms to the polymer surface and also enhanced the roughness. • The degree of polymer surface modification by APPJ and DBD were compared. • The APPJ is more efficient in attaching O atoms and produces less polymer fragments. In this work we report the surface modification of different engineering polymers, such as, polyethylene terephthalate (PET), polyethylene (PE) and polypropylene (PP) by an atmospheric pressure plasma jet (APPJ). It was operated with Ar gas using 10 kV, 37 kHz, sine wave as an excitation source. The aim of this study is to determine the optimal treatment conditions and also to compare the polymer surface modification induced by plasma jet with the one obtained by another atmospheric pressure plasma source – the dielectric barrier discharge (DBD). The samples were exposed to the plasma jet effluent using a scanning procedure, which allowed achieving a uniform surface modification. The wettability assessments of all polymers reveal that the treatment leads to reduction of more than 40° in the water contact angle (WCA). Changes in surface composition and chemical bonding were analyzed by x-ray photoelectron spectroscopy (XPS) and Fourier-Transformed Infrared spectroscopy (FTIR) that both detected incorporation of oxygen-related functional groups. Surface morphology of polymer samples was investigated by Atomic Force Microscopy (AFM) and an increase of polymer roughness after the APPJ treatment was found. The plasma-treated polymers exhibited hydrophobic recovery expressed in reduction of the O-content of the surface upon rinsing with water. This process was caused by the dissolution of low molecular weight oxidized materials (LMWOMs) formed on the surface as a result of the plasma exposure.

Wplyw wyladowan koronowych na wlasciwosci warstwy wierzchniej polilaktydu

The paper investigates the effect of corona discharge (CD) treatment on the properties of surface layer (SL) of polylactide (PLA) film. The modification of PLA was carried out in the air and helium atmosphere and the results were compared on the basis of the assessment of wettability, surface free energy (SFE) calculated using Owens–Wendt method as well as the degree of oxidation (O/C) of the modified SL, determined by photoelectron spectroscopy.

Wettability Assessment and Surface Compositional Analysis of Aged Calcite Treated with Dynamic Water

The following study investigates the effect of brine ionic composition and salinity (a mixture we call dynamic water) on calcite surface wettability alteration using atomic force microscopy (AFM) a...

Analyzing capillary‐rise method settings for contact‐angle determination of granular media§

AbstractWater repellency is a relevant topic in soil‐science research due to its effects on vegetation growth, occurrence of surface runoff, infiltration, and erosion. Different methods have been adapted for the assessment of soil wettability by measuring the contact angle (CA), like the capillary‐rise method (CRM), where the liquid penetration dynamics into a dry sample is analyzed. However, questions related to sample preparation and the use of a suitable reference liquid in order to improve the reproducibility in such heterogeneous materials are still open. Different methods use ethanol as a reference liquid to quantify the degree of water repellency, like the molarity of ethanol droplets (MED), whereas other methods (CRM) suggest in addition n‐hexane as reference. To date, no generally accepted protocol has been invented to apply the CRM to soil particles. By using model porous materials with defined and stable levels of water repellency (silt, sand, and glass beads), CA results were compared for different initial settings of the sample. The main objective was to prove the CRM as a reliable and reproducible method to characterize soil wettability and to specify general guidelines for its application for granular materials in terms of sample size, sample‐packing procedure, and reference liquid. Results showed that a sample weight of ≈ 2 g has a relatively lower CA variation between replications. The packing procedure showed erratic results in CA, proving to be a critical factor in reproducibility. A uniform criterion of samples packing is recommended regarding application of CRM in soils. Regarding the reference liquid, n‐hexane should be preferred instead of ethanol for dynamic CA determination, because ethanol increased the tendency of CRM to overestimate angles due to dynamic effects, especially in finer‐textured materials (i.e., silt).

