Papers by Keyword: Surface Energy

Abstract: Asphalt pavement performance is based on several parameters and properties of the materials’ element. surface free energy that the modifier and the asphalt binder both displays. The resistance of the modified asphalt binder to stresses and moisture damage is largely determined by the bond energies. Asphalt binder qualities may be altered by either technical or natural processes, which subsequently impact on the chemical and mechanical characteristics. In addition, a correlated investigation revealed that surface free energy values may be used to assess the compatibility of a binder in relation to moisture-induced damage. Data demonstrates that the incorporation of soft clay into the asphalt binder resulted in a favorable coating and bonding capacity, as compared to the control asphalt binder. moisture-induced damage in HMA is a combined effect of loss of cohesion of asphalt binder and loss of adhesion between asphalt binder and aggregate. It was indicated that the modified binders of BPSC ratios would delay and weaken the oxidation reaction asphalt binder which can enhance the aging process. Based on absorbance peaks of carbonyl and sulfoxide bonds, the addition of BPSC would delay the aging process of asphalt binder.

Abstract: Hastelloy is a nickel-chromium-molybdenum-iron-based alloy and a member of the ‘superalloy’ family. Hastelloy has exceptional properties like high strength, wear resistance and high-temperature stress-corrosion resistance. Therefore, Hastelloy is used in gas turbines, power plants, metal injection molding, etc. Many industrial applications are related to the properties of the surface. Wettability is a key surface property that affects applications like lubrication, adhesion, coating, heat conduction, etc. Laser Texturing is an excellent method to modify the surface properties of materials like metal, polymers and ceramic. In the present study, a carbon dioxide laser created unidirectional textures on Hastelloy (C22, C276, X). Different sets of unidirectional textures were formed by changing the laser power and frequency. Various roughness parameters were compared for every laser parameter. In this paper, the effective change in wettability properties of Hastelloy (C22, C276, X) after the Laser texturing process for a range of power and frequency were studied under DI water and glycerol as test fluids. Results show that the contact angle of the test fluid increases as the laser power increases, and the contact angle decreases as the laser frequency increases for all three superalloys. The surface energy of a given set of samples was also measured using the recorded contact angle of DI water and Glycerol by the OWRK equation. Similar trends were found in surface energy for all three Hastelloy.

Abstract: New tissue-engineered vascular prostheses of small diameter (4mm) based on biodegradable polymer backbone – poly (ε-caprolactone) (PCL) and its composition with poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV/ PCL) were created. The full cycle of surface modification of the backbone with polyvinylpyrrolidone and drugs permitted to increase significantly the atrombogenic and antimicrobial properties of prostheses and provide its effective matrix properties. Both types of the developed constructs are suitable for testing in vivo. The energy characteristics of the prosthesis surfaces at the different interfaces were determined. It was established that the value of the energy of the "polymer, saturated with octane/water" interface can be used as a parameter for predicting cell adhesion and proliferation in the case when it is difficult to determine or to distinguish the energy characteristics of the surfaces of tissue-engineered materials at the interface with air.

Abstract: Information on the effect of organosilicon liquid on the hydrophobic properties of coatings, based on acrylic resin, is presented. It is shown that the value of the contact angle on the anti-icing coating is 151-154 degrees. When moistened for 72 hours, a decrease in the value of the contact angle, especially on the control coating, is 81-103 degrees. However, at the introduction of liquid 136-41, a decrease in the contact angle is insignificant. The surface energy of the coatings was calculated. It was found that the introduction of an organosilicon liquid in an acrylic composition increases the surface energy of the coatings.

Abstract: Aspects of increasing the strength of silumin due to the introduction of ultrafine silica powders into its melt are considered. The calculation of the surface energy of silicon oxide nanoparticles showed the promise of this modification. The method is proposed for increasing the adhesion of silicon to aluminum, due to the surface-active properties of magnesium and the high surface energy of nanoparticles, which contributes to the formation of chemical compounds of silicon with aluminum, and as a result, to hardening of the alloy. Due to the large difference in the surface energies of magnesium and silicon, the possibility of producing Si @ Mg core-shell nanoparticles in the one-step method under the action of an electron beam has been shown. The layout of substances in the graphite crucible, the dependence of the electron beam current to obtain Si @ Mg nanoparticles are presented.

