Contact Angle Method Research Articles

The effects of polymer modified asphalt binder incorporating with chemical warm mix additive towards water quality degradation

Naturally, asphalt binder has compacting and mixing temperatures higher than 150 °C. Both temperatures can be increased by modifying the pristine penetration grade asphalt binder with polymer. However, the warm-mix asphalt (WMA) technology contributes to lowering of these temperatures even though the possibility of environmental effect cannot be neglected. Air pollution and water contamination are two crucial environmental concerns when it comes to chemical reactions of any materials. This study was conducted to investigate the physical characteristics, thermal analysis, leaching and toxicity of polymer-modified asphalt binder (PMA, PG76) and its performance as the binding agent. Physical tests were carried out to determine the durability, quality and performance of PG76 binder. Thermal analysis via thermogravimetry analysis was carried out to observe the stability of the blending at higher temperature. The results illustrated that even though the PMA is added in combination with WMA as additives, the mixes were stable beyond their mixing and compaction temperatures. The decomposition started at temperature >360 °C and ended at temperature <500 °C for all samples. Wetting and spreading behaviours of the blending are also perceived by contact angle method. Increasing amount of WMA allowed the spreading of water on the surface. The surface was deemed to be hydrophilic or poorly hydrophobic. Leaching Tank Test was carried out to simulate water suspension during heavy rainfall and its influence in leaching traces of heavy metal from asphaltic binders. The tests were carried out at 0.25, 1, 2.25, 4, 9, 16, 36, and 64 days to observe the leaching behaviour of heavy metals and determine the toxicity of the samples. Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was used to detect the presence of heavy metals (Cu, Zn, Ni, Pb, Cr and Fe) and the readings were analysed to Heavy Metal Evaluation index (HEI), Heavy Metal Pollution Index (HPI), Degree of Contamination (Cd), and Metal Quality Index (MQI). The cumulative values of heavy metals are presented in the form of logarithmic graphs. All indices indicated that all samples did not contribute to heavy metal pollution to the surrounding water resources.

Synthesis of Graphene Oxide Using Atmospheric Plasma for Prospective Biological Applications.

IntroductionThis paper presents a novel technique for the synthesis of graphene oxide (GO) with various surface features using high-density atmospheric plasma deposition. Furthermore, to investigate the use of hydrophobic, super-hydrophobic, and hydrophilic graphene in biological applications, we synthesized hydrophobic, super-hydrophobic, and hydrophilic graphene oxides by additional heat treatment and argon plasma treatment, respectively. In contrast to conventional fabrication procedures, reduced graphene oxide (rGO) formed under low pressure and high-temperature environment using a new synthesis method—developed and described in this study—offers a convenient deposition method on any kind surface with controlled wettability.MethodsHigh density at atmospheric plasma is used for the synthesis of rGO and GO and its biocompatibility based on various wetting properties was evaluated using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, and the viability of cells in response to rGO and GO with various surface features was investigated. Structural integrity was characterized by Raman spectroscopy, FESEM and FE-TEM. Wettability was measured via contact angle method and confirmed with XPS analysis.ResultsWe found that GO coating with a hydrophilic feature is more biocompatible than other surfaces as observed in case of fibroblast cells. We have shown that wettability—controlled by GO deposition—influences biocompatibilities and antibacterial effect of biomaterial surfaces.DiscussionMeasuring the contact angle, it is found that contact angle for hydrophobic is increased to 150.590 and reduced to 11.580 by heat and argon plasma treatment, respectively, from 75.880 that was initially in the case of hydrophobic surface. XPS analysis confirmed various oxygen-containing functional groups transforming as deposited hydrophobic surface into superhydrophobic and hydrophilic surface. Thus, we have proposed a new, direct, cost-effective, and highly productive method for the synthesis of rGO and GO—with various surface properties—for biological applications. Similarly, for the dental implant application, the Streptococcus mutans was used as an antibacterial effect and found that S. mutans grows slowly on hydrophilic surface. Thus, antibacterial effect was prominent on GO with hydrophilic surface.

