Search Results (31)

The fluororesin membrane emerges as an ideal chemical-protective clothing material due to its excellent permeation resistance. However, using a fluororesin membrane with a low surface energy for compounding fabrics is very challenging. Herein, we demonstrate a strategy to modify the surface of a poly(ethylene-alt-tetrafluoroethylene) (ETFE) membrane by the atmospheric pressure dielectric barrier discharge (DBD) of plasma under different working voltages, processing times, and concentrations of acrylic acid (AA) in a helium (He) atmosphere. The increase in the hydrophilicity of the ETFE membrane is confirmed by the wettability test, which shows a significant decrease in the water contact angle, from 96° to 50°, after plasma modification. The interfacial T-peel strength of an ETFE membrane composited with polyester fabric increased from 0.53 N/cm to 13.64 N/cm after plasma modification. Significantly, the T-peel strength of the composite using a modified ETFE membrane with ultrasonic washing could still reach 11.75 N/cm. Various characterization methods clearly disclosed the physical and chemical changes on the ETFE membrane surface, such as introducing the polar -COOH group at a nano-level, improving the roughness, decreasing the ratios of the F/C element, and increasing the ratios of the O/C element, suggesting using nano-level grafted polyacrylic acid (g-PAA) on the surface of the membrane by DBD. Full article

This study examines the static performances of a graphene platelet (GPL)-reinforced ethylene tetrafluoroethylene (ETFE) composite membrane under wind loadings. The wind pressure distribution on a periodic tensile membrane unit was analyzed by using CFD simulations, which considered various wind velocities and directions. A one-way fluid–structure interaction (FSI) analysis incorporating geometric nonlinearity was performed in ANSYS to evaluate the static performances of the composite membrane. The novelty of this research lies in the integration of graphene platelets (GPLs) into ETFE membranes to enhance their static performance under wind loading and the combination of micromechanical modelling for obtaining material properties of the composites and finite element simulation for examining structural behaviors, which is not commonly explored in the existing literature. The elastic properties required for the structural analysis were determined using effective medium theory (EMT), while Poisson’s ratio and mass density were evaluated using rule of mixtures. Parametric studies were carried out to explore the effects of a number of influencing factors, including pre-strain, attributes of wind, and GPL reinforcement. It is demonstrated that higher initial strain effectively reduced deformation under wind loads at the cost of increased stress level. The deformation and stress significantly increased with the increase in wind velocity. The deflection and stress level vary with the wind direction, and the maximum values were observed when the wind comes at 15° and 45°, respectively. Introducing GPLs with a larger surface area into membrane material has proven to be an effective way to control membrane deformation, though it also results in a higher stress level, indicating a trade-off between deformation management and stress management. Full article

This study presents a numerical investigation of the dynamic behavior of graphene platelet (GPL)-reinforced ethylene tetrafluoroethylene (ETFE) tensile membrane structures subjected to harmonic excitation. Modal and harmonic response analyses were performed to assess both the natural frequencies and the dynamic responses of the ETFE membrane. GPLs were employed as the reinforcements to enhance the mechanical properties of the membrane materials, whose Young’s modulus was predicted through the effective medium theory (EMT). Parametric studies were conducted to examine the impact of pre-strain and the attributes of the GPL reinforcements, including weight fraction and aspect ratio, on the natural frequencies and amplitude–frequency response curves of the membrane structure. The first natural frequency substantially increased from 5.46 Hz without initial strain to 31.0 Hz with the application of 0.1% initial strain, resulting in a frequency shift that moved the natural frequency out of the range of typical wind-induced pulsations. Embedding GPL fillers into ETFE membrane was another potential solution to enhance the dynamic stability of the membrane structure, with a 1% addition of GPLs resulting in a 48.6% increase in the natural frequency and a 45.1% reduction in resonance amplitude. GPLs with larger aspect ratios provided better reinforcement, offering a means to fine-tune the membrane’s dynamic response. These results underscore that by strategically adjusting both pre-strain levels and GPL characteristics, the membrane’s dynamic behavior can be optimized, offering a promising approach for improving the stability of structures subjected to wind-induced loads. Full article

