Component Of Surface Free Energy Research Articles

Moisture damage resistance of pyro-oil modified bitumen with hydrated lime using surface free energy approach

Moisture damage (MD) in bituminous mixtures occurs due to the loss of cohesion in the bitumen or adhesion between the binder and aggregates. The existence of moisture may influence the bonding between aggregates and bitumen, which may affect the moisture susceptibility of the bituminous mix. Therefore, there is a need to understand the bonding-debonding properties and the moisture susceptibility of binders and mixes, at the material selection stage. Surface free energy (SFE) method is one of the proven techniques to quantify the moisture susceptibility of bituminous mixtures, by using contact angle (CA) determination of the component materials of the mix. This study aimed to evaluate the effect of hydrated lime (HL) on the moisture susceptibility of bituminous mixtures, with control (VG30) bitumen and pyro-oil modified bitumen (POMB) having different percentages of pyro oil, using the SFE approach. Also, the study compared the SFE characteristics of VG30 and POMB with and without the optimum content of HL. POMB binders were prepared by the addition of high-density polyethylene (HDPE) pyro oil in percentages of 1, 3, and 5% in a control bitumen. HL was added as 20%, 25%, and 30% by weight of bitumen in VG30 and POMB bitumen. The aggregates used in the study were limestone, basalt, gravel, and their SFE components were directly considered from the literature. The sessile drop method was used to measure the CA of bitumen and, in turn, determine the various SFE parameters using Van Oss–Chaudhury–Good theory. The moisture susceptibility of mixtures with and without HL was evaluated and compared. From the results, the MD resistance of the bituminous mixtures with modified and unmodified bitumen was found to be increased after the optimum of HL, depending upon the type of aggregates used. Basalt has a 27.41%, 23.38%, and 10.48% greater energy ratio (ER) with POMB1/25, POMB3/25, and POMB5/30, respectively, than VG30/30, the highest ER in modified base bitumen. This indicates that HDPE pyro-oil treatment improves MD resistance for basalt. Whereas for limestone and gravel, VG30/30 gives a maximum value of ER as compared to any other combination of HL modified POMB. The ER values would assist highway agencies in selecting the most compatible binder–aggregate combinations.

Predict the surface free energy of Ti/Zr/V chemical conversion coating on nickel by machine learning approach: Trees vs. neurons

The surface properties of chemical conversion treated materials have received increasing attention and surface free energy (SFE) is an important indicator of it. In this study, an environment-friendly Ti/Zr/V chemical conversion coating was deposited on the nickel and Artificial Neural Network (ANN), Random Forest (RF), and Extra Trees (ET) models were applied to further investigate the relationship between the SFE and the compositions of the conversion bath. The accuracy of SFE prediction of three machine learning models was quantified, and the obtained results reveal that the correlation coefficients for the ANN, RF, and ET models are 0.958, 0.979, and 0.963 for the prediction of dispersion components and 0.964, 0.942 and 0.921 for the prediction of polar components, respectively, and the ANN model shows more outstanding performance in general. The errors in the prediction of the ANN model for the polar and dispersion components of SFE are 0.336 and 0.421, respectively, which are smaller than the extended uncertainties obtained from conventional experimental methods. The obtained machine learning models can accurately predict the variations of SFE for modest changes in the conversion bath components, thus linking the formation mechanism of coating with the variations of SFE.

Modeling and prediction of surface free energy of pavement materials based on a single probe liquid using artificial neural network

Surface free energy (SFE) is a vital material property employed for the assessment of various pavement performances such as asphalt-aggregate adhesion, moisture resistance, material compatibility, etc. However, the conventional models for estimating the SFE of materials require the contact angles (CA) of multiple probe liquids (PL) on the material's surface. In addition, the process requires further computational effort to arrive at the SFE components. In an attempt to offer an accurate and quicker alternative method of estimating the SFE of materials with lesser effort, this study has explored the use of artificial neural network (ANN) to predict the SFE of pavement materials. A simple but novel data structuring was employed to predict the SFE using inputs from just a single PL. Variables needed for the successful prediction of SFE components were identified and studied. Sensitivity analysis along with relative importance was used to rank the predicting variables. The Lifshitz-van der Waals (LW) component ANN-model showed the best accuracy (RMSE = 1.652 J/m2, R = 0.984). The base and acid components models showed relatively lower performances, (RMSE = 2.560 J/m2, R = 0.943) and (RMSE = 0.575 J/m2, R = 0.818) respectively. However, the SFE components estimated from the ANN-models yielded a total SFE with very good accuracy (RMSE = 2.049 J/m2, R = 0.982). Further insight into which variables such as substrate-type, CA test method, PL type, etc. facilitate model accuracy was provided.

