Total Surface Energy Research Articles

Comparative study of plasma, laser, and flame induced activation of HDPE liner surfaces of type 4 hydrogen vessels

ABSTRACT In our study, we compare the surface modifications of coarse HDPE surface induced by atmospheric air plasma, CO2 laser, and flame treatments. An order of WCA decrease of air plasma>flame>CO2 laser methods was detected. The improvement in adhesion strength measured 5 days after the activations followed the same trend. FT-IR and EDS proved that different oxygen compounds were formed after treatments, resulting in increased polar component of the total surface energy. Flame activation showed a saturation character regarding the O-moiety. Hydrophobic recovery showed a linear behavior, with a larger decreasing slope for the polar component than the total surface energy. Plasma treatments induced higher recovery rate; however, restore was not complete here either. The effects of the different CO2 irradiation intensities were nonlinear; SEM and roughness measurements revealed surface ablation or structure formation on the different samples, while after plasma and flame treatment a hilly microtexture appeared. With different mechanisms and intensities, all the tested methods are suitable for increasing the adhesion strength on HDPE surfaces.

Estimating contact angle of pure and mixed liquids on smooth solid surfaces using dispersive-to-attractive surface energy ratio from PCP-SAFT model

This study introduces a novel methodology using the PCP-SAFT model and Young equation to estimate contact angles of pure and mixed liquids on solid surfaces. By considering the dispersion and non-dispersion contributions to the Helmholtz energy, our approach estimates the ratio of dispersion to total surface energy, that is crucial to predict contact angles. Comparing our results with literature data demonstrates high accuracy; the average absolute relative deviation (AARD) of 6.65% is achieved for estimating the ratio of dispersion surface tension to total surface tension of 13 liquids and 9.27% for estimating contact angle for 70 systems at room condition. Moreover, our model effectively captures the temperature and composition variations for binary mixtures on various surfaces, showing its applicability in understanding the wetting behavior. The PCP-SAFT model offers a promising tool for estimating the ratio of dispersion surface tension to total surface tension, required to estimate contact angle as an important measure of surface wetting.

Study of structural, surface energies, and tribomechanical properties of thermoplastics irradiated by electron beam

This study investigates the effects of electron irradiation on the structural, surface energy, and tribomechanical properties of two key thermoplastics: polyetheretherketone (PEEK) and polytetrafluoroethylene (PTFE). The experimental methods included electron beam irradiation using the ILU-10 pulsed linear accelerator, Fourier transform infrared spectroscopy (FT-IR), x-ray diffraction (XRD), microhardness testing, surface roughness assessment, tribology tests, and contact angle measurements.The FT-IR analysis revealed significant chemical changes on the surfaces of the polymers, including oxidation processes and the breaking of molecular bonds. XRD analysis showed an increase in the crystallinity of PTFE after irradiation, while the structure of PEEK remained stable. Microhardness testing indicated a notable increase in hardness for both polymers, particularly for PTFE, suggesting cross-linking of molecular chains. Surface roughness measurements demonstrated a decrease in roughness for both irradiated polymers. Tribology tests revealed that electron irradiation increased the coefficient of friction for PTFE and PEEK under various loads, which can be attributed to the alterations in their surface properties. Contact angle measurements indicated improved wettability of the irradiated surfaces, especially for PEEK, due to the formation of new functional groups. The total surface energy increased for both polymers post-irradiation, as determined using the Owens-Wendt-Rabel-Kaeble method. Electron irradiation leads to significant modifications in the surface and bulk properties of PEEK and PTFE, enhancing their tribomechanical and adhesive properties. These changes open new opportunities for the application of these materials in various engineering fields where specific performance characteristics are required.

Diameter-dependent phase selectivity in 1D-confined tungsten phosphides

Topological materials confined in 1D can transform computing technologies, such as 1D topological semimetals for nanoscale interconnects and 1D topological superconductors for fault-tolerant quantum computing. As such, understanding crystallization of 1D-confined topological materials is critical. Here, we demonstrate 1D template-assisted nanowire synthesis where we observe diameter-dependent phase selectivity for tungsten phosphides. A phase bifurcation occurs to produce tungsten monophosphide and tungsten diphosphide at the cross-over nanowire diameter regime of 35–70 nm. Four-dimensional scanning transmission electron microscopy is used to identify the two phases and to map crystallographic orientations of grains at a few nm resolution. The 1D-confined phase selectivity is attributed to the minimization of the total surface energy, which depends on the nanowire diameter and chemical potentials of precursors. Theoretical calculations are carried out to construct the diameter-dependent phase diagram, which agrees with experimental observations. Our findings suggest a crystallization route to stabilize topological materials confined in 1D.

