Surface Free Energy Values Research Articles

Investigation on the relationship between the surface texture index and the surface free energy of aggregate

The surface free energy (SFE) of aggregate and asphalt binder can be utilized to quantify the adhesion between the aggregate and binder. The SFE value varies with the changing surface characteristics. This study investigated the effect of surface texture on the aggregate’s SFE when applying the contact angle measurement. A surface treatment protocol for granite, diabase, basalt, and limestone was designed. A dicing saw, grinder and abrasive paper were utilized and were combined into three groups to treat the aggregates’ surface — Groups A, B, and C. The group in which aggregate was not treated was labeled Group D. The aggregate image measurement system (AIMS) was employed to quantify the surface characteristic. After surface treating, four levels of surface texture index were obtained. The surface texture indexes of the treated aggregates followed an increasing rank: A < B < C < D. A higher surface texture index indicated higher surface roughness. Subsequently, the sessile drop method was utilized to measure the contact angle and obtain the SFE of the aggregates that been treated through Groups A, B, and C. The gas adsorption method was applied to determine the SFE of aggregates in Group D. With the increasing surface texture index, the contact angle also increased and resulted in an increasing SFE value. An exponential-type model was established to describe the relationship between surface texture index and SFE. The model was first employed to fit the SFE data of aggregates in the A, B, C, and D groups, which showed good satisfaction of model fitting. The model was also applied to fit the SFE data of aggregates in the A, B, and C groups and to predict the SFE values based on the surface texture index obtained in Group D, which indicated good predictability. The fitting parameters showed a variable coefficient within 20% in the two fitting methods, which confirmed the model was reliable.

Surface free energy, wettability and bonding of plywood after fire-retardant treatment with various chemicals

Plywood usage has been increasing recently in the building and furniture industry due to its outstanding surface and resistance properties. Although it has many advantages, the flammability of plywood needs to be improved with fire-retardant chemicals. However, these chemicals which improve panels against burning can be differently influenced many properties of panels. This study aimed to investigate the surface roughness, wettability, and surface free energy of the veneers treated with some fire-retardant chemicals and to determine the changes in the mechanical properties of plywood. The beech, poplar, alder, and pine veneers were used as wood species whilst zinc borate, borax, monoammonium phosphate, and ammonium sulfate were used as fire-retardant chemicals in this study. The surface roughness and contact angle measurements were performed to determine the surface properties of veneers, and then the surface free energy values were calculated. The bonding and bending strength of the plywood panels produced from these veneers were determined according to the relevant standards. As a result of the study, the surface free energy values of veneers with lower contact angles and smoother surfaces were found to be higher. It was also determined that the bonding strength values of plywood panels produced from veneers with high surface energies were also high. Generally, the untreated veneers had higher surface free energy values than the treated veneers. Among the fire-retardant chemicals, zinc borate caused the highest surface free energy values in the beech and alder veneers while borax exhibited the highest values in the poplar and pine veneers.

Influence of Selected Ophthalmic Fluids on the Wettability and Hydration of Hydrogel and Silicone Hydrogel Contact Lenses-In Vitro Study.

This study attempts to evaluate the effect of incubation in selected ophthalmic fluids on contact lenses (Etafilcon A, Omafilcon A, Narafilcon A, Senofilcon A). Four research groups differing in the incubation environment were created: (1) initial state, (2) contact lens solution (CLS), (3) contact lens solution and eye drops (ED) and (4) eye drops. Dehydration by gravimetric method and the contact angle (CA) by the sessile drop method were tested. The surface free energy (SFE) was also calculated with the use of several methods: Owens–Wendt, Wu, Neumann, and Neumann–Kwok. The greatest changes in the dehydration profile were observed for contact lenses incubated in ED. The most noticeable changes in CA values were observed for contact lenses incubated in ED, in which it was not possible to settle water drop after incubation. On the basis of SFE analysis, higher values were found for hydrogel contact lenses, e.g., according to the Owens–Wendt method, they ranged from 54.45 ± 6.56 mJ/m to 58.09 ± 4.86 mJ/m, while in the case of silicone-hydrogel contact lenses, they ranged from 32.86 ± 3.47 mJ/m to 35.33 ± 6.56 mJ/m. Incubation in all tested environments decreased the SFE values, but the differences were in most cases statistically insignificant. Calculating the SFE may be a useful method as it can be used to estimate the possibility of bacteria adhering to contact lens surfaces.

