Surface Energy Characteristics Research Articles

Interfacial strength and its regulation in the carbon monofiber/epoxy binder system

The strength of polymer composite materials (CMs) is largely determined by the strength of interfacial interactions at a fiber/matrix interface. In this work the strength in a unit cell of CM carbon monofiber/cured epoxy matrix is investigated. The relevance of the work is due to direct measurements of strength at the monofiber/matrix interface, excluding defects of micro-droplet and technological errors associated with impregnation in a traditional assessment of polymer composite materials strength. Changes of surface morphology and energy characteristics of fibers in plasma chemical treatment process is shown. The study of fiber surface energy and formation of carbon monofiber/epoxy matrix interface of carbon fiber reinforced composite unit cell was carried out on the specially developed original device Drop-Sting test. Micro pull-out test was used to investigate the shear mechanical properties of interface and to determine the strength of carbon fiber reinforced composite unit cells before and after treatment in oxygen discharge plasma. It is shown that the increase in the strength of the monofiber/matrix interfacial interface after the treatment of carbon fiber in plasma occurs due to the increase in the surface energy and wettability of monofibers.

Bilayer coating fabricated on aluminum alloy substrates with superamphiphobicity, corrosion resistance, self-cleaning, and delayed icing properties

To address the functional failure caused by low-surface-tension liquid wetting and adhesion in superhydrophobic materials, in this study, we constructed a bilayer coating with superamphiphobic properties using an epoxy (Ep) bonding layer and an organosilane-grafted attapulgite (OG-ATP) layer through spray-coating technique. The prepared superamphiphobic bilayer coating exhibited high contact angles (CAs) and low sliding angles (SAs) for cold water (25 °C), hot water (85 °C), glycerol, ethylene glycol, peanut oil, and even n-hexadecane (CA = 150.4 ± 0.3° and SA = 7 ± 2°) with surface tension of 27.5 mN m−1. Surface morphology and elemental analysis confirmed the coating's unique micro-nano hierarchical structure and low surface energy characteristics. Electrochemical impedance spectroscopy (EIS) results showed that the surface charge transfer resistance (Rct) and low-frequency modulus (|Z|0.01Hz) were enhanced by 6–7 orders of magnitude compared to the bare aluminum alloy substrate. The anti-corrosion performance remained stable even after 5 days of 3.5 wt% NaCl immersion. Additionally, icing experiments with water droplets at −10 °C and −15 °C revealed a significant delay in ice formation on the substrate protected by the bilayer coating. The development of this protective material, combining superamphiphobicity, self-cleaning, corrosion resistance, and anti-icing functions, will provide advanced technological reserves in areas such as marine, aviation, transportation, and manufacturing.

Effect of SiO2-H2O nanofluids on wettability of pulverized coal and the modification mechanism

To address the challenge induced by the hydrophobicity of coal dust, it is crucial to explore the impact of innovative wetting agents on the wettability of coal dust. In this regard, the present study focuses on SiO2-H2O nanofluids at four concentrations and pulverized coal with different particle sizes collected from different coal mines. The investigation focuses on the influence of SiO2-H2O nanofluids on the wettability of pulverized coal through an array of tests, encompassing surface tension assessments, viscosity measurements, contact angle analyses, reverse imbibition examinations, shooting of nanoparticle deposition patterns, and scanning electron microscopy. Furthermore, the underlying mechanism by which SiO2-H2O nanofluids enhance the wettability of pulverized coal was analyzed. The findings of the research reveal a substantial enhancement in the wettability of pulverized coal when modified with SiO2-H2O nanofluids. Specifically, when treated with nanofluids at a concentration of 1.5 wt%, the wettability improved by up to 44.61%, while the water absorption rate (WAR) increased by up to 4.82%. Notably, high-concentration nanofluids demonstrated effective suppression of coal dust with larger particle sizes, whereas low-concentration nanofluids addressed smaller particle sizes. SiO2 nanoparticles with high surface energy and robust adsorption characteristics, adhered to and agglomerated on the surface of pulverized coal, forming either globular or chained aggregates. This phenomenon emerged as the main cause for enhancing the wettability of pulverized coal. Finally, the study introduced a concept for an integrated technology aimed at controlling dust in mines, encompassing the preparation, transportation, and spraying of nanofluids. This research holds substantial theoretical and practical importance for the effective management of dust in coal mines.