Tilted-Plane Structure of the Energy of Finite Quantum Systems.

The piecewise linearity condition on the total energy with respect to the total magnetization of finite quantum systems is derived using the infinite-separation-limit technique. This generalizes the well-known constancy condition, related to static correlation error, in approximate density functional theory. The magnetic analog of Koopmans' theorem in density functional theory is also derived. Moving to fractional electron count, the tilted-plane condition is derived, lifting certain assumptions in previous works. This generalization of the flat-plane condition characterizes the total energy surface of a finite system for all values of electron count N and magnetization M. This result is used in combination with tabulated spectroscopic data to show the flat-plane structure of the oxygen atom, among others. We find that derivative discontinuities with respect to electron count sometimes occur at noninteger values. A diverse set of tilted-plane structures is shown to occur in d-orbital subspaces, depending on chemical coordination. General occupancy-based total-energy expressions are demonstrated thereby to be necessarily dependent on the symmetry-imposed degeneracies.

Evaluation of Polyvinyl Alcohol as Binder during Continuous Twin Screw Wet Granulation.

Binder selection is a crucial step in continuous twin-screw wet granulation (TSWG), as the material experiences a much shorter residence time (2-40 s) in the granulator barrel compared to batch-wise granulation processes. Polyvinyl alcohol (PVA) 4-88 was identified as an effective binder during TSWG, but the potential of other PVA grades-differing in polymerization and hydrolysis degree-has not yet been studied. Therefore, the aim of the current study was to evaluate the potential of different PVA grades as a binder during TSWG. The breakage and drying behavior during the fluidized bed drying of drug-loaded granules containing the PVA grades was also studied. Three PVA grades (4-88, 18-88, and 40-88) were characterized and their attributes were compared to previously investigated binders by Vandevivere et al. through principal component analysis. Three binder clusters could be distinguished according to their attributes, whereby each cluster contained a PVA grade and a previously investigated binder. PVA 4-88 was the most effective binder of the PVA grades for both a good water-soluble and water-insoluble formulation. This could be attributed to its high total surface energy, low viscosity, good wettability of hydrophilic and hydrophobic surfaces, and good wettability by water of the binder. Compared to the previously investigated binders, all PVA grades were more effective in the water-insoluble formulation, as they yielded strong granules (friability below 30%) at lower L/S-ratios. This was linked to the high dispersive surface energy of the high-energy sites on the surface of PVA grades and their low surface tension. During fluidized bed drying, PVA grades proved suitable binders, as the acetaminophen (APAP) granules were dried within a short time due to the low L/S-ratio, at which high-quality granules could be produced. In addition, no attrition occurred, and strong tablets were obtained. Based on this study, PVA could be the preferred binder during twin screw granulation due to its high binder effectiveness at a low L/S-ratio, allowing efficient downstream processing. However, process robustness must be controlled by the included excipients, as PVA grades are operating in a narrow L/S-ratio range.

A structure-preserving finite element method for the multi-phase Mullins–Sekerka problem with triple junctions

We consider a sharp interface formulation for the multi-phase Mullins–Sekerka flow. The flow is characterized by a network of curves evolving such that the total surface energy of the curves is reduced, while the areas of the enclosed phases are conserved. Making use of a variational formulation, we introduce a fully discrete finite element method. Our discretization features a parametric approximation of the moving interfaces that is independent of the discretization used for the equations in the bulk. The scheme can be shown to be unconditionally stable and to satisfy an exact volume conservation property. Moreover, an inherent tangential velocity for the vertices on the discrete curves leads to asymptotically equidistributed vertices, meaning no remeshing is necessary in practice. Several numerical examples, including a convergence experiment for the three-phase Mullins–Sekerka flow, demonstrate the capabilities of the introduced method.