Wettability of mineral and metallic powders: Applicability and limitations of sessile drop method and Washburn's technique

Characterization of powder wettability is a prerequisite to the understanding of many processes of industrial relevance such as agglomeration which spans from pharmaceutical and food applications to metallurgical ones. The choice of the wetting fluid is crucial: liquid must wet the powder in order for agglomeration to be successful. Different methods for wettability assessment of powders were reported in the literature, however the sessile drop method and capillary rise test remain among the most widely employed because they are easy to perform and inexpensive. In this paper, the application and limitations of sessile drop method and capillary rise test on mineral and metallic surface were discussed. This work provides a collection of wettability measurements using several powders and binders which are involved in the manufacturing process of welding wires. Moreover a new reference liquid for the calibration of capillary rise method was proposed.

Wettability determination of core samples through visual rock and fluid imaging during fluid injection

Reservoir rock wettability is a key factor in oil recovery, as it controls the location, flow, and distribution of reservoir fluids. However, proper assessment of wettability is not an easy task and provides a number of challenges. Wettability is in parts determined by the history of the oil reservoir through mechanisms such as aging and fouling. Hence direct measurements on freshly exposed rock surfaces (e.g. on core plugs) are critical and might not represent the true wettability within the sample. We present a new and fast method for wettability determination based on the optical observation of injected fluids, which allows for wettability determination independent from the surface wettability state of the sample. Fluid behavior within the boundaries of the capillary regime is driven by capillary forces and thus by wettability, which is exploited for our method. We show that a combined optical white-light and fluorescence imaging technique provides excellent contrast for reliable observations. Based on this imaging technique, we successfully distinguish core samples with different internal wettability, independent of their surface state.

Wettability Assessment of Submicrometer Alumina Powder Using a Modified Washburn Method

The possibility to accurately measure the liquid–solid contact angle on submicrometer powders by means of a modified capillary rise setup using cold isostatically pressed powder compacts is reported. The geometric factor needed for the determination of the contact angle from liquid penetration data was calculated from the pore properties of the powder compacts. During the capillary rise experiments, the pellets retained their structural integrity and concomitant porosity ensuring the reproducibility of the contact angle values obtained.

Assessing Aptitude of Plated Ni–W Film as Mold Materials for Borosilicate Glass

We propose the Ni–W plating film as a mold material for the hot embossing of borosilicate glass. The lifetime of a Ni–W plating mold is important from a practical perspective. However, there have been no previous reports on the life of a mold. Contact angle has been reported as a parameter for the comparative assessment of wettability. In this report, we identified the components of borosilicate glass reacted with a Ni–W film by elemental analysis together with a wettability test. In the wettability test, increasing temperature caused a decrease in of contact angle, which is caused by the chemical reaction at the center of glass. In the results of the elemental analysis of the Ni–W film in contact with glass, Zn, a constituent of the glass, was not detected in the noncontact zone, but was detected in the contact zone. There is no binary alloy phase diagram of W–Zn. It is considered that W does not form an alloy with Zn. Results from the reaction of Zn on Ni indicated an increase in the wettability of borosilicate glass for the Ni–W plating film.

Siloxane-containing polymer matrices as coating materials

Coating materials based on siloxane-containing polymer matrices that had been modified with fluoropolymer or acrylic resins and applied as organic components of hybrid systems were examined. The optimal recipes of the dispersion systems, applied as polymer matrix precursors, were determined on the basis of factorial experiments, designed as 22 with additional ‘star’ experimental points to obtain greater accuracy in the resulting regression equations. The siloxane cage formation was based on the following crosslinking reactions of functional polysiloxanes: (1) hydrosilylation of vinyl groups; (2) condensation of silanol groups. Moreover, the molecular modeling, using P3 semi-empirical methods, was applied to build the model structure of a siloxane-containing polymer matrix. The surface properties of these coatings were studied using wettability assessments (dynamic contact angle and surface-free energy evaluation), atomic force microscopy (AFM), and X-ray electron microscopy (ESCA-XPS). The morphology, roughness, and structural regularity are discussed to illustrate the effects of the organic component on the surface properties. The most significant changes were observed in the surface morphology of the coatings. The application properties of such coating materials for the protection of buildings were tested, based on studies of their water vapor permeability, water absorption, and weathering resistance (freezing/thawing, salt-saturated aqueous sodium sulfate solution). The effect of the chemical structure of the siloxane-containing polymer matrix on the properties of the resulting coatings was focused on the protection of porous building materials. A very good correlation of the application properties of these coating materials and their surface properties, such as high dynamic contact angle (DCA), low surface-free energy (SFE) and surface morphology, was observed and is discussed.