Development of superior chitosan–EDTA microparticles as an adsorbent base for solidifying the self-emulsifying drug delivery systems

BackgroundThe present study focused on developing a superior adsorbent carrier (microparticles) to solidify the self-emulsifying drug delivery system. The two approaches, solvent evaporation and spray drying, were explored to synthesize the microparticles using chitosan (CH) and EDTA disodium. The 32 full factorial design was applied to optimize the microparticle process produced by both methods.ResultsThe various characterization evaluations of the microparticles revealed amide linkages between the CH and EDTA disodium, and XRD results showed that microparticles were amorphous. The SE-CHEM (C2) and SD-CHEM (Y1) optimized microparticles were free-flowing and had percentage yield (%), 96 ± 1.2 and 58 ± 1.1, zeta potential (mV), 9 ± 0.44 and 4 ± 0.13, and particle size (μm), 3 ± 0.57 and 2 ± 0.4, respectively. SEM images showed uneven surfaces with wide void spaces and flaky texture for optimized microparticles Y1 and C2, respectively. The SE-CHEM (C2) had an oil adsorption capacity (OAC %) of 46 ± 0.54 and 60 ± 0.77, and oil desorption capacity (ODC %), 38 ± 0.65 and 56 ± 0.86, for Labrafac and Cremophor RH 40, respectively. The SD-CHEM (Y1) had an oil adsorption capacity (OAC %) of 59 ± 0.71 and 68 ± 0.39, and oil desorption capacity (ODC %), 54 ± 0.11 and 65 ± 0.74, for Labrafac and Cremophor RH 40, respectively. In the surface free energy components analysis, the SE-CHEM (C2) had an enhanced dispersive component [γLW (mJ/m2)] of 32 ± 0.68 and 37 ± 0.47 for Labrafac and Cremophor RH 40, respectively. The SD-CHEM (Y1) had an enhanced dispersive component [γLW (mJ/m2)] of 48 ± 0.7 and 52 ± 0.41 for Labrafac and Cremophor RH 40, respectively. The SE-CHEM (C2) had enhanced dynamic advancing contact angles [θa (°)] of 75 ± 0.19 and 78 ± 0.75 for Labrafac and Cremophor RH 40, respectively. The SD-CHEM (Y1) had enhanced dynamic advancing contact angles [θa (°)] of 74 ± 0.6 and 80 ± 0.21 for Labrafac and Cremophor RH 40, respectively.ConclusionAll the findings indicate that the microparticles have superior characteristics to serve as the adsorbent base for solid self-emulsifying drug delivery systems.

Preparation of bioactive film based on chitosan and essential oils mixture for enhanced preservation of food products

Recently, the concept of biodegradable and bioactive packaging and surface coating has become a trend. In this work, the bioactive films of chitosan were elaborated following the casting method. Contrary to the films containing the Cinnamomum zeylanicum Blume, Thymus satureioides Cosson, and Syzygium aromaticum essential oils (EOs) mixtures, the control film was thin, colorless, and showed high moisture content, swelling degree, and elongation at break. Concerning the physicochemical parameters, the incorporation of the EOs mixtures minimized the hydrophobicity of the material (θw < 65°) and modified randomly its surface free energy components (γ−; γ+; γLW). The theoretical prediction of Aspergillus sp. and Rhizopus sp. adherence to the chitosan-based films was relatively correlated to the experimental results (r = −0.601). The latter showed that 6.80 % and 19.02 % of the control film surface was covered by Aspergillus sp. and Rhizopus sp. spores, respectively. In contrast, no fungal adherence was noticed in the case of the film incorporating the triple EOs mixture. These promising results revealed that chitosan film containing C. zeylanicum, T. satureioides, and S. aromaticum EOs mixtures could be utilized as a surface coating or bioactive packaging in the food industry.