Transparent and Self‐Cleaning Surfaces Based on Nanocomposite Sol‐Gel Coatings

AbstractIn this study, transparent anti‐fogging and self‐cleaning nanocomposite coatings based on sponge‐like TiO2−SiO2 nanoparticles on glass substrate were prepared through the sol‐gel process, by using spin‐coating and spray gun techniques to coat small and large glass surfaces. The effect of annealing temperature on the morphology, wettability, UV–Vis transmittance, refractive index, thickness, photocatalytic degradation rate and the anti‐fouling effect was studied in detail. Indeed, the self‐cleaning properties of the nanocomposite coatings were evaluated as efficient by both photocatalytic degradation of orange G (OG) dye under natural sunlight irradiation and water contact angle (WCA) method under atmospheric out‐door conditions. It should be noted that the optical transmission of nanocomposite coatings remains important (85–87 %) compared to the ordinary glass (92 %) with lower haze value, which confirms their clear optical appearance. The nanocomposite coatings rendered the glass substrate hydrophilic with a WCA value that not exceeding 12° after fifteen weeks of out‐door exposure. Photocatalytic degradation rate relative to OG up to 7.9 % were achieved for the nanocomposite coating annealed at 500 °C after 8 hours of sunlight exposition. The soil attachment test reveal that nanocomposite coatings prevent the accumulation of soil particles and has an excellent anti‐fouling and anti‐fogging properties. These findings indicated that the TiO2‐SiO2 nanocomposite coatings could be a very attractive solution for many practical areas (environment, energy and building sectors) especially for outdoor applications.

A comparison and correlation between bitumen adhesion evaluation test methods, boiling and contact angle tests

Road pavement is principally made of mineral aggregates and a bitumen binder. Aggregates, due to their mineralogical nature, have complex chemical compositions and physical properties, which are strongly dependent on the minerals that constitute the stones. In pavement technology, bitumen/aggregate affinity is of paramount importance. Moisture damage in hot mix asphalt (HMA) is one of the major concerns in durability of flexible pavements, to improve the adhesion between the bitumen and the stones and increase the life of the road pavements often it is necessary using additives as the antistripping agents. Currently, there are several techniques such as the Boiling Test, the Rolling Bottle Test (RBT), etc., which evaluate the adhesion between the bitumen and the stones, however, most of them are based on a subjective evaluation. In the present paper, several types of mineral aggregates are characterized in detail by optical microscopy (OM) and X-ray powder diffraction (XRPD) in order to correlate the Boiling Test and the contact angle method to investigate the level of bitumen/aggregate affinity. For this reason, a single type of modified bitumen and two adhesion promoters were studied.The obtained results show the reliability of the technique used. However, there are still some limitations regarding the use of a contact angle test in assessing bitumen/aggregate affinity.

Hydrophobizing polyether sulfone membrane by sol-gel for water desalination using air gap membrane distillation

ABSTRACT The hydrophobic polyether sulfone membranes were prepared by the sol-gel method to be applied in an air gap membrane distillation setup for desalination. The surface modifications were carried out using Trimethylsilyl chloride (TMSCl) and Methyltrimethoxysilane (MTMS) solutions. The membranes were characterized using Attenuated Total Reflection Infrared (ATR-IR) spectroscopy, Scanning Electron Microscopy (SEM), and Optical Contact Angle (OCA) methods. The effects of membrane preparation as well as operating conditions such as temperature difference, salt concentration, feed rotation speed, and cold-side temperature on membrane performance were investigated using central composite design method. It was found that feed temperature has the largest effect among the parameters on the permeation flux. The flow rate and salt rejection of the membrane in the optimum conditions were 4.47 Kg m−2 h−1 and 99.37%, respectively.

Laser treatment of SiAlON and surface characteristics

Laser treatment of SiAlON surface is considered and characteristics of the resulting surfaces are studied incorporating the scanning electron and atomic force miscroscopes, X-ray diffraction and Fourier transform infrared spectroscopy. The wetting state of the laser treated surface is assessed using the droplet contact angle method while the friction coefficient of the treated surface is obtained by using the micro-tribometer. Microhardness and fracture toughness of the treated surface are also measured. Thermal and thermal stress analyses are carried out and temperature and von Mises stress fields are predicted in the laser treated region. It is found that in micro/nano size pillars are formed on the laser treated surfaces, which alters the wetting state from hydrophilic to hydrophobic with contact angle 120° and contact angle hysteresis in the order of 18.2°. In general, laser treated surface is free from large size cracks and voids; however, few locally scattered micro-cracks are observed on the surface. Microhardness increases slightly for the laser treated surface because of the dense layer formed on the surface under the high cooling rates. The fracture toughness of the surface reduces slightly and the friction coefficient of the surface improves after the laser treatment process. The laser scanning tracks, which are closely spaced, result in self-annealing effects in the laser treated region; in which case, von Mises attains low values particularly along the recently formed laser scanning tracks.