Using contact angle measurement technique for determination of the surface free energy of B-SBA-15-x materials

Pure and boron-containing, Santa Barbara Amorphous (SBA-15) mesoporous materials and B-SBA-15-x (x is molar ratio of Si/B = 50, 30, 10), were synthesized via a direct hydrothermal method. Samples were characterized by XRD, BJH pore size distribution and SEM techniques. A contact angle technique was used to determine surface free energy and its dispersive and polar components. For this purpose, ethylene glycol (EG), di-iodomethane (DIM), formamide (FA) and water were used as model liquids to detect the contact angles. The OWRK/Fowkes approach was used to calculate the surface free energy values. Total surface free energy (γS) values of pure SBA-15 and B-SBA-15-50, B-SBA-15-30, B-SBA-15-10 were calculated as 64.365, 63.545, 63.490 and 64.218 mJ/m2 at room temperature, respectively. The main results of the study can be summarized as follows: (i) The contact angle measurement technique is suitable for determining the total surface free energy (γS) and its dispersive and polar components (γSd and γSp, respectively) of SBA-15 mesoporous materials and (ii) Addition of boron did not have a significant impact on the characteristic structure of SBA-15.

Zein-Based Films Containing Monolaurin/Eugenol or Essential Oils with Potential for Bioactive Packaging Application.

Zein is renewable plant protein with valuable film-forming properties that can be used as a packaging material. It is known that the addition of natural cross-linkers can enhance a film’s tensile properties. In this study, we aimed to prepare antimicrobial zein-based films enriched with monolaurin, eugenol, oregano, and thyme essential oil. Films were prepared using the solvent casting technique from ethanol solution. Their physicochemical properties were investigated using structural, morphological, and thermal techniques. Polar and dispersive components were analyzed using two models to evaluate the effects on the surface free energy values. The antimicrobial activity was proven using a disk diffusion method and the suppression of bacterial growth was confirmed via a growth kinetics study with the Gompertz function. The films’ morphological characteristics led to systems with uniform distribution of essential oils or eugenol droplets combined with a flat-plated structure of monolaurin. A unique combination of polyphenolic eugenol and amphiphilic monoglyceride provided highly stretchable films with enhanced barrier properties and efficiency against Gram-positive and Gram-negative bacteria, yeasts, and molds. The prepared zein-based films with tunable surface properties represent an alternative to non-renewable resources with a potential application as active packaging materials.

Towards physical and mechanical properties of the novel Al-Cr-Ni-Fe decagonal quasicrystal and crystalline approximants

In the present article, mechanically alloyed AlCrNiFe alloy powders, including quasicrystalline and crystalline phases, were compacted through a cold isostatic pressing at 400 MPa pressure, 25 °C temperature, and 1 h soaking time. The main objective of this work is to examine the surface porosity and relative density, microhardness, compressive strength, wettability, electrical resistivity, and optical and luminescence properties of the AlCrNiFe compacts. The effect of the crystalline/quasicrystalline structures on the mentioned properties was studied. It should be noted that the physical and mechanical characteristics of the AlCrNiFe alloys were first investigated. It was diagnosed that the Vickers microhardness of the decagonal quasicrystalline compacts possesses the maximum value of 12 GPa. The AlCrNiFe compacts containing the decagonal phase acquire the maximum compressive strength and low ductility of 363 MPa and 2.53%, respectively. The highest contact angle value (θavg = 103.3° ± 2.3°) beside the lowest wettability and surface free energy values (WA = 56.1 ± 2.8 mJ m−2, SFE = 21.1 ± 1.3 mJ m−2) belongs to the decagonal quasicrystal as compared to the PTFE. It was recognized that the presence of the decagonal quasicrystal resulted in the high electrical resistivity value of 930 μΩcm at room temperature with a negative temperature coefficient of resistivity (ρ−253/ρ27 = 1.13). Decagonal quasicrystal comprises the highest optical absorption and bandgap, which made it suitable for solar-selective absorbers.