The 6935M Sprint Quattro Secure S and 6947M Sprint Quattro Secure are high voltage leads designed to administer a maximum of 40 joules of energy for terminating ventricular tachycardia or ventricular fibrillation. Both leads utilize silicone insulation and a polyurethane outer coating. The inner coil is shielded with polytetrafluoroethylene (PTFE) tubing, while other conductors are enveloped in ethylene tetrafluoroethylene (ETFE), contributing to the structural integrity and functionality of these leads. Polyurethane is a preferred material for the outer insulation of cardiac leads due to its flexibility and biocompatibility, while silicone rubber ensures chemical stability within the body, minimizing inflammatory or rejection responses. Thirteen implantable cardioverter defibrillator (ICD) leads were obtained from the Wright State University Anatomical Gift Program. The as-received devices exhibited varied in vivo implantation durations ranging from less than a month to 89 months, with an average in vivo duration of 41 ± 27 months. Tests were conducted using the Test Resources Q series system, ensuring compliance with ASTM Standard D 1708-02a and ASTM Standard D 412-06a. During testing, a load was applied to the intact lead, with careful inspection for surface defects before each test. Results of load to failure, percentage elongation, percentage elongation at 5 N, ultimate tensile strength, and modulus of elasticity were calculated. The findings revealed no significant differences in these parameters across all in vivo exposure durations. The residual properties of these ICD leads demonstrated remarkable stability and performance over a wide range of in vivo exposure durations, with no statistically significant degradation or performance changes observed. Full article

During the production of a PolyTetraFluoroEthylene(PTFE) emulsion, it is crucial to detect the separation between the PTFE emulsion and liquid paraffin in order to purify the PTFE emulsion and facilitate subsequent polymerization. However, the current practice heavily relies on visual inspections conducted by on-site personnel, resulting in not only low efficiency and accuracy, but also posing potential threats to personnel safety. The incorporation of artificial intelligence for the automated detection of paraffin separation holds the promise of significantly improving detection accuracy and mitigating potential risks to personnel. Thus, we propose an automated detection framework named PatchRLNet, which leverages a combination of a vision transformer and reinforcement learning. Reinforcement learning is integrated into the embedding layer of the vision transformer in PatchRLNet, providing attention scores for each patch. This strategic integration compels the model to allocate greater attention to the essential features of the target, effectively filtering out ambient environmental factors and background noise. Building upon this foundation, we introduce a multimodal integration mechanism to further enhance the prediction accuracy of the model. To validate the efficacy of our proposed framework, we conducted performance testing using authentic data from China’s largest PTFE material production base. The results are compelling, demonstrating that the framework achieved an impressive accuracy rate of over 99% on the test set. This underscores its significant practical application value. To the best of our knowledge, this represents the first instance of automated detection applied to the separation of the PTFE emulsion and paraffin. Full article

The development of renewable energy sources has grown increasingly as the world shifts toward lowering carbon emissions and supporting sustainability. Solar energy is one of the most promising renewable energy sources, and its harvesting potential has gone beyond typical solar panels to small, portable devices. Also, the trend toward smart buildings is becoming more prevalent at the same time as sensors and small devices are becoming more integrated, and the demand for dependable, sustainable energy sources will increase. Our work aims to tackle the issue of identifying the most suitable protective layer for small optical devices that can efficiently utilize indoor light sources. To conduct our research, we designed and tested a model that allowed us to compare the performance of many small panels made of monocrystalline cells laminated with three different materials: epoxy resin, an ethylene–tetrafluoroethylene copolymer (ETFE), and polyethylene terephthalate (PET), under varying light intensities from LED and CFL sources. The methods employed encompass contact angle measurements of the protective layers, providing insights into their wettability and hydrophobicity, which indicates protective layer performance against humidity. Reflection spectroscopy was used to evaluate the panels’ reflectance properties across different wavelengths, which affect the light amount arrived at the solar cell. Furthermore, we characterized the PV panels’ electrical behavior by measuring short-circuit current (I_SC), open-circuit voltage (V_OC), maximum power output (P_max), fill factor (FF), and load resistance (R). Our findings offer valuable insights into each PV panel’s performance and the protective layer material’s effect. Panels with ETFE layers exhibited remarkable hydrophobicity with a mean contact angle of 77.7°, indicating resistance against humidity-related effects. Also, panels with ETFE layers consistently outperformed others as they had the highest open circuit voltage (V_OC) ranging between 1.63–4.08 V, fill factor (FF) between 35.9–67.3%, and lowest load resistance (R) ranging between 11,268–772 KΩ.cm⁻² under diverse light intensities from various light sources, as determined by our results. This makes ETFE panels a promising option for indoor energy harvesting, especially for powering sensors with low power requirements. This information could influence future research in developing energy harvesting solutions, thereby making a valuable contribution to the progress of sustainable energy technology. Full article