Application of polymeric nanofluid in enhancing oil recovery at reservoir condition

In this study, ascorbic acid was used to synthesize Cissus populnea nanoparticles (CPNP). The synthesized CPNP was isolated and the influence of the process variables on the physical properties were studied. The rheology of the formulated Cissus populnea nanofluid (CPNF) was measured and compared with Cissus populnea (CP) solution and commercial polymer xanthan. Moreover, the interfacial properties of CPNF were studied at various concentrations and temperatures, and the influence of salinity and their interaction with ultrasound was investigated. Sessile drop contact angle method was used to determine the wettability alteration efficiency of CPNF on an initially oil-wet sandstone core surface. Finally, CPNF and CP solutions were evaluated for EOR purposes at typical reservoir condition. The displacement process was scaled to reduce the number of parameters investigated using dimensionless parameters. The synthesis methods were efficient in generating sphere-shaped and elongated nanoparticles (50 nm mean diameter). Experimental results show that an increase in temperature of CP and CPNP yielded increased viscosity of the solutions in stark contrast to xanthan whose solution viscosity declines as the temperature increases. Besides, the CPNF was effective in lowering IFT at oil-water (O/W) interface and altered the wettability of the sandstone cores to water-wetting condition. The novel CPNF increased the oil recovery by 26% and was effective at high-temperature high-pressure (HTHP) reservoir condition. The result shows a transition from capillary dominated flow to gravity dominated flow as decrease in IFT decreased residual oil saturation and increased capillary and Bond number. The energy consumption and cost estimation of the proposed novel polymeric nanofluid shows it is cost-effective than conventional EOR chemicals.

Sandblasting parameter variation effect on galvanized steel surface chemical composition, roughness and free energy

The aim of this paper is to investigate the effect of variant sandblasting parameters such as pressure, angle and sand granulometry on galvanized steel surface chemical composition, roughness and free energy for the purpose of increasing its adhesion properties for further use in structural bonding applications. Two sandblasting pressures (5 × 105 Pa, 6 × 105 Pa), two sandblasting angles (75°, 90°), and three glace sand granulometries (200/300, 90/150, 70/110) were tested. Surface chemical composition was evaluated using a scanning electron microscope, surface roughness was measured using a mechanical surfscan and surface free energy was determined using the contact angle method along with the two component Owens-Wendt model. Trials revealed that the sandblasting method has an effect on the surface free energy, wettability, chemical composition and roughness. As the sandblasting pressure and glace sand granulometry increased, the surface average roughness (Ra) increased. Specimens treated with the lowest glace sand granulometry had the highest surface free energy (γst). Glace sand granulometry had a more significant effect on the galvanized steel surface properties than that of the sandblasting pressure and angle. Sandblasting angle variation affected the surface chemical composition and wettability rather than the roughness. Sand residue presented at the level of the treated surface varied according to the sandblasting setting which might have affected the surface free energy and wettability along with the roughness.

Mechanism of the Wettability Impact on Surfactant Imbibition in Dodecane-Saturated Tight Sandstone