Estimation of the surface free energy and moisture susceptibility of asphalt mastic and aggregate system containing salt storage additive

The moisture susceptibility of asphalt mixtures containing salt storage additive is a focus. The objective of this study was to characterize adhesion characteristic of asphalt-aggregate system containing salt storage additive. The contact angle test and boiling water test were carried out to obtain the contact characteristics and stripping behaviour of them. The results indicate that the contact angle values of asphalt mastic increased with the increment of salt storage additive resulting in poor wettability. And the surface free energy values of asphalt mastic slightly reduced with increased salt storage additive, and were remarkably less than that of water leading to bad affinity with stone under moisture condition. The adhesion works under moisture condition mainly depended on stone lithology, and had good negative correlation with the stripping area ratio values from boiling water test.

Determination of the surface characteristics of medium density fibreboard processed with CNC machine and optimisation of CNC process parameters by using artificial neural network

The objective of this study is to determine the surface characteristics such as surface roughness, wettability and surface free energy of medium density fibreboard (MDF) processed with CNC machine and to optimise CNC process parameters by using artificial neural network (ANN). In the study, the cutting tools with three different diameters (6 mm, 8 mm and 10 mm), four different spindle speed values (12,500 rpm, 15,000 rpm, 17,500 rpm and 20,000 rpm) and three different feed rate values (2 m/min, 6 m/min and 10 m/min) were used as CNC processing parameters. In order to determine the surface characteristics of the specimens, surface roughness and contact angle measurements were performed and surface free energy values were calculated according to one of the methods mentioned in the literature. The surface roughness and surface free energy data obtained from experimental studies were analysed with ANN and modelled. The prediction models with the best performance and acceptable deviations were determined by using statistical and graphical comparisons between the experimental data and the prediction values obtained as a result of ANN analysis. By using these prediction models, the data was obtained according to the CNC parameters not used in the experimental study. According to the experimental results, the surface roughness values decreased with increasing the cutting tool diameter and feed rate while the values increased with increasing the spindle speed. Similarly, the highest surface free energy values were generally obtained from the high spindle speed, the low tool diameter and feed rate values. The optimum values of tool diameter, spindle speed and feed rate for the surface roughness values were determined as 6 mm, 20,000 rpm and 2 m/min whilst these values for the surface free energy values were determined as 6 mm, 16,500 rpm, 2 m/min, respectively. The findings of this study could be employed effectively to reduce time, energy and cost for experimental investigations in the interior decoration and furniture industry.

A comparative study of the interaction between the dried ink layer andPLAfilm used for packaging purposes

AbstractThis research aims at comparing the interactions between the water‐based printing ink and polylactide (PLA) printing base. As a reference base, a polyethylene terephthalate (PET) film was chosen. The wettability of both films was investigated. The Owens–Wendt method was applied to calculate the surface free energy (SFE). The values of SFE and its polar and dispersive components were compared with the surface tension (ST) of the ink and the polar and dispersive components of ST. The wetting envelopes of the investigated PLA and PET films are presented. Finally, the bonding strength between the dried ink layer and the printing base was analyzed. The PET film exhibited higher values of SFE. However, the bonding strength between the dried ink layer and the printing base was higher for PLA films. Our results reveal that PLA films can be an excellent choice as packaging materials, with comparable or even better print quality than conventional fossil‐based plastics.