Lubrication, wear resistance and corrosion protection on aluminum alloy toward multifunctional coatings with nano-CeO2 inhibition effect

The coupling effect of wear and corrosion aggravates the damage and failure of key moving parts of high-end equipment, leading to a significant reduction in their service life. In present work, a functional integrated composite coating with exceptional corrosion resistance and tribological properties was developed by utilizing the responsive corrosion inhibition of nano‑cerium oxide (nano-CeO2) and the low surface energy and low shear characteristics of polytetrafluoroethylene (PTFE). The tribological behaviors and corrosion protection performance of coatings on aluminum alloy 2024 were evaluated and the corrosion inhibition mechanism was further discussed. The results revealed that Ce3+ on the surface of nano-CeO2 reacts with OH− generated by the REDOX reaction of the cathode to produce a uniform and stable passivation film, which can effectively improve the corrosion resistance of the metal matrix. Notably, the most obvious passivation effect is presented when the 2 % addition of nano-CeO2 as the larger low-frequency impedance modulus of 4.49 × 1010 Ω·cm2 and higher phase angle of 88°. The introduction of PTFE not only changes the coating from hydrophilic to hydrophobic, but also further improves the shielding properties of the coating. The low-frequency impedance modulus of the coating further increases by an order of magnitude to 2.38 × 1011 Ω·cm2, and its neutral salt spray resistance exceeds 210 days. Besides, the friction coefficient is reduced by 77.43 % and the wear resistance improved by 6.8 times compared with phenolic epoxy coating. Due to the enhancement and corrosion inhibition effect of nano-CeO2, the lower friction coefficient (0.044) and good wear resistance are further presented under the corrosive medium condition of 3.5 % NaCl solution.

Preparation and Applications of Superhydrophobic Coatings on Aluminum Alloy Surface for Anti-Corrosion and Anti-Fouling: A Mini Review

Aluminum alloy is widely used in many fields for its excellent performance. However, in practical application, aluminum alloy is easy to become corroded and be invalidated, owing to the influence of environmental factors. Some pollutants or corrosive media on its surface adhesion will further deepen the failure rate of aluminum alloy, resulting in a large amount of workforce waste, waste of material and financial resources, and energy consumption. So the anti-corrosion and anti-fouling treatment of aluminum alloy surfaces to expand their practical application range and reduce energy loss are of great significance. In this paper, we first summarize the types of anti-corrosion and anti-fouling coatings on aluminum alloy surfaces. We found that superhydrophobic coating has attracted widespread attention recently because of its surface’s non-wetting and low surface energy characteristics. The superhydrophobic coating refers to a coating with a water contact angle on its surface greater than 150° and a sliding angle of less than 10°. Preparing superhydrophobic coatings on the surface of aluminum alloy can improve the corrosion resistance and anti-pollutant adhesion ability at the same time. Therefore, in the following part of the review, the preparation methods of superhydrophobic coatings on aluminum alloy surfaces for anti-corrosion and anti-fouling and the significant problems encountered in the practical application of the superhydrophobic coating on aluminum alloy surfaces, such as poor anti-corrosion durability and poor mechanical stability, and the existing methods to solve these critical problems, are summarized and discussed in detail. Finally, we put forward some new solutions to solve these vital issues.