Estimation of the Surface Free Energy Components for Solid Surfaces: A Machine Learning Approach

Estimation of the Surface Free Energy Components for Solid Surfaces: A Machine Learning Approach

Heterogeneities in the Cohesion of the Deposits of the 2021 Tajogaite Eruption of La Palma (Canary Islands, Spain)

The present study analyzes the electrical and thermodynamic properties of the volcanic ash deposits from the recent eruption that started on 19 September 2021 in the Cumbre Vieja area on the island of La Palma. This work compares the analysis of the zeta potential and the surface free energy components of representative samples of unaltered tephra deposits with samples affected by the fumarolic activity near the emission zone, where sulfurous vapors were present. The results show that fumarolic activity modifies both the zeta potential and the surface free energy components of volcanic ash, decreasing its surface electrical charge and conferring less hydrophilicity on the deposit. Based on this, the interaction energies between ash particles in an aqueous medium have been calculated, in order to analyze the cohesion of the deposit and, where appropriate, its rheological properties, ending with the analysis of the effect produced by different chemical species on the surface charge and free energy of the ashes, and their influence on the cohesion of the deposit. The results confirm an attractive interaction energy between the ash particles and therefore greater stability to the deposit affected by fumarolic activity.

Hybrid green bionanocomposites based on chitosan/starch/gelatin and metallic nanoparticles for biological applications

Multicomponent composites based on natural biopolymers: chitosan, starch and gelatin in two different ratios (0.5:1:1 and 1:1:1) were in situ crosslinked by intermolecular interactions and used as matrices for zinc oxide and magnetite fillers. The bionanocomposite films have been evaluated by spectral and microscopy methods: Fourier-Transform Infrared spectrometry (FT-IR), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) confirming the electrostatic and hydrogen bonding interactions between the components of the polymeric matrices and the inorganic fillers and the crosslinking process. AFM and SEM images showed a compact, non-porous and homogenous morphology of the hybrid films, proving a good miscibility of the blends. At lower concentrations of embedded filler, the composites were less hardened and more ductile due to the interaction with the polymeric matrix. Increased amounts of inorganic NPs led to the reduced mechanical properties of the prepared materials and increased thermal stability. The bionanocomposites revealed a similar behavior of the dielectric constant with frequency and increased values at higher temperatures. The wettability of the films' surface and the values of the water sorption capacity revealed a slight hydrophilicity of the bionanocomposites as compared with the initial matrices. The biocompatibility, evaluated by means of the surface free energy components and the interfacial tension with blood, and the hemolysis analysis demonstrated that the bionanocomposites possess a low risk of thrombosis, being promising materials for in vivo biomedical applications.

The investigation of surface free energy components and moisture sensitivity damage of asphalt mixes modified with carbon black using the sessile drop method

Asphalt pavement is vulnerable to moisture damage when water infiltrates the asphalt-aggregate interface and weakens their bond. To prevent this problem, researchers have explored the use of additives to increase resistance against moisture damage. The moisture sensitivity of asphalt mixtures can be assessed by measuring their basic properties related to the mechanism of moisture damage. One effective approach to this is using the surface free energy method, which calculates bond energies between different materials’ surfaces and identifies the most appropriate combination of asphalt and aggregate. High cohesion or adhesion bonding is crucial for the proper performance of asphalt mixtures, such as moisture damage resistance. This study aimed to investigate the effect of carbon black additive on moisture damage resistance using surface free energy methods, comparing results with the Tensile Strength Ratio (TSR) test. Modified asphalts containing 4, 8, 12, and 16% carbon black were tested, with natural base asphalt as a control sample. The study used surface free energy theory to determine moisture sensitivity parameters of asphalt mixtures by obtaining surface free energy components of the raw materials and testing the ratio of tensile strength. Results showed that adding 8% carbon black to the asphalt mixture improved moisture sensitivity, and increasing additive content up to 16% reduced it but still provided better results than samples made with pure asphalt. The study concluded that the surface free energy method can determine the suitable combination of asphalt and aggregate materials for resistance against moisture damage.