Effect of Plasma Surface Modification on Print Quality of Biodegradable PLA Films

PLA films, as non-absorbent materials, require modification of the surface before the printing process in order to improve the wettability of the substrate and to obtain proper ink adhesion to the substrate. In this paper, the surfaces of two kinds of PLA films were modified using plasma activation with parameters enabling high surface free energy (SFE) values, and then the films were printed on using different kinds of flexographic inks. Two gases, oxygen and argon, were used for activation, as these make it possible to obtain good hydrophilicity and high SFE values while having different effects on the roughness, or the degree of surface etching. Plasma-activated films were subsequently subjected to the measurements of: contact angle with water, diiodomethane and three printing inks, roughness, weight change, strength properties, color and gloss change, and SFE was determined. Unmodified and activated films were flexographically printed in laboratory conditions and then the quality of obtained prints was analyzed. The results showed a strong effect of activation with both oxygen and argon plasma on the SFE value of the films and the contact angles of water and inks, with the gas used for plasma activation and the type of film significantly influencing the thickness of the fused ink layer and the resultant color. Moreover, plasma activation had a especially favorable and significant effect on the quality of prints made with water-based inks, while it had little effect when printing with solvent-based inks.

Influence of Consistency and Composition of Growth Medium on Surface Physicochemical Properties of Streptomyces

Streptomyces are known for their ability to produce various secondary metabolites used in biotechnology, human medicine and agriculture. Understanding of surface properties is very interesting in the control of interfacial phenomena. The objective of this study was to investigate the effect of consistency and composition of growth medium on the physicochemical properties of the surface of Streptomyces strains. To achieve this objective, Six Streptomyces strains belonging to bioprocess and bio-interfaces laboratory are cultivated in two media Bennett (rich) and GBA (minimum). Both media are tested in solid (agar) and liquid (broth) mode. The wettability θw, electron donor character ˠ (-), electron acceptor character ˠ (+) and Surface free energy ΔGiwi are determined using contact angle measurements. On the two solid media Bennett and GBA, Streptomyces strains develop a hydrophobic surface (96.9° &lt;θw&lt;167.9°) with a weak electron donor character (0.3 mJm-2 &lt; (ˠ (-)) &lt;12.14 mJm-2) and a strong electron acceptor character (0.26 mJm-2 &lt; ˠ (+) &lt; 17.8 mJm-2) and a negative surface free energy ((- 11.8 mJm-2) &lt; ΔGiwi &lt; (-110 mJm-2)). Whereas on both Bennett and GBA liquid media, the surfaces of Streptomyces strains are generally hydrophilic (1.3° &lt; θw &lt; 9.33°) with a strong electron donor character (13.76 mJm-2 &lt; ( ˠ (-)) &lt; 70.06 mJm-2) and a positive surface free energy. By changing the composition of the culture medium, only a slight change in the degree of hydrophobicity and surface free energy of Streptomyces is observed. Regarding the effect of medium composition on the surface properties of Streptomyces, the degree of wettability and the values of surface free energy are no longer the same when the composition of the medium changes. These results could be applied in further studies interested in interfacial phenomena and microbial adhesion in biotechnological fields.

Adhesion study of biocompatible polyhedral oligomeric silsesquioxane - Poly(carbonate-urea) urethane coating on Stainless Steel 316L in the presence of an amino-silane primer