Study of the surface energy characteristics of glass and carbon fiber by the Washburn method

The Washburne adsorption method (capillary rise method), as an alternative to the standard single fiber method, is proposed to investigate the surface energy characteristics of glass and carbon fibers using a K- 100 processor tensiometer. The paper considers sample preparation of fibrous materials measured by the Washburn method: filling a Teflon tube with glass and carbon fibers, packing density of the resulting capillary, and determination of the capillarity constant. The results of measurements of the wettability of fibers in test liquids (water, hexane) and in the solution epoxy binder UP-2227N are presented. The influence of appretting on the surface energy characteristics of glass fiber and carbon fiber was studied, a comparative analysis of the obtained values (wetting angle, SEP, adhesion) was carried out before and after the removal of lubricants.

Thermal and structural stability evolution of Ni@Pd and Co@Pd – Understanding from molecular dynamics simulations

Bimetallic nanoparticles are high performance materials for different fields as they can be constructed under different structures combining noble-metal nanoparticles which have been commonly used as catalysts for a variety of applications, to 3d-transition metals that have emerged as promising contenders for integration into high-performance noble-metal-based catalysts. In this study, we utilized molecular dynamics simulations to model a noble metal (Pd) and 3d-transition metals (Ni, Co), as core-shell and Janus nanoparticles to examine their thermal and structural properties. The heat of formation, melting point, surface energy, and diffusive physical characteristics are studied. The results reveal that the melting point for Co@Pd is higher than that of Ni@Pd, with the Janus nanoparticles having the larger melting points. However, Co@Pd NPs show a good stability for both structures. Based on all the observations made, it can be concluded that the thermal stability of the nanoparticles is significantly influenced by both the structure of their core and shell elements.

High contrast ratio and fast response ferroelectric liquid crystal displays based on alignment optimization

There are a series of polyimide material synthesized and studied with different dianhydride and diamine structures. By exploring the structural variations of these materials and their surface energy characteristics, we successfully obtained ferroelectric liquid crystal devices exhibiting exceptional optical and electrical properties. Notably, our findings highlight that a specific polyimide material comprised of dianhydride with a benzene ring structure and diamine with a long-chain amino structure demonstrates remarkable achievements, including a maximum contrast of 872 and a rapid response speed of less than 0.1 ms. These results establish the superiority of this particular polyimide material over its commercially available counterparts. Additionally, the optical characteristics of various polyimide materials were examined by establishing a correlation between these properties and the surface energy of the materials. This research presents a novel approach to developing alignment materials suitable for ferroelectric liquid crystal applications. The implications of our findings are of great significance in driving advancements in field-sequential-color display devices with high pixels per inch in the ferroelectric liquid crystal field.

Evolution of the surface energy of BaTiO3 nanoparticles in the course of dispersant coating: An inverse gas chromatography study

Understanding the surface energy characteristics of nanoparticles is crucial for controlling their stability, dispersion, and subsequent material properties. In this study, we employed inverse gas chromatography (IGC) to investigate the changes in surface energy and its homogeneity of BaTiO3 nanoparticles during coating with a model dispersant, stearic acid (SA), at various coverage levels. The IGC results revealed that the SA coating led to a more stable and homogeneous dispersive surface energy, enhancing the overall stability of the nanoparticles. However, it also introduced heterogeneity in the specific surface energy, with a notable shift towards higher levels. The observed evolution of surface energy characteristics was consistent with trends of the adlayer formation as determined through conventional surface characterization techniques, including thermogravimetric analysis-gas chromatography mass spectrometry and diffuse reflectance infrared Fourier transform spectroscopy. The combined approach of IGC and conventional techniques suggested that the changes in surface energy characteristics were associated with the formation of a disordered organic adlayer through SA chemisorption at various surface sites on crystalline facets with diverse coordination configurations. This highlights the potential of IGC as a powerful monitoring tool for investigating molecular coatings on ceramic nanopowders. It enables not only the quantification of average surface states but also provides insights into their distribution, which is not practically achievable through other surface characterization techniques.