Plastic films utilized as greenhouse coverings play a vital role in safeguarding plantations from diverse weather conditions like sunlight, rain, hail, and wind. It is essential for these films to preserve their properties even after extended exposure to sunlight and water, while also maintaining transparency to support the unhindered growth of plants. The purpose of the study was to compare the properties of three types of plastic films: low density polyethylene diffuse film, low density polyethylene clear film, and ethylene tetrafluoroethylene film, before and after their ageing in weather test chamber with xenon-arc light in the presence of moisture. Two distinct types of PE films were chosen based on their suitability for specific regions in Croatia, whereas ETFE film was chosen as a potential new material that is gaining popularity across various industries, including agriculture. The properties investigated were tensile properties, transmittance by spectral analysis, and viscoelastic properties by dynamic mechanical analysis. Also, untreated films and the ones exposed to artificial ageing were compared by means of Fourier-transform infrared spectroscopy, differential scanning calorimetry and thermogravimetric analysis. The administered tests revealed a certain level of property degradation due to ageing in all three films. However, none of the films showed a substantial level of deterioration, indicating their suitability as greenhouse coverings. Full article

In this work, the novel design of a sliding mode TriboElectric Nano Generator (TENG)—which can utilize vibration amplitude of a few hundred microns to generate useful electric power—is proposed for the first time. Innovative design features include motion modification to amplify relative displacement of the TENG electrodes and use of biological material-based micron-sized powder at one of the electrodes to increase power output. The sliding mode TENG is designed and fabricated with use of polyurethane foam charged with the biological material micropowder and PolyTetraFluoroEthylene (PTFE) strips as the electrodes. Experimentations on the prototype within frequency range of 0.5–6 Hz ensured peak power density of 0.262 mW/m², corresponding to the TENG electrode size. Further numerical simulation is performed with the theoretical model to investigate the influence of various design parameters on the electric power generated by the TENG. Lastly, application of the proposed TENG is demonstrated in a wearable device as an in-shoe sensor. Conceptual arrangement of the proposed in-shoe sensor is presented, and numerical simulations are performed to demonstrate that the real size application can deliver peak power density of 0.747 mW/m² and TENG; the voltage will accurately represent foot vertical force for various foot force patterns. Full article

A composite proton conducting membrane (PCM) was prepared by radiation-induced grafting (RIG) of binary mixtures of 4-vinyl pyridine (4-VP) and 1-vinylimidazole (1-VIm) onto poly(ethylene-co-tetrafluoroethylene) (ETFE) film followed by phosphoric acid (PA) doping. The grafting parameters such as absorbed dose, temperature, monomer concentration, time, and monomer ratio were varied to control the degree of grafting (DG%). The effect of the reactivity ratio of 4-VP and 1-VIm on the composition and degree of monomer unit alternation in the formed graft copolymer was investigated. The changes in the chemical and physical properties endowed by grafting and subsequent PA acid doping were monitored using analytical instruments. The mechanical properties and proton conductivity of the obtained membrane were evaluated and its performance was tested in H₂/O₂ fuel cell at 120 °C under anhydrous and partially wet conditions. The acid doping level was affected by the treatment parameters and enhanced by increasing DG. The proton conductivity was boosted by incorporating the combination of pyridine and imidazole rings originating from the formed basic graft copolymer of 4-VP/1-VIm dominated by 4-VP units in the structure. The proton conductivity showed a strong dependence on the temperature. The membrane demonstrated superior properties compared to its counterpart obtained by grafting 4-VP alone. The membrane also showed a strong potential for application in proton exchange membrane fuel cells (PEMFC) operating at 120 °C. Full article

Condensation of the reaction between enrofloxacin and ethylenediamine in the existence of glacial acetic acid produced a new N,N-ethylene (bis 1-cyclopropyl-7-(4-ethylpiperazin-1-yl)-6-fluoro-1,4-dihydroquinoline-3-carboxylic acid Schiff base (H₂Erx-en). H₂Erx-en was used as a tetra-dentate ligand to produce novel complexes by interacting with metal ions iron(III), yttrium(III), zirconium(IV), and lanthanum(III). The synthetic H₂Erx-en and its chelates had been detected with elemental analysis, spectroscopic methods, mass spectrometry, thermal studies, conductometric and magnetic measurements experiments. The calculated molar conductance of the complexes in 1 × 10⁻³ M DMF solution shows that iron(III), yttrium(III) and lanthanum(III) are 1:1 electrolytes, however the zirconium(IV) complex is non-electrolyte. The infrared spectra of H₂Erx-en chelates indicated that the carboxylic group is deprotonated and H₂Erx-en is associated with metals as a tetra-dentate through nitrogen and oxygen atoms. The disappearance of the carboxylic proton in all complexes corroborated information concerning H₂Erx-en deprotonation and complexation with metal ions, according to ¹H NMR data. Thermal analysis revealed the abundance of H₂O particles in the chelates’ entrance