One of the challenges of using Stainless Steel 316L (SS316L) as an implant substrate is poor adhesion of organic/inorganic coatings on their surface. Poor adhesion of the provided coating may lead to serious problems like blockage of arteries in cardiovascular stents. In this study, the (3-aminopropyl) triethoxysilane effect as an adhesion promoter between the organic/inorganic polyhedral oligomeric silsesquioxane - poly(carbonate-urea) Urethane (POSS-PCU) coating and substrate was investigated. The objective was to study the significant parameters, including the surface preparation method, pH of the silane layer, and the curing process on adhesion of the coating on the SS316L.Contact angle measurements indicated that the higher surface free energy values attributed to the pretreated silane layer did not result in better adhesion strength of POSS-PCU coating. Scanning Electron Microscope/Energy Dispersive Using X-Ray and Atomic Force Microscopy results revealed that more uniformity was obtained in silane layers prepared at pH= 4 (acidic solution) compared to higher pH values. The ellipsometry results showed that the acidic silane solution, which was cured at high temperature, had a lower thickness than other primer layers. Lap-shear strength results confirmed a noticeable increase in the adhesion strength of POSS-PCU coating on the SS316L substrate in the presence of the silane layer in dry and wet conditions.

Surface free energy and wettability properties of transparent conducting oxide-based films with Ag interlayer

ITO, ZTO, AZO and Ag are commonly used in transparent conducting oxide (TCO)/metal/TCO electrodes to form multilayered thin films on a suitable substrate. A detailed surface free energy (SFE) knowledge of these films is critical to design desirable TCO-based sandwich structures. In this study, TCO/Ag/TCO multilayer thin films were coated onto glass substrates using ITO, ZTO, AZO and Ag targets by magnetron sputtering. The wettability properties of TCO, Ag interlayer and TCO/Ag/TCO were evaluated by contact angle measurements of seven different liquids having various surface tension values. The dispersive and polar components of SFE were calculated using geometric and harmonic mean approaches. The acidic and basic components of SFE were calculated using van Oss-Chaudhury-Good method. Following this, the work of adhesion values between TCO films and Ag interlayer were estimated using SFE values of the films. The results show that the SFE components of the surfaces differ depending on the TCO type, the total SFE values of TCO/Ag/TCO films were lower than that of TCO films, and AZO/Ag adhesion is stronger than the other TCO/Ag structures. The reasons behind these differences were discussed by evaluating the SFE, XRD, AFM and SEM analysis simultaneously.

Hydrophobically modified cotton fabric assisted separation of oil-water mixture.

Superhydrophobic-superoleophilic fabrics were prepared and evaluated for oil-water mixture separation efficiencies. The nano-TiO2 and nano-SiO2 based coatings were done on the surface of the cotton fabric to create nanoscale roughness over the surface which was further modified by low energy material 1, 1, 3, 3-Hexamethyldisilazane (HMDS) and, polydimethylsiloxane (PDMS). Particle size and stability of prepared sol were characterized by particle size analysis and zeta potential. Coated cotton fabric samples were characterized by contact angle, contact angle hesteresis and surface free energy for its hydrophobic nature. Surface morphology was studied by scanning electron microscopy (SEM). The coated fabrics were found to be hydrophobic with low surface free energy values. The maximum contact angle was found to be 133° and lowest contact angle hysteresis was 5°. SEM confirmed the appearance of nanoscale surface roughness after coating of sols on cotton fabric. The average particle size and zeta potential values of silica sol was 61 nm and 137 mv whereas for titania sol it was found 344 nm and 200 mv, respectively. The oil-water separation efficiency of coated fabric was also observed by a different oil-water mixture. The coatings were found to be hydrophobic in nature and seem to be very useful for oil-water mixture separation.