As a result of low porosity and low permeability in tight reservoirs, spontaneous imbibition plays an important role in oil recovery. While wettability has a crucial impact on the imbibition, the mechanism of the effect of wettability on imbibition is still unclear. In this study, we screened the surfactants with similar interfacial tension (IFT) at the same concentration to study the wettability properties, which will contribute to improve the oil recovery tight reservoir. Two betaine surfactants, lauramide propyl hydroxysulfonated betaine (LHSB) and cocamidopropyl betaine (CAB), were screened according to their IFT. Through spontaneous imbibition experiments, the recovery of LHSB (27.26%) was better than that of CAB (21.69%). The contact angle method and U.S. Bureau of Mines method were used to analyze the core wettability comprehensively. After LHSB treatment, the core wettability index turned to hydrophobic and the wettability index changed from −0.06 to −0.56. However, the wettability index did not change significantly after CAB treatment (−0.15). Further molecular simulations showed that, after the surface of the rock is modified by LHSB, the oil droplets spread gradually and the interface energy with the quartz was enhanced. In combination of the analysis of the ζ potential and adsorption measurement, LHSB is predicted to be adsorbed in a single-layer configuration, while CAB formed a double-layer configuration, which caused the difference in wettability. It can be speculated that, when the surfactant changes the pore surface of the tight sample toward hydrophobic, the oil-wet surface promotes the residual oil droplets to form a continuous phase and, at the same time, reduces flow resistance of the water phase, thereby increasing the spontaneous imbibition rate and the ultimate recovery. This study will help to understand the wettability impact on imbibition by the surfactant and contribute to the improvement of tight oil reservoir recovery.

Effect of fiber length and surface treatment on the performance of fiber-modified binder

In this study, the effects of fiber lengths and surface treatments of aramid fibers on the performance of aramid fiber-modified asphalt (AFMA) binders were examined. The surface treatment effects of aramid fibers with the silane coupling agent 3-methacryloxypropyltrimethoxysilane (KH-570) were investigated using scanning electron microscopy, a static contact angle method, and Fourier transform infrared spectroscopy. The length effects of the aramid fibers on the asphalt performance were studied using a dynamic shear rheometer, viscometer, and bending beam rheometer, and the improvement mechanisms were analyzed. The results show that an increase in fiber length can improve the viscosity of AFMA, and a reinforcement effect from short fibers with high content can be achieved by using long fibers with low content. It also indicated the silane coupling agent can enhance the bonding effect of fiber and asphalt. The results of this study can provide a reference for the application of fibers in asphalt binders and asphalt mixtures.

Effect of preparation methods of graphene oxide on permeability of free-standing membranes against polar and nonpolar species

ABSTRACT In this study, graphene oxide (GO) was synthesized using Hummers, modified Hummers and improved Hummers methods, and then freestanding membranes were prepared based on these materials. Effects of different GO preparation methods on C/O ratio and interlayer spacing of freestanding membranes were studied. Structure of these membranes was studied by X-ray diffraction, contact angle, XRF, FT-IR, and FESEM methods. Also, permeability of ammonia, dichloromethane, and water vapor was investigated through these membranes. Results showed that, the sample prepared by the Hummers method had lower C/O ratio, smoother surface and lower permeability for polar species, such as water and ammonia vapors, than nonpolar materials. Membranes prepared using Improved Hummers method showed the least permeability against nonpolar vapors such as dichloromethane.

Assessment of spring waters from Lourdes (France) by contact angle method

The geochemical investigations on karst spring waters in the area of Lourdes showed differences between the waters for numerous components, including main solutes and trace elements. In this study, a multidisciplinary approach was proposed, based on the surface free energy of solids and the surface tension of liquids using the contact angle method, by raising the hypothesis that different spring waters diverge in surface tension characteristics, which allow to discriminate waters origin in a natural system. Surface energy characteristics of spring waters from Batsurguère Valley were investigated here using the contact angle measured over time and the tangent method in relation to the variations of the droplet volume. Wettability of various test solids was analyzed using static and kinetic contact angle methods which led to the individuation of the spring waters on the base of the different adhesion processes occurring at the interface between water and solid, particularly on the silica glass solid. The analyses demonstrated that the surface tensiometry technique can discriminate one of such spring waters (i.e. the Massabielle spring) from other studied spring waters, regardless of their natural hydrological conditions. Contact angle hysteresis in kinetic modality, based on several repeated and extemporary set of experiment determinations, suggested a link between the water chemistry and the wettability over time of the test solids, confirming that chemical composition has an influence on the surface tension of spring waters. This investigation demonstrates that the surface tensiometry approach may represent a useful tool for monitoring quality of natural waters.