Step by step progress to achieve an icephobic silicone‐epoxy hybrid coating: Tailoring matrix composition and additives

AbstractThis study details the fabrication of an icephobic coating for steel produced using a silicone–epoxy hybrid resin; the coating has good mechanical properties and weathering resistance for outdoor applications. Silicone–epoxy hybrid resins and amino‐functional silane‐curing agents were selected for investigation and applied to steel samples. Wettability, ice adhesion strength, and the mechanical and weathering resistance properties of the developed coatings were assessed using a drop‐shape analyzer, Fourier transform infrared, X‐ray photoelectron spectroscopy, as well as push‐off, tensile, and QUV tests. The possible correlation between ice adhesion strength and Young modulus was also investigated. The best‐performing matrix in terms of mechanical properties and weathering resistance had its surface energy characteristics altered—via two fluorinated silicone additives at various concentrations—to lower ice adhesion strength. For the steel substrates, the optimized additive‐altered surface showed a lower ice adhesion strength (decreasing from 362 to 94 kPa) with an adhesion reduction factor of 10.6. The fabricated coatings can serve as a protective layer for marine harbor infrastructures.

The Energy Characteristics of the Surface of Statistical Copolymers.

The results of systematic studies on the surface energy γ and its polar γP and dispersion γD components of statistical copolymers of styrene and butadiene, acrylonitrile and butadiene, and butyl acrylate and vinyl acetate, with regard to their thermal prehistory, are generalized. Along with copolymers, the surfaces of their composing homopolymers were examined. We obtained the energy characteristics of the adhesive surfaces of copolymers that contacted with air, high-energy aluminium Al (γ = 160 mJ/m2), and the low-energy substrate surface of polytetrafluoroethylene F4 (PTFE) (γ = 18 mJ/m2). The surfaces of copolymers in contact with air, aluminium, and PTFE were investigated for the first time. It was found that the surface energy of these copolymers tended to occupy an intermediate value between the surface energy of the homopolymers. The additive nature of the change in the surface energy of the copolymers with their composition, as previously established in the works of Wu, extends to the dispersive component of the free surface energy γD and the critical surface energy γcr, according to Zisman. It was shown that a significant influence on the adhesive activity of copolymers was exerted by the substrate surface upon which the adhesive was formed. Thus, for the butadiene-nitrile copolymer (BNC) samples formed in contact with a high-energy substrate, their surface energy growth was associated with a significant increase in the polar component of the surface energy γP from 2 mJ/m2 for the samples formed in contact with air, to an increase from 10 to 11 mJ/m2 for the samples formed in contact with Al. The reason why the interface influenced the change in the energy characteristics of the adhesives was the selective interaction of each macromolecule fragment with the active centres of the substrate surface. As a result, the composition of the boundary layer changed and it became enriched with one of the components. The structure of such layers is nonequilibrium. The thermal annealing of copolymers in the mode of a stepwise temperature increase led to a convergence in the values of γ, asymptotically tending to the value characteristic of the surface of the copolymers formed in air. The activation energies for the processes of the conformational rearrangements of the macromolecules in the surface layers of the copolymers were calculated. It was found that the conformational rearrangements of the macromolecules in the surface layers occurred as a result of the internal rotation of the functional groups that determined the polar component of the surface energy.

Wear of mold surfaces: Interfacial adhesion in precision glass molding

Micro-optical components, such as glass-based microlens arrays, have become essential in applications relying on advanced optical systems such as 3D displays, optical fiber coupling, and unmanned vehicles. Precision glass molding (PGM) has emerged as a promising method for fabricating optical components based on the formability of glasses beyond their glass transition temperature (Tg), while adhesion wear strength and mechanism of mold-glass interfaces remain major obstacles. This paper aims to explore the adhesion wear mechanisms between mold surfaces and optical glass D-FK95 in PGM. The applicability of WC molds with coatings of Ta–C, AlCrN, and AlTiN was investigated respectively considering their thermodynamic properties and surface energy characteristics. The study identified three adhesion wear mechanisms in the open-air atmosphere with WO3 oxidation on mold surfaces and four adhesion mechanisms featured by scattered distribution, island aggregation, dispersed flow, and planar coverage in an inert atmosphere. It was also found that when the temperature was close to Tg, the WC-glass adhesion force was negligible. The adhesion stress increased to 0.80 MPa with an increase in the applied temperature and pressure. With coating, however, the adhesion stress reduced significantly to 0.03 MPa. The study also concluded that when paired with the D-FK95 glass, the WC mold coated with Ta–C provides the best anti-adhesive performance in comparison to those with AlCrN and AlTiN coatings.