Statistical evaluation of the changes in cellulose properties caused by the stepwise solvent exchange and esterification

The objective of the research was to empirically confirm the changes in cellulose reactivity caused by the pre-treatment with solvents of different polarity. Therefore, 5 solvents varying in their polar component of surface tension from 0 to 4.6 mN/m were chosen. Their impact on the biopolymer properties was carefully analysed concerning chemical structure, crystallinity and surface characteristics. It was revealed that the length of 6OH⋯O3′ intermolecular H-bonds increased upon each solvent-exchange from (0.2748 ± 0.0001) nm to approx. 0.2760 nm for non-polar solvents, hence, potentially affecting cellulose structure and availability of active centres capable of reaction. As a consequence of structural variations, dioxane- and toluene-exchanged cellulose exhibited, respectively, the lowest (around 0.6 mJ/m2) and the highest (approx. 3.1 mJ/m2) polar component of surface free energy. Therefore, these samples were esterified. Further investigation successfully confirmed expected differences. Toluene-exchanged sample exhibited degree of substitution oscillating around 20%, while dioxane-exchanged specimen – approx. 7%.

Adhesion Characteristics of Graphene-Modified Asphalt Using Surface-Free Energy Method

Graphene is an auspicious nanomodified material for asphalt pavements. This study aims to evaluate the effect of graphene composites (GCs) on the adhesion characteristics of asphalt based on surface-free energy (SFE) theory. The surface-free energy of graphene-modified asphalt was measured by the sessile drop method. The work of adhesion and stripping between asphalts and two kinds of aggregates were calculated through using their surface-free energy components. The macroadhesion property between asphalts and aggregates was obtained by the improved boiling method. Immersion Marshall test and freeze–thaw splitting test were conducted to verify the effectiveness of surface-free energy indexes. The results demonstrated that GC significantly increased total surface-free energy and dispersion components of asphalt but reduced the polarity components. The adhesion work between asphalt and both aggregates increased after modification, whereas the stripping work decreased after modification. GC can substantially improve the adhesion and resistance to moisture damage at the asphalt–aggregate interface, and the effect on asphalt-limestone is more obvious. There are strong correlations between macro evaluation indicators and surface-free energy calculated indexes, where the macro indicators are more strongly correlated with stripping work. Limestone is generally better at resisting moisture damage than granite. GC remarkably improved the water stability of the mixture, which further indicates that energy indexes are a good method to quantize the moisture damage resistance of hot mix asphalt (HMA). The high dosage of graphene-modified asphalt is potentially applicable to porous asphalt concrete (PAC) pavement with extra-large voids.

Optimizing the Neural Network Architecture for Automation of the Tailored UV Post-Treatment of Photopolymer Printing Plates

In this work, three types of photopolymer printing plates for packaging printing were subjected to varied UV (ultraviolet radiation) post-treatments, and their surface free energy (SFE) components were calculated. SFE of the photopolymer printing plate is crucial in the process of transferring the ink from the printing plate to the substrate. Calculated polar and dispersive SFE components were used to build and optimize artificial neural networks for the prediction of the surface properties of different photopolymer materials after the performed UVA and UVC post-treatments. In this way, the production of printing plates with tailored SFE components could be automated and optimized. Consequently, products with improved qualitative properties could be printed. Results of the research have shown that the choice of the neural network’s activation function is most significant for the minimization of the mean squared error (MSE), while the number of neurons and hidden layers in neural networks has less influence on MSE. The optimized neural networks applied for common photopolymer materials in this work have the potential to be applied for the automation of the printing plates’ post-treatment process and the production of printing plates with surface properties tailored to specific printing systems.

From Raw to Finished Cotton—Characterization by Interface Phenomena

Abstract Interface phenomena that occur at the solid–liquid interface, such as wettability, adsorption, and particle aggregation, depend on the kind and magnitude of the solid surface free energy and electrokinetic properties found in water solutions. These phenomena are crucial for textile dyeing, finishing, and care. They characterize the material surface and change with different material pretreatment and finishing. In this paper, electrokinetic potential, isoelectric point, point of zero charge, a specific amount of surface charge and surface free energy of raw, enzymatically scoured, bleached, and finished cotton fabrics were investigated. Electrokinetic potential was measured by a streaming potential method and a specific quantity of surface charge by the back-titration method. For determination of the solid surface free energy components, the thin-layer wicking and contact-angle methods were used. On the basis of these results, components of solid surface free energy were calculated and discussed.