A New View of a:C-H-coated Ti-6Al-4V Alloy to be Used as Orthopedic Implants: Influence of Surface Free-energy of Interaction on the Biological Responses

In a previous published work, the Ti-6Al-4V alloy were functionalized by using plasma enhanced chemical vapour deposition (PECVD) process in order to obtain hydrogenated amorphous carbon (a:C-H) on the biomaterial's surface. At the time, we noticed the functionalized surface contributed to the advance of using Ti-6Al-4V in biomedical implants applications as well as in the adding of intrinsic properties as demonstrated by electrochemical and biological assays. Here, we present new view of a-C:H-coated Ti-6Al-4V alloy, considering the influence of surface free-energy of interaction and understanding how the surface influences the biological response using pre-osteoblastic cells (MC3T3-61). Our results demonstrate, the Ti-6Al-4V containing a:C-H film has less negative value of surface free-energy when compared to the bare material (-22.156 mJ m -2 vs. -60.046 mJ m -2 ), suggesting a tendency toward to a less hydrophobic surface which is extremely important to reduce the inflammatory process, common in orthopedic implants. DOI: http://dx.doi.org/10.17807/orbital.v13i3.1622

Conversion of Polymer Surfaces into Nonwetting Substrates for Liquid Metal Applications.

Liquid metal-based applications are limited by the wetting nature of polymers toward surface-oxidized gallium-based liquid metals. This work demonstrates that a 120 s CF4/O2 plasma treatment of polymer surfaces-such as poly(dimethylsiloxane) (PDMS), SU8, S1813, and polyimide-converts these previously wetting surfaces to nonwetting surfaces for gallium-based liquid metals. Static and advancing contact angles of all plasma-treated surfaces are >150°, and receding contact angles are >140°, with contact angle hysteresis in the range of 8.2-10.7°, collectively indicating lyophobic behavior. This lyophobic behavior is attributed to the plasma simultaneously fluorinating the surface while creating sub-micron scale roughness. X-ray photoelectron spectroscopy (XPS) results show a large presence of fluorine at the surface, indicating fluorination of surface methyl groups, while atomic force microscopy (AFM) results show that plasma-treated surfaces have an order of magnitude greater surface roughness than pristine surfaces, indicating a Cassie-Baxter state, which suggests that surface roughness is the primary cause of the nonwetting property, with surface chemistry making a smaller contribution. Solid surface free energy values for all plasma-treated surfaces were found to be generally lower than the pristine surfaces, indicating that this process can be used to make similar classes of polymers nonwetting to gallium-based liquid metals.

Performance matching between the surface structure of cucumber powdery mildew in different growth stages and the properties of surfactant solution.

Understanding performance matching of pesticide droplets on the surface of cucumber leaves modified by powdery mildew is of practical importance for the agricultural sector. Here, the surface texture and wettability of cucumber leaves covered by powdery mildew were systematically examined using parameters such as micromorphology, physicochemical properties, and liquid droplet contact angle measurements. Our results show that powdery mildew growth can be divided into four distinct stages according to the surface texture characteristics of the diseased cucumber leaves. The three-dimensional (3D) surface structures of powdery mildew layers on cucumber leaves had individual characteristics at different mildew growth stages, among which powdery mildew was more easily spread in the last growth stage, and powdery mildew height was greatest in the NO. 2 growth stage (Sa =425.35 μm). Surface free energy values, static contact angle, and contact angle hysteresis all correlated strongly with the surface characteristics of powdery mildew layers at different growth stages. When the concentration of surfactant reached the critical micelle concentration, the wetting state of AEO-5 solution droplets on the surface of cucumber powdery mildew leaves reached the Wenzel state more easily. The wettability of a droplet on the leaf surface depends on the state of the monomer and micelle in the surfactant solution and the surface characteristics of the powdery mildew-covered leaf. The 3D structure and relative dielectric constant of powdery mildew-covered leaves influenced surface texture characteristics, which in turn controlled the wetting and matching ability of surfactant droplets on diseased leaves. This work provides valuable new insights into the matching of the structure of powdery mildew-covered plant leaves with the properties of surfactant solutions. © 2021 Society of Chemical Industry.