Multiscale off-fault brecciation records coseismic energy budget of principal fault zone

Breccia and pulverized rock are typical textures in off-fault damage adjacent to a main seismogenic zone. Previously, by estimating the energy required to advance the rupture in this zone using particle size distribution at sub-millimeter/micrometer scales, we could constrain the energy budget during coseismic events. However, whether microscopic estimation is sufficient to capture surface energy fragmentation during an earthquake and the effect of measurement scale variation on calculation of co-seismic energy partitioning remained unclear. Here, we investigated the mechanism of coseismic off-fault damage based on field and microstructural observations of a well-exposed breccia body in Ichinokawa, Japan. We used in situ clast measurements coupled with thin-section analysis of breccia clasts to estimate the energy budget of the damage zone adjacent to the principal slip zone of the Median Tectonic Line (MTL). The total surface energy density and corresponding surface energy per unit fault for a width of ~ 500 m of the dynamical damage zone were estimated. The moment magnitude estimated based on surface energy was 5.8–8.3 Mw. In Ichinokawa, off-fault fragmentation is initiated by coseismic activity and is followed by fluid activity. Under dynamic fragmentation conditions, the scale is important to calculate the surface energy.

The Effect of Temperature on the London Dispersive and Lewis Acid-Base Surface Energies of Polymethyl Methacrylate Adsorbed on Silica by Inverse Gas Chromatography

Inverse gas chromatography at infinite dilution was used to determine the surface thermodynamic properties of silica particles and PMMA adsorbed on silica, and more particularly, to quantify the London dispersive energy γsd, the Lewis acid γs+, and base γs− polar surface energies of PMMA/silica composites as a function of the temperature and the recovery fraction θ of PMMA. The polar acid-base surface energy γsAB and the total surface energy of the different composites were then deduced as a function of the temperature. In this paper, the Hamieh thermal model was used to quantify the surface thermodynamic energy of polymethyl methacrylate (PMMA) adsorbed on silica particles at different recovery fractions. A comparison of the new results was carried out with those obtained by applying other molecular models of the surface areas of organic molecules adsorbed on the different solid substrates. An important deviation of these molecular models from the thermal model was proved. The determination of γsd, γs+, γs−, and γsAB of PMMA in both the bulk and adsorbed phases showed an important non-linearity variation of these surface parameters as a function of the temperature. The presence of maxima in the curves of γsd(T) highlighted the second-order transition temperatures in PMMA showing beta-relaxation, glass transition, and liquid–liquid temperatures. These three transition temperatures depended on the adsorption rate of PMMA on silica. The proposed method gave a new relation between the recovery fraction of PMMA and its London dispersive energy, showing an important effect of the temperature on the surface energy parameters of the adsorption of PMMA on silica. A universal equation relating γsd(T,θ) of the systems PMMA/silica to the recovery fraction and the temperature was proposed.

Effect of water and ionic liquid vapors on the structural properties of gold nanoclusters formed during inert-gas condensation process using molecular dynamics simulations

In this research, process of Au nanocluster formation has been investigated using the inert-gas condensation process in different environments with different concentrations of Ar gas, water vapor, and IL molecules. We have calculated the total energy, relative stability, surface energy, and radial distribution function (RDF) of the different produced clusters at different simulation times. Our results showed that the number of formed clusters increases, whereas their size decreases by increasing the water and IL concentrations in the environment. The water and IL molecules adsorb on the nanoclusters surfaces and hinder the coalescence of the smaller clusters to form bigger clusters. The percentage of the fcc and hcp atoms also decreases by increasing the water and IL concentrations. The produced clusters also become more non-spherical by increasing the IL and water vapor in the environment (with exception of the pure vapors).