Analytical study of silane-based and wax-based additives on the interfacial bonding characteristics between natural rubber modified binder and different aggregate types

The modification of asphalt binder with natural rubber latex (NR) significantly improves the rutting and fatigue resistance of asphalt mixtures. However, NR-modified binder is prone to low workability and wettability due to its high viscosity. Therefore, this research focuses on examining the influences of silane and wax-based additives on the wettability of natural rubber-modified binders and the binder-aggregates adhesion performances. In this study, experimental and analytical approaches were used. The contact angles of asphalt binder were measured using a goniometer through the sessile drop method with three solvents: deionised water, formamide, and glycerol. The C++ algorithm was adopted to compute the surface free energy (SFE) elements of the asphalt binder. Analytical methods were employed to analyse the results based on the Young-Dupre equation, followed by linear regression to establish a correlation between the compatibility ratio (CR) and the SFE components. The results inferred that modified asphalt binders with additives possessed improved moisture resistance, wherein dry work adhesion values were less than 210 ​mJ/m2 under granite interfaces, whereas the limestone interface exhibited higher dry adhesion values of 340 ​mJ/m2 and below. Similar performance results were observed under wet adhesion conditions; with granite wet adhesive values observed below 120 ​mJ/m2, while limestone wet adhesion values were ascertained below 180 ​mJ/m2 for all tested samples and conditions. According to the spread–ability coefficient results, the limestone interface has greater spread-ability than granite interfaces. Meanwhile, compatibility ratio values indicated better compatibility of 1.9 or higher for tested samples under granite interfaces, whereas compatibility values of 1.7 and below were observed under limestone interfaces. Among the SFE components studied for correlation with CR, the acidic SFE component demonstrated excellent correlations (with R2 values greater than 0.91) under all ageing conditions. An inclusion of micro-level additive enhanced binder adhesion properties, resulting in a more resilient asphalt pavement.

Application of inverse gas chromatography to bench scale flotation of sulphide ore

ABSTRACT Inverse gas chromatography (IGC) is receiving increasing attention due to its high precision and ease of application in determining various characteristics of a wide variety of materials of different shapes and morphologies. This study details an experimental investigation into the application of the IGC technique to the flotation of sulphide minerals. Rather than giving the surface energy, the trends associated with the various concentrates and tailings are described. Bench-scale flotation experiments of a nickel-copper sulphide ore were conducted in a Denver flotation cell. The IGC analyses were carried out on the timed concentrates, as well as on the final tailings, in order to evaluate the correlation between surface energetics and the flotation response of the ore particles. The results indicated that the floatability of the concentrates was directly related to the surface energy of the particles. Both dispersive and specific components of surface free energy increased by increasing the necessary time for the particles to be floated, which was consistent with the obtained values for the work of adhesion to water. However, the flotation response of the tailings was not consistent with the expectations from the surface energy value. The significance of the sample composition, particle size distribution, and their consequences in surface energy-flotation response relationship were also observed.

High variability of interaction energy between volcanic particles: implications for deposit stability

Landslides on the flanks of stratovolcanoes can significantly modify the structure of the volcano. Macroscopic factors that determine the stability of volcanic deposits are well understood, but the microscopic interactions between particles and their impact on deposit cohesion remain poorly understood. Deposit cohesion is related to the energy of interaction between particles, and its calculation depends on the surficial properties of the eruptive materials. The purpose of this study was to perform a preliminary comparative analysis of the surficial properties of volcanic materials from various tectonic settings, including electrical (zeta potential) and thermodynamic (surface free energy) components and to calculate the total interaction energy between particles under different environmental conditions. We analyzed samples of eruptive materials obtained from volcanic flows characteristic of six active volcanoes (El Hierro, Pico Do Fogo, Vulcano, Stromboli, Mt. Etna, and Deception Island). The results show that deposit cohesion varies among volcanoes and changes drastically with the pH of the medium. Among the volcanic systems investigated, El Hierro (pH = 3) has the most cohesive materials, while Mt. Etna (pH = 8) has the least cohesive materials. Our results suggest that microscopic electrical and thermodynamic properties play a role in the stability of volcanic deposits, and confirm the need for a greater research focus in this area.