Rapid homogenization preparation of the mussel‐inspired hydrophilic separator for high power lithium‐ion batteries

AbstractIn this work, a thin and smooth PEI/Dopamine coating layer was immobilized onto the PP separator skeleton via co‐deposition of dopamine and polyethyleneimine (PEI, 600 Da). The PEI/Dopamine decorated separator was characterized by SEM, FT‐IR/ATR, XPS, UV, EDX, DSC, contact angle and electrochemical methods. The PEI/Dopamine decorated separator showed stable thermal performance. The pure water contact angle was reduced after PEI/Dopamine coating modification. The electrolyte uptake was improved by reason of the boosted compatibility between separator and liquid electrolyte. Meanwhile, the high absorption rate of electrolytes and the introduction of polar functional groups promote the desolvation of lithium ions and the dissociation of lithium salts, thereby improving the ionic conductivity. Batteries assembled with PEI/Dopamine decorated separator displayed more stable cycle performance and the C‐rate performance was greatly enhanced. These results demonstrate that PEI/Dopamine decorated separator is expected to be an ideal choice for high power lithium‐ion batteries.

An undamped oscillation model with two different contact angles for a spherical droplet impacting on solid surface

Предложен нелинейный подход описания колебания сферической капли на твердой поверхности. Интегрирование уравнений движений осуществляется без использования линеаризации тригонометрических функций, зависящих от угла контакта. Иными словами, угол контакта является произвольной конечной величиной. Проведено исследование влияние силы тяжести на угол контакта и радиус распространения капли по твердой поверхности. Таким образом, было найдено нелинейное уравнение, описывающее изменение радиуса распространения капли в зависимости от времени. Данное уравнение было численно проинтегрировано. Исследование численной сходимости осуществлялось посредством сравнения с известными модельными точными решениями и известными экспериментальными данными. На основании исследования методами численного интегрирования полученного в статье уравнения можно сделать вывод о целесообразности использования математической модели для описания и исследования новых физических эффектов при колебании капель.

SnO2:PANI modified cathode for performance enhancement of air-cathode microbial fuel cell

SnO2:PANI composites were synthesized and used as cathode material to enhance oxygen reduction reaction (ORR) in an air-cathode microbial fuel cell (MFC). The ratios of SnO2:PANI composites were varied as 50:50 (5S:5 P), 40:60 (4S:6 P), 30:70 (3S:7 P), SnO2 (S:0), and PANI (0:P). Analytical techniques were used for physical characterization of composites Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Dynamic light scattering (DLS), and Transmission electron microscopy (TEM). Water uptake and wettability of electrodes were evaluated using contact angle method. It was found that coating improves the hydrophobicity of the electrode. Cyclic voltammetry (CV) showed that the modified electrode had moderate capacitance and Electrochemical impedance spectroscopy (EIS) revealed a reduction in internal resistance due to the modification of the electrode. Tafel analysis showed that the relative kinetic activity of the electrodes having 4S:6 P weight ratio was nearly 102 times more than that of the bare electrode. The highest power density of 65 mW m−2, which is nearly two times that of carbon felt, was obtained by the reactor containing 4S:6 P composite coated cathode. The results revealed that the 4S:6 P composite can be a promising option as a cathode catalyst for enhancing the performance of MFCs.

Properties of hydrophobic carbon–PTFE composite coating with high corrosion resistance by facile preparation on pure Ti

Abstract Composite coatings consisting of carbon and polytetrafluoroethylene (PTFE) were prepared on Ti alloy substrate by a simple two-step process of hydrothermal and impregnation. The morphology, composition, hydrophobic and corrosion properties of the composite coatings were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), water contact angle method, X-ray photoelectron spectroscopy (XPS) and electrochemical technique, respectively. The effect of PTFE content on the corrosion properties of the composite coatings was studied. It is found that the composite coating film exhibits a full coverage with uniformly distributed PTFE when 0.1 mol/L of glucose is used as carbon source and 20 wt.% PTFE suspension as impregnating solution. The coating with 20 wt.% PTFE has a good bonding strength with Ti plate and exhibits excellent hydrophobic property with a water contact angle of 142.3° as well as superior corrosion resistance with corrosion current density as low as 0.0045 µA/cm2. With regard to its excellent hydrophobicity and corrosion resistance, the carbon–PTFE composite coating may find potential application in automobiles and metal corrosion industries.