Abstract: This work was aimed to investigate the effect of alkalization treatment on the fiber-matrix interfacial interaction and hence their compatibility. Kenaf fiber was treated using a 6% NaOH solution for 8 hours. The composites were produced by mixing the treated fiber with PP at various temperatures, duration, and fiber composition. Alteration on the surface chemistry of the fiber was identified by performing FTIR analysis. The surface energy of the treated fiber was mathematically derived from the contact angle measurement results. The compatibility level between treated fiber and PP matrix was visualized through FESEM analysis. Tensile strength tests were also conducted to obtain data necessary for exploring the relationship between the thermodynamic aspects of the fiber-matrix interfacial interaction and the mechanical properties of the composites. The FTIR spectra show that there was significant increase in the %transmittance at wavelength range of 3100-3600 cm^-1 indicating that O-H groups were degraded during treatment. However, the polar component of the surface energy for treated fiber was instead higher compared to the untreated one. The SEM images show that there are no noticeable reduction in the size of the treated fibers as expected. On the other hand, the tensile strength of the PP-treated fibers composites reached its highest value when the matrix were loaded with fibers at the lowest percentage i.e. 5%.

Abstract: The article deals with the mechanism of interaction of super-plasticizers and hyper-plasticizers additives with mixing water, the formation of micelles and organized water. The interaction of mixing water and additives with Portland cement particles, surface tension, specific surface of bindings and their significance in setting and hardening processes are considered. It is shown that a local effect plays a decisive role in micro-heterogeneous organized media associated with the dissolution of hydrophilic and hydrophobic molecules in the volume of the micellar system or the receptor molecule cavity. In this case, the change of dissolved substances properties is due to the change of the medium state only in the microenvironment, and not in the whole solvent - water. The surface energy of the dispersed material and the degree of dispersion are very important for the concrete technology. All dispersed materials of the system are unstable. The aggregation of powder particles of building materials spontaneously takes place in highly dispersed powders and if such powders get pressure, it is possible to get a hard and strong material without water and additives.

Abstract: The protection of building structures and elements from the effects of moisture is currently a topical and discussed topic and this issue is also related to development of hydrophobized ceramic masonry elements with reduced water absorption.The quality and efficiency of the hydrophobic treatment is assessed primarily by monitoring the capillary absorption of the hydrophobized ceramic body and reducing the capillary conductivity (reducing the capillary elevation of moisture).The paper focuses on the more detailed physical study of the hydrophobic treatment of ceramic masonry blocks using laboratory methods, in particular the measurement of the contact angle and surface energy. With these measurements, it is possible to precisely specify the surface properties of individual ceramic masonry elements treated by hydrophobic treatment and thus accurately express the quality of the surface treatment. Based on the results was determined the dependence between capillary absorption and surface energy.

Abstract: Economically viable and maintenance free glass surfaces with improved hydrophobicity are highly demanding in the recent nanotechnology era. Deposition of pollutants and dirt on glass surface that not only causes visual obscurity but also damages the cultural heritages are still to be researched intensely. It is documented that excellent hydrophobic surfaces (with contact angle greater than 90^o) can be achieved by controlling the surface wettability, where liquid droplets remain spherical on such surfaces. Selection of materials and the preparation method play a significant role towards such accomplishments. Stirred by this idea, we explored the feasibility of fabricating super-hydrophobic tellurite glass systems by facilely varying the compositions of different constituents. Highly transparent and thermally stable ternary tellurite glass system with chemical composition of (80-x)TeO₂ – xSiO₂ – 20ZnO, where x = 0.00 to 0.20 mol% are synthesized via conventional melt-quenching method. Samples are characterized using Atomic Force Microscopy (AFM) and contact angle measurements. The impact of SiO₂ concentrations variation on the surface roughness, surface energy, and hydrophobic properties are inspected. Glass surface roughness as much as 9.885 nm is attained. The optimal value of water contact angle is discerned to be 101.02° for 0.1 mol% of SiO₂ incorporation into the amorphous tellurite host matrix. Besides, the surface energy revealed an inverse proportionality to the water contact angle. This achieved contact angle (greater than 90°) makes this hydrophobic glass surface beneficial for diverse applications. It is established that the present glass composition may be prospective for the development of super-hydrophobic surfaces.

Abstract: Recently, we have reported on low friction CrN/TiN coatings deposited using a hybrid sputtering technique. These multilayers exhibit friction coefficients μ below 0.1 when tested in atmosphere with a relative humidity ≈ 25 %, but μ ranges between 0.6–0.8 upon decreasing the humidity below 5 %. Here we use first principle calculations to study O and H adatom energetics on TiN and CrN (001) surfaces. The diffusional barrier of H on TiN(001) is about half of the value on CrN(001) surface, while both elements are stronger bonded on CrN. Based on these results we propose a mechanism for a water-based self-assembled nanobearing.