The relationships between surface and electrical properties of CSA doped PANI films

Comprehensive surface free energy (SFE) analysis and surface-electrical property relationships of de-doped and camphorsulfonic acid (CSA) doped polyaniline (PANI) films were not handled systematically previously. In this work, changes of surface and electrical properties of CSA doped PANI films were evaluated simultaneously with respect to dopant concentration. For this purpose, PANI was synthesized and subjected to secondary doping process by using various amounts of CSA in m-cresol medium. Following this, detailed SFE analysis of both de-doped and CSA doped PANI films was performed by evaluating the wettability characteristics of these films through contact angle measurements. The Lifshitz-van der Waals (LW) and polar (acidic, basic) components of SFE were calculated by using acid-base (AB) and geometric mean (GM) approaches. The results suggest that while the polar components and total SFE tend to be ever increasing with CSA concentration, the conductivity reaches a maximum at 55 wt% CSA. Also, the rate of increase of the acidic component of SFE was limited when conductivity is increasing. However, when conductivity tends to decrease, such rate was found to be rapidly increasing. The underlying mechanism of this behavior was discussed along with FTIR, XRD, SEM, 3D profilometer, and contact angle hysteresis analysis.

Moisture damage susceptibility of a wood-based bio-binder for total replacement of asphalt binders

There is limited information on the characteristics and performance of paving mixtures made with 100% bio-binders. Moisture damage resistance of this type of mixture is a concern since the components of the bio-binder may have a higher affinity with water than asphalt binders. In this context, this paper presents a moisture damage susceptibility evaluation of wood-based bio-binder-aggregate interfaces in terms of energy parameters calculated from surface free energy components. The bio-binder was used as a total replacement for asphalt binders, and the responses were compared to a neat- and a highly modified-asphalt binder, considering different aggregate sources. Results suggest the bio-binder has similar moisture damage resistance to the neat asphalt binder and higher resistance than the highly modified asphalt binder, providing a first indication for the potential use of this bio-binder as 100% asphalt binder replacement. However, additional research is still required to validate these findings at the mixture level.

Aging of Polylactide Films Exposed to Plasma—Hydrophobic Recovery and Selected Application Properties

In this study, the effect of polylactide (PLA) material on the susceptibility to hydrophobic recovery due to storage was examined, the effectiveness of plasma activation of the film, defined as improving the hydrophilicity of the material, was studied, and the selected film properties that are important from an application point of view were investigated. The study was conducted on three films using oxygen and argon plasma. Contact angles of water, diiodomethane, and ethylene glycol were investigated, and the values of surface free energy (SFE) and its polar and dispersive components were determined immediately after activation, as well as after a specified storage time (after 1, 7, 14, 30, and 60 days). The effects of film activation on its roughness, weight loss, tensile strength, color changes, and gloss were also determined. Based on the results, it was concluded that the type of film influences the course of hydrophobic recovery. At the same time, the trend of changes depends on the type of gas used for activation, while the magnitude of changes depends on the film. Moreover, it was observed that the type of PLA film had a significant effect on the changes in the polar and dispersion components of SFE, as well as on roughness and mass loss due to plasma activation. Furthermore, these parameters also depended on the type of gas used for plasma activation.

Characterisation of the Surface Free Energy of the Recycled Cellulose Layer that Comprises the Middle Component of Corrugated Paperboards

The objective of this study was to determine the polar and dispersive surface free-energy (SFE) components of the central layer of corrugated paperboards, which are made of recycled fibres. The polar and dispersive components of, and the total, SFE (also known as interfacial energy) were calculated from the contact angles of water and diiodomethane liquids on recycled cellulose sheets. The total SFE of the middle component layers of two different grammages which comprised recycled fibres ranged from 47.9 mN/m to 51.05 mN/m. The contribution of the polar component to the total surface free energy of the two types of sheets ranged from 8.6 mN/m to 12.6 mN/m. This polar contribution was significantly lower than that of water. The contact angle method proved to be a consistent way to estimate the surface properties of industrially made recycled paper products.