Influence of Surface Characteristics of Different Implant Abutment Materials on Growth of Porphyromonas Gingivalis

The purpose of the present study was to determine the surface physicochemical properties of polished implant abutment materials and to investigate their relationship with the growth of Porphyromonas gingivalis in vitro. Four groups of the most popular prosthetic materials were used in this study: titanium alloy (Ti), yttria-stabilized zirconium oxide (3Y-TZP), polyether ether ketone (PEEK) composite, and poly(methyl methacrylate) (PMMA). The plate shape specimens (10 × 10 × 0.5 mm) were polished by applying sequential mechanical polishing. Measurements of water contact angle (WCA), surface free energy (SFE) and roughness were performed. Also, the growth of P.gingivalis was measured via counting colony-forming units to milliliter (CFUs/mL). The WCA means were significantly different among all groups, and the highest hydrophilicity was observed on the PEEK, whereas the lowest on PMMA surface. All measured surfaces had similarly low SFE values, but Ti, 3Y-TZP, and PEEK demonstrated more expressed polar parts. All means of roughness were beyond the micro-level and were lower than 0.2 µm. The highest CFUs/mL was assessed on the PMMA and it was significantly different from others, whereas the lowest was on 3Y-TZP. The surface roughness had a significant impact on CFUs/mL growth.

Influence of Non-Thermal Atmospheric Pressure Plasma Treatment on Retentive Strength between Zirconia Crown and Titanium Implant Abutment.

The aim of this study is to investigate the effect of non-thermal atmospheric pressure plasma (NTP) on retentive strength (RS) between the zirconia crown and the titanium implant abutment using self-adhesive resin cement. Surface free energy (SFE) was calculated on 24 cube-shaped zirconia blocks, and RS was measured on 120 zirconia crown-titanium abutment assemblies bonded with G-CEM LinkAce. The groups were categorized according to the zirconia surface treatment as follows: Control (no surface treatment), NTP, Si (Silane), NTP + Si, Pr (Z-Prime Plus), and NTP + Pr. Half of the RS test assemblies were aged by thermocycling for 5000 cycles at 5–55 °C. The SFE was calculated using the Owens-Wendt method, and the RS was measured using a universal testing machine at the maximum load until failure. One-way analysis of variance (ANOVA) with post-hoc Tukey honestly significant difference (HSD) was performed to evaluate the effect of surface treatments on the SFE and RS. Independent sample t-test was used to compare the RS according to thermocycling (p < 0.05). For the SFE analysis, the NTP group had a significantly higher SFE value than the Control group (p < 0.05). For the RS test, in non-thermocycling, the NTP group showed a significantly higher RS value than the Control group (p < 0.05). However, in thermocycling, there was no significant difference between the Control and NTP groups (p > 0.05). In non-thermocycling, comparing with the NTP + Si or NTP + Pr group, there was no significant difference from the Si or Pr group, respectively (p > 0.05). Conversely, in thermocycling, the NTP + Si and NTP + Pr group had significantly lower RS than the Si and Pr group, respectively (p < 0.05). These results suggest that NTP single treatment for the zirconia crown increases the initial RS but has little effect on the long-term RS. Applied with Silane or Z-Prime Plus, NTP pre-treatment has no positive effect on the RS.

Surface energy evaluation of casting and nanofiber polyurethane films by using different models

AbstractThe components of the surface free energy (SFE) were determined from static contact angle measurements of five liquids using different methods. The two manufacturing techniques (casting and electrospinning) applied to obtain polyurethane (PU) membranes give surfaces with different wetting properties. The SFE data varied and were strongly dependent on calculations methods and liquids that were used for contact angle measurements. As a whole, the SFE of electrospun PU membrane (PU‐N) (~24 mN/m) was slightly higher than that of casting PU membrane (PU‐F) (~18 mN/m) with similar chemical compositions. The overall increase in the value of SFE is mainly due to the microstructures with increased surface area and modulations of nanofibers. The results evidence the impact of the PU membrane preparation on the properties of the biomaterial surface. Such structure–properties–function relationship is necessary to lay the groundwork for establishing a set of design criteria to guide the fabrication of synthetic materials.