Enhancing CFRP laminates with plasma jet arrays: A study of interlaminar mechanical properties

AbstractThis study delves into the efficacy of plasma jet array treatment in bolstering the interlaminar toughness of Carbon Fiber Reinforced Polymer (CFRP) prepregs, a crucial parameter for their deployment in high‐performance domains. Employing high‐frequency pulsed microsecond plasma jet arrays for surface modification, this research not only demonstrated a 19.49% upsurge in peak load capacity but also a remarkable 29.94% enhancement in Mode I interlaminar fracture toughness, as evident from Double Cantilever Beam (DCB) tests. Furthermore, the surface wettability improvements were underscored by a substantial decrease in water contact angle from 108.33° to 31.45° and a total surface energy augmentation from 12.20 to 64.16 mN/m, post a 1‐min plasma treatment. X‐ray Photoelectron Spectroscopy (XPS) results indicated an appreciable rise in oxygen functionalities, suggesting enhanced resin‐fiber bonding. Additionally, Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) analyses revealed notable decreases in surface roughness and microscale defects, contributing to smoother surfaces conducive to better adhesive bonding and reduced manufacturing defects. These multifaceted improvements, stemming from alterations in surface chemistry and topography, underpin the significant potential of plasma treatment in advancing CFRP laminate applications requiring superior durability and mechanical resilience.Highlights A plasma jet arrays method to enhance CFRP's interlaminar properties was studied. The influence mechanism of plasma modification was revealed in detail. The interlayer toughening mechanism of CFRP after plasma modification is proposed.

Enhancing the bond strength between glass fibre reinforced polyamide 6 and aluminium through μPlasma surface modification

Thermoplastic polymers generally exhibit relatively low surface energies and this often results in limited adhesion when bonded to other materials. Plasma surface modification offers the potential to functionalise the polymer surfaces, and thereby enhance the bond strength between dissimilar materials. In this study, glass fibre reinforced polyamide 6 (GFPA6) was modified using a novel μPlasma surface treatment technique and the effectiveness of the adhesive bond with aluminium was evaluated. The treated GFPA6 surfaces were characterised using atomic force microscopy (AFM), Raman spectroscopy, contact angle measurements, surface free energy calculations and wetting envelope analysis. The results show that there was a near exponential growth in root mean square roughness with increasing treatment scans. A significant increase in carbonyl and amide functionality on the polymer surface was observed using Raman spectroscopy. The total surface energy was found to increase from 42.2 mN/m to 67.6 mN/m following a single treatment scan. Significant increases in the tensile shear strength were observed up to 10 treatment scans, going from 1 kN to 2.3 kN, but no further increase was observed with additional treatment scans. These observations, coupled with the atmospheric nature of the technique, points to great potential as a rapid, on-line, and effective, polymer surface treatment technique.

Hygroscopicity of nitrocellulose with different nitrogen content

AbstractResearch on the hygroscopic behavior of NC is essential because it affects the mechanical properties, combustion properties, and safe storage of NC‐based products. In this study, Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), and scanning electron microscopy (SEM) are used to characterize the chemical structure, crystal structure, and microscopic morphology of NC, respectively. The moisture adsorption isotherms of NC fibers with different nitrogen content are determined by dynamic vapor sorption (DVS) and fitted with Hailwood‐Horrobin (H−H) and Guggenheim‐Anderson‐de Boer (GAB) models. The specific surface area and surface energy of NC are also measured by inverse gas chromatography (IGC). The results show that as the nitrogen content of NC increases, the intensity of the −OH characteristic absorption peak is weakened, the crystallinity does not change much, the number of cracks and pores on the NC fiber surface increases, and the equilibrium moisture content (EMC) of the NC decreases in general. In addition, the fitting results based on the H−H and GAB models show that, under low humidity conditions, the EMC value of NC is determined by the adsorbed water content of the monolayer, which is mainly related to the −OH content in NC. However, with the increase of humidity, the EMC value of NC is gradually determined by the multilayer adsorbed water content, which is influenced by both the nitrogen content and the fiber cleavage structure. Meanwhile, the IGC results show that the surface energy of the NC consists mainly of the dispersive surface energy (values >46 mJ m−2), with the specific surface energy contributing approximately 25 mJ m−2. The total surface energy of NC and the bonding strength between NC molecules and water molecules decrease with increasing nitrogen content.