A renewable lignin-based thermoplastic adhesive for steel joining

Adhesive bonding of metals has become increasingly relevant in recent years due to the demand for reducing weight and improving performance in structural applications such as automobiles and aerospace. We developed renewable thermoplastic adhesives from technical organosolv lignin isolated from hardwood biomass and acrylonitrile butadiene co-polymer rubber (NBR) for joining steel substrates. NBR33, NBR41 and NBR51 with acrylonitrile molar ratios of 33, 41 and 51%, respectively, were blended with lignin to form two-phase thermoplastic adhesives, and their adhesion, viscoelastic and surface properties were measured. Lignin content in the compositions were varied, ranging from 40% to 80% (w/w), to alter toughness, stiffness, and surface energy characteristics of the material. Better interaction or reactivity between the lignin and NBR phases was observed with greater nitrile content in NBR, leading to greater modulus and stiffness of the adhesive. Simultaneously, increasing the proportion of lignin reduced toughness and improved stiffness, with the highest adhesive strength of 13.1 MPa measured in a 60% lignin loading ratio with NBR51. Surface energy measurements revealed that total surface energy (sum of polar and dispersive surface energy) raised with lignin loading, suggesting that both surface energy and matrix strength play a critical role in the adhesive properties of the synthesized materials. A finite element-based cohesive zone model (CZM) was developed and implemented to study the failure strength of the adhesively bonded joint. This study demonstrates the viability of lignin as a valuable building block for adhesives, not only due to its inherent chemical structure and rigidity, but also for its surface energy characteristics.

Antibiofouling Performance of a Metal‐Organic Gel Based on 2‐Amino‐5‐Mercapto‐1,3,4‐Thiadiazole and CuI

AbstractMetal–organic gels or metallogels (MOGs), which usually made up with metal ions and organic ligands, are promising in the area of medicine, environment, and biology. Herein, a new metal–organic gel containing Cu+ (Cu‐MOG‐5) is prepared at room temperature using 2‐amino‐5‐mercapto‐1,3,4‐thiadiazole (AMT) and CuI. Considering the excellent low surface energy characteristics of polydimethylsiloxane (PDMS), the as‐prepared Cu‐MOG‐5 is infused into porous PDMS to obtain Cu‐MOG‐5/PDMS coating, which combines the bactericidal properties of Cu+ containing hydrogels and the low surface energy of PDMS. The morphology of the Cu‐MOG‐5 and Cu‐MOG‐5/PDMS coating is investigated by FE‐SEM, and the structure of the new Cu‐MOG‐5 is verified by FT‐IR, 1H NMR, XPS, EDS, and elemental analysis. The antibiofouling properties are assessed using Escherichia coli (E. coli) and mussel. The results show that the newly prepared Cu‐MOG‐5/PDMS coating exhibits superior antibiofouling performance because of the synchronous action of hydrogel including Cu+ and PDMS.

Nonconventional 1,8-Diazafluoren-9-One Aggregates for Green Light Enhancement in Hybrid Biocompatible Media.