Azithromycin-Chitosan Films for Improved Haemostasis and Wound Healing

Wound healing is a global medical concern, because haemorrhage is still a major cause of morbidity and mortality. Therefore, more effective and cost-effective dressings are required. Antimicrobial dressing of Azithromycin (AZM) (a broad-spectrum macrolide antibiotic) with Chitosan (CS) as a carrier, has a lot of desired properties such as haemostatic, pain-reducing, and less scar forming. It is prepared by a solvent evaporation method. The film morphology is investigated by SEM and film-water wettability is measured by a contact angle method. The drug-polymer interactions are evaluated by using FTIR and DSC. Azithromycin loaded films (different mass ratio of AZM to CS w % 10%, 25% and 50%) were sterilized by Gamma radiation, then their antimicrobial characteristics and haemostatic performance were evaluated. Film thickness was about 9 µm. The wettability properties of films were enhanced by adding AZM and PEG6000 5% (mass ratio of PEG 6000 to CS w %). Microbial growth inhibitions were identified for films loaded with Azithromycin.

Water repellent finishing on eri silk fabric using nano silica

Nano silica was extracted from rice husk and applied on eri silk fabric to impart water repellency. The efficiency of the water repellency was evaluated with water contact angle, water absorbency and spray test methods. In order to enhance the water repellent properties, a silicone-based polymer was also applied. The effect of nano silica coating on the physico-mechanical properties of the eri silk fabric was studied using standard methods. SEM, FTIR and EDX techniques were used for the confirmation of presence of nano silica on silk fabric. The results inferred the nano silica imparted hydropholic property to eri silk fabric, which was further enhanced to superhydrophobic by the incorporation of silica polymer. The nano silica coating slightly enhanced the whiteness and brightness of eri silk fabric. Other mechanical parameters like bending rigidity and crease recovery angle were found to be intact. The higher concentration of nano silica caused a slight reduction in fabric tensile strength.

Antibacterial and antioxidant assessment of cellulose acetate/polycaprolactone nanofibrous mats impregnated with propolis

Cellulose acetate (CA) electrospun nanofibers are one of the most practical cellulosic material which normally applied as carriers for drug delivery and wound healing systems. In this study, CA and polycaprolactone (PCL) was applied to fabricate the electrospun nanofibrous for wound dressing application. Propolis is a resin-like macromolecule produced by honeybees from the buds and diverse plants. Among many applications of this macromolecule, it has been occasionally employed directly to the skin for wound healing applications. Herein, owing to the significance of propolis, CA/PCL nanofibers were impregnated with a propolis-extracted solution to reach antibacterial and antioxidant mat. The scanning electron microscopy (SEM) images revealed that electrospinning of 10% (w/w) CA along with 14% (w/w) PCL produced excellent nanofibers compared to the resultant nanofibers. Hydrophobicity/hydrophilicity nature of CA/PCL mats was measured using water contact-angle method before and after treatment with NaOH. The nanofibrous mats exhibited a high water absorption capacity of about 400%. Antioxidant effect was measured by 2,2-Diphenyl-1-picrylhydrazyl (DPPH) assay and propolis-CA/PCL presented a high antioxidant activity. Additionally, propolis-CA/PCL mats showed antibacterial activity against both the Gram-positive and Gram-negative bacteria. In conclusion, our results have confirmed that the propolis-impregnated CA/PCL mats have provided an appropriate surface for wound healing system.

Surface decomposition and registration efficiency of CR-39 detector irradiated by electron beam

Poly allyl diglycol carbonate (CR-39) solid-state nuclear track detector is irradiated by a low-energy electron beam, and the decomposition of the irradiated samples is inspected with various techniques. The CR-39 viscosity is tested and showed that the primary effect of irradiation is surface degradation. The surface etching at different irradiation fluence is studied and correlated to the modified surface morphology. Moreover, the changed surface chemical composition is explored by Raman spectroscopy, which shows changes in the polymer structure after treatment. The surface wettability is investigated by the contact angle method. Surface wettability, free energy and polarity increase after irradiation. The performance of irradiated CR-39 is tested for the detection of fission fragments from 252Cf radioactive source. It is found that etching sensitivity and detection efficiency are enhanced after irradiation. The induced changes due to electron beam irradiation are pronounced and improve the etching characteristics, which control the registration efficiency of the CR-39 detector.