Nanotexture and crystal phase regulation for synergistic enhancement in re-endothelialization on medical pure titanium surface

Re-endothelialization has been recognized as a promising strategy to address the tissue hyperplasia and subsequent restenosis which are major complications associated with vascular implant/interventional titanium devices. However, the uncontrollable over-proliferation of smooth muscle cells (SMCs) limits the clinical application of numerous modified strategies. Herein, a novel modified strategy involving with a two-step anodic oxidation and annealing treatment was proposed to achieve rapid re-endothelialization function regulated by regular honeycomb nanotexture and specific anatase phase on the titanium surface. Theoretical calculation revealed that the presence of nanotexture reduced the polar component of surface energy, while the generation of anatase significantly enhanced the polar component and total surface energy. Meanwhile, the modified surface with regular nanotexture and anatase phase produced positive effect on the expression of CD31, VE-Cadherin and down-regulated α-SMA proteins expression, indicating excellent capacity of pro-endothelial regeneration and inhibition of SMCs proliferation and migration. One-month in vivo implantation in rabbit carotid arteries further confirmed that modified tube implant surface effectively accelerated confluent endothelial monolayer formation and promoted native-like endothelium tissue regeneration. By contrast, original titanium tube implant induced a disorganized tissue proliferation in the lumen with a high risk of restenosis. Collectively, this study opens us an alternative route to achieve the function that selectively promotes endothelial cells (ECs) growth and suppresses SMCs on the medical titanium surface, which has a great potential in facilitating re-endothelialization on the surface of blood-contacting titanium implant.

Specific Heat Capacity of Solar Salt-Based Nanofluids: Molecular Dynamics Simulation and Experiment.

In this study, a nanofluid composed of molten solar salt (MSS) and 1.0% SiO2 nanoparticles by mass was created and analyzed using differential scanning calorimetry (DSC) to determine its specific heat capacity (SHC). The SHC of the nanofluid was found to be significantly higher than that of pure MSS. The average increase in SHC of the nanofluid with 1.0% SiO2 nanoparticles (NPs) loading was found to be 15.65% compared with pure MSS. The formation of nanostructures after doping with NPs may increase the SHC of molten salt (MS) nanofluids, according to certain published research that included experimental confirmation. Nevertheless, no thorough theoretical or computational studies have been conducted to verify the experimental findings related to MSS nanofluid. Molecular dynamics (MD) simulations were conducted in various simulation boxes for different cases to verify the experimental findings and investigate the mechanism behind the enhancement of SHC caused by the addition of SiO2 NPs in eutectic MSS. The simulations used pure MSS and mixtures containing NaNO3 nanostructures bonded with SiO2 NPs. The highest SHC increase of 25.03% was observed when the simulation box contained 13.71% NaNO3 nanostructures by weight. The incorporation of NaNO3 nanostructures increased the surface area and total surface energy, leading to a positive effect on the SHC of the MSS nanofluid. However, the decrease in the base molten salt's SHC had a slight negative impact on the overall SHC of the MS nanofluid.

Optimization of Rough Self-Propelled Rotary Turning Parameters in terms of Total Energy Consumption and Surface Roughness

Optimization of Rough Self-Propelled Rotary Turning Parameters in terms of Total Energy Consumption and Surface Roughness

The extracellular polysaccharide determine the physico-chemical surface properties of Microcystis.

Microcystis possesses the capacity to form colonies and blooms in lakes and reservoirs worldwide, causing significant ecological challenges in aquatic ecosystems. However, little is known about the determining factors of physico-chemical surface properties that govern the competitive advantage of Microcystis. Here, The physico-chemical surface properties of Microcystis wesenbergii and Microcystis aeruginosa, including specific surface area (SSA), hydrophobicity, zeta potential, and functional groups were investigated. Additionally, the extracellular polysaccharide (EPS) were analyzed. Laboratory-cultured Microcystis exhibited hydrophilic, a negative zeta potential and negatively charged. Furthermore, no significant relationship was shown between these properties and the cultivation stage. Microcystis wesenbergii exhibited low free energy of cohesion, high surface free energy, high growth rate, and high EPS content during the logarithmic phase. On the other hand, M. aeruginosa displayed lower free energy of cohesion, high surface free energy, high EPS content, and high growth rate during the stationary phase. These characteristics contribute to their respective competitive advantage. Furthermore, the relationship between EPS and surface properties was investigated. The polysaccharide component of EPS primarily influenced the SSA and total surface energy of Microcystis. Likewise, the protein component of EPS influenced hydrophobicity and surface tension. The polysaccharide composition, including glucuronic acid, xylose, and fructose, mainly influenced surface properties. Additionally, hydrophilic groups such as O-H and P-O-P played a crucial role in determining hydrophobicity in Microcystis. This study elucidates that EPS influenced the SSA, hydrophobicity, and surface free energy of Microcystis cells, which in turn impact the formation of Microcystis blooms and the collection.