Using Low-Field NMR to Determine Wettability of, and Monitor Fluid Uptake in, Coated and Uncoated Sands

Abstract Methods commonly used to measure the wettability of unconsolidated porous media are quick and easy to perform, but these tests do not provide reproducible results. This paper outlines the use of low-field nuclear magnetic resonance (NMR) as an alternative method of wettability assessment due to this tool's ability to discriminate bound fluid from bulk fluid. Water bound to the grain surfaces of water-wet samples relaxes quickly and produces signal amplitude peaks at low transverse relaxation (T2) values. Bulk water, on the other hand, relaxes much more slowly and signal amplitude peaks consequently appear at higher T2 values. It is expected that the contribution of surface-bound water in water-repellent samples is lower than in water-wet samples. NMR measurements performed on water-wet sand and on the same sand coated with organic matter clearly show significant differences in solid-fluid interactions between water and sands of different wettabilities. Numerous NMR measurements were obtained over time to monitor relaxation shifts because it was expected that the resulting spectra would provide insight into the rate of fluid uptake in sands of varying wettability. Water uptake appears to be spontaneous in water-wet samples and much slower in water-repellent samples, however all samples will eventually reach the same equilibrium endpoint regardless of wettability. NMR spectra also show that the results from water in uncoated and coated sands closely resemble that from water in wettable and water-repellent soils. Consequently, uncoated and coated sands can be used to analyze wettability mechanisms in unconsolidated porous media. The results also show that causative agents of soil water repellency include asphaltenes that are insoluble to n-pentane. Introduction Wettability is defined as "the tendency of one fluid to spread on or adhere to a solid surface in the presence of other immiscible fluids(1)." This parameter is not a fixed and constant property(2) due to factors such as saturation and climate history, as well as sample handling(3). Wetting and non-wetting fluids interact with a porous medium differently and these differences can be detected by low-field nuclear magnetic resonance (NMR)(4–6). One can infer the state of fluids within a porous medium from looking at NMR spectra based on type-specific transverse relaxation time (T2) cutoffs(7–9). Relaxation time is the time that a hydrogen-bearing molecule needs to revert to its original state, after it is excited by an oscillating magnetic field pulse sequence. Contributions to spectra at values of T2 that are lower than the cutoff are considered due to bound water while contributions at higher T2 values are considered due to water in the bulk phase(7, 10). Amplitude peaks at progressively lower T2 values indicate the presence of fluid in progressively smaller pores. The location of the amplitude peaks in NMR spectra can be used to infer sample wettability(9). While this has been done in porous media such as sandstones, carbonates, and chalk(11–14), no work has been done on soils. NMR can be a viable tool for assessing soils wettability because other wettability measurements such as the contact angle are impossible to make in unconsolidated porous media.

Surface treatment of carbon/epoxy and glass/epoxy composites with an excimer laser beam

The use of an excimer laser treatment, as a way to control the adhesion performances of glass/epoxy and carbon/epoxy composites has been investigated. Such a specific surface treatment can provide a selective removal of the organic matrix without any degradation of fibre reinforcements. Then, the influence of such treatments has been studied through surface roughness, wettability assessment and ESCA analysis. The use of two different adhesives in association with different surface treatments allows drawing some conclusions on the role and potential interest of surface cleaning and fibre protruding on the adhesion behaviour of resulting composite surfaces.