Organic aggregates currently play a prominent role, mainly for their unique optoelectronic properties in the aggregated state. Such properties can be related to the aggregates’ structure and the molecular packing mode. In the literature, we have well-established models of H and J aggregates defined based on the molecular exciton model. However, unconventional aggregates, the most unrecognized forms, have been generating interest among researchers recently. Within unconventional aggregation, aggregation-induced emission systems (AIE) are considered. In the present work, we discuss the effect of the forming of unconventional aggregation together with the change in dye concentration on the surface energy characteristics of the materials. All materials were prepared as hybrid biocompatible thin films where the matrix is TiO2 or TiO2/carbon nanowalls (CNWs) with the incorporated dye in the form of 1,8-diazafluoren-9-one (DFO). Using the time-resolved emission spectra and the determination of surface parameters from contact angle measurements, we indicated the correlation between the changes in such parameters and the concentration of DFO dye in two types of TiO2 and TiO2/CNW structures. To examine the propensity of DFO for aggregation, the internal energy of the dye was assessed in several aggregate structures using Quantum chemistry calculations. The results emphasize that DFO is an attractive structure in the design of new fluorophores due to its low molecular weight, the presence of a nitrogen atom that provides good coordination properties, and the ability to form hydrogen bonds. Our studies show that when using suitable matrices, i.e., rigid media, it forms the preferred forms of aggregates in the excited state, characterized by high emission efficiency in the band maximum of around 550 nm.

Mobile technology of thermal modification of wood

Wood as a structural material has a number of disadvantages, including a short service life, relatively low dimensional stability, significant volumetric deformations under the influence of moisture, pronounced anisotropy and water absorption. Thermomodification slightly improves physical and mechanical properties, but the problem of changing surface characteristics, in particular adhesion, arises. In order to determine the technological characteristics of thermally modified wood and to develop possible measures to improve the technology of applying protective coatings, the surface energy and compressive strength limit along the fibers were determined. A comprehensive approach is applied to analyze the state of the thermally modified wood surface through the study of surface energy characteristics based on the Fowkes method, which takes into account dispersion, hydrogen and dipole-dipole interactions at the solid-liquid interface. According to the marginal angle of wetting, it was found that the process of thermal modification wood helps to increase the resistance of its surface to wetting due to a decrease in polarity by 1.68 times with an increase in the duration of modification to 30 min. At the same time, the surface free energy for samples modified at 300 °C for 5 min. is 64.5 mJ/m2, during 30 min. – 24.1 mJ/m2. Regarding compressive strength, thermal modification reduces the strength limit by 1.46 times. At a temperature of 300 ºС and a time of 5 min. and 15 min. the indicator remains at the level of ordinary wood – 42 MPa. Treatment for 30 min. reduces the strength limit to 29 MPa, wood loses plasticity. The obtained results make it possible to effectively choose stable coatings for such wood for high-quality surface treatment with paint and varnish materials. Knowing the moment of time from which the reduction of the strength limit begins, conducting the process of thermal modification becomes more controlled and makes it possible to predict the characteristics of the future material

Superhydrophilic Modification of Polycarbonate Substrate Surface by Organic Plasma Polymerization Film.

Superhydrophilicity performs well in anti-fog and self-cleaning applications. In this study, polycarbonate substrate was used as the modification object because of the low surface energy characteristics of plastics. Procedures that employ plasma bombardment, such as etching and high surface free energy coating, are applied to improve the hydrophilicity. An organic amino silane that contains terminal amine group is introduced as the monomer to perform plasma polymerization to ensure that hydrophilic radicals can be efficiently deposited on substrates. Different levels of hydrophilicity can be reached by modulating the parameters of plasma bombardment and polymerization, such as plasma current, voltage of the ion source, and bombardment time. The surface of a substrate that is subjected to plasma bombarding at 150 V, 4 A for 5 min remained superhydrophilic for 17 days. After 40 min of Ar/O2 plasma bombardment, which resulted in a substrate surface roughness of 51.6 nm, the plasma polymerization of organic amino silane was performed by tuning the anode voltage and operating time of the ion source, and a water contact angle < 10° and durability up to 34 days can be obtained.