Ionenes as Potential Phase Change Materials with Self-Healing Behavior.

Ionenes are poly(ionic liquids) (PILs) comprising a polymer backbone with ionic groups along the structure. Ionenes as solid-solid phase change materials are a recent research field, and some studies have demonstrated their potential in thermal dissipation into electronic devices. Eight ionenes obtained through Menshutkin reactions were synthesized and characterized. The analysis of the thermal tests allowed understanding of how the thermal properties of the polymers depend on the aliphatic nature of the dihalogenated monomer and the carbon chain length. The TGA studies concluded that the ionenes were thermally stable with T10% above 420 °C. The DSC tests showed that the prepared ionenes presented solid-solid transitions, and no melting temperature was appreciated, which rules out the possibility of solid-liquid transitions. All ionenes were soluble in common polar aprotic solvents. The hydrophilicity of the synthesized ionenes was studied by the contact angle method, and their total surface energy was calculated. Self-healing behavior was preliminarily explored using a selected sample. Our studies show that the prepared ionenes exhibit properties that make them potential candidates for applications as solid-solid phase change materials.

Recycled carbon fiber potential for reuse in carbon fiber/PA6 composite parts

Pyrolysis reclaiming is the most promising process to treat high volumes of composite waste with an advantageous carbon footprint. This paper aims to compare pyrolysis reclaimed carbon fibers (RCF) to virgin sized fibers (VF) and de-sized fibers (VFT) in their capability to bond to a polyamide 6 matrix. Micromechanical tensile testing of single fiber samples of the three fiber types was conducted. A minor reduction in tensile strength and an unchanged elastic modulus of the RCF compared to VF was observed. Scanning electron microscopy and atomic force microscopy scans were used to evaluate the morphology of the fibers. To evaluate the surface energy of the fibers, tensiometric testing was conducted. RCF showed a better adhesion capability compared to VFT through higher total surface energy. Moreover, X-ray spectrophotometry scans highlighted a higher proportion of functional groups at the RCF surface compared to VFT. Finally, pull-out tests underlined a decrease of the interfacial shear strength of RCF and VFT by 35% compared to VF. Overall, this study’s results further the understanding of the impact of the pyrolysis reclaiming process on RCF mechanical and adhesion properties.

The predictive factors that total laser energy consumed during retrograde intrarenal surgery (RIRS): stone area and density

Holmium: YAG (Ho: YAG) laser lithotripsy with flexible ureterorenoscopy can be used with high stone-free and low complication rates for renal stones. This study aimed to determine the factors affecting the total laser energy in cases with provided stone-free status after a single session of retrograde intrarenal surgery (RIRS). Data of 222 patients who underwent RIRS between October 2017 and March 2020 were evaluated retrospectively. After exclusion criteria, the study was carried out with 184 stone-free cases. All cases were performed without using a ureteral access sheath (UAS), and dusting was preferred as the lithotripsy method. The effects of age, gender, body mass index (BMI), previous RIRS history, previous shock wave lithotripsy (SWL) history, stone localization, number of stones, stone surface area, and stone density on total laser energy were analyzed. There was no significant correlation between total laser energy with gender, BMI, previous RIRS history, previous SWL history, stone localization, and the number of stones (p:0.347, p:0.482, p:0.119, p:0.167, p:0.907, p:0.933 respectively). There was a significant correlation between age and total laser energy (p = 0.032), but it was not observed when the effect of the stone surface area was removed (p = 0.354). There were significant correlations between total laser energy and stone surface area, stone density, and total laser time (p<0.001, p<0.001, and p <0.001, respectively). Stone area and stone density affect the total energy consumed during laser lithotripsy. Urologists should consider the stone area, stone density, and the power of the laser device to determine which surgical technic to prefer.