Investigation on the characteristics and effect of plant fibers on the properties of asphalt binders

In this paper, the effect of five different plant fibers on the performance of asphalt binder was evaluated. During the research, the microstructure, components and thermal stability of these fibers were studied by Scanning Electron Microscopy, Fourier Transform Infrared Spectrometer and thermogravimetric analysis. The surface energy characteristics of five plant fibers was investigate by a contact angle test. To estimate the performance of five plant fiber asphalt binders, the cone penetration test, temperature sweep test, multiple stress creep recovery test and bending beam rheometer test were carried out. Results showed that bagasse fiber, corn straw fiber and cotton straw fiber presented hollow structure and their surface textures were rougher than bamboo fiber and lignin fiber. The functional group compositions of five plant fibers showed high similarity and the main components of these fibers were celluloses, hemicelluloses and lignin. All these fibers had good thermostability at working temperature. Within five plant fibers, corn straw fiber possessed the highest amount of surface free energy, which led to the best adhesion with asphalt binder. After applying these plant fibers, the toughness and permanent deformation resistance of asphalt binders were improved. Whereas, the low-temperature properties of fiber modified asphalt binders degraded. Within five plant fibers, corn straw fiber can better improve the road performance of asphalt binder. However, corn straw fiber was more vulnerable to moisture damage, which had adverse impacts on the water damage resistance of asphalt binder.

Indexation of mixed mode adsorbents using low temperature nitrogen adsorption and Silica-C18 surface energy scale

Mixed-mode chromatography is becoming increasingly popular in pharmaceutical and biopharmaceutical applications due to its unique selectivity and retention of a variety of compounds. Mixed-mode chromatography is a chromatographic method in which solutes interact with stationary phase through more than one interaction mode or mechanism. It is because of these complex interactions, however, that it is difficult to predict chromatographic behavior of analytes on mixed-mode columns. Characterization of different mixed-mode columns on the basis of surface energy characteristics has not been explored. In this study, different ratios of porous silica (Axia Luna 5 µm Silica – Phenomenex), and C18 (Axia Luna 5 µm C18 – Phenomenex), single mode adsorbents were blended in various ratios and analyzed by Low Temperature Nitrogen Adsorption (LTNA). A variety of commercially available mixed mode columns were also unpacked and the materials were analyzed by LTNA. Adsorption isotherms, surface area, and BET constants were obtained for all the blended materials in various ratios and the mixed-mode materials. A linear relationship between the BET C-constant and the blend ratio of silica has been observed. The results from the commercial mixed mode packing material showed similar surface energy characteristics to single mode C18 materials. This data suggests that the BET C-constant maybe a viable parameter that can be used to characterize mixed-mode columns on the basis of surface energy. Utilizing this surface energy scale in conjunction with the study of retention behaviors on mixed-mode material could lead to improvements in the understanding of method development on mixed-mode columns, allow the comparison of commercialized mixed-mode columns, and even predict retention behavior of an analyte in mixed-mode columns.

Impact of Hydrodynamic and Interfacial Interactions on Scale Formation in a Capillary Microchannel.

This study proposes a model for the kinetics and hydrodynamics of gypsum scale deposition on surfaces of anhydrite, calcite, dolomite, and sandstone rocks while interacting with the brines of 3000 and 6000 mg/L [Ca2+] at 363 K and 1 atm. To do so, this study utilizes the surface energy characteristics of an interacting scale-brine-rock system as well as the geochemical interactions between brine-brine and brine-rock. The results showed that the deposition flux decreases steeply over time, followed by asymptotic propensity as time elapses. A higher degree of salinity in terms of [Ca2+] increases the deposition flux as much as 2.9-fold for the flowing velocity of 10-6 m/s and 2.4-fold for a velocity of 10-5 m/s. Moreover, higher flow velocity would lead to more deposition on sandstone followed by carbonate and anhydrite rocks: ∼2.6-fold for the salinity of 3000 mg/L and 2.2-fold for 6000 mg/L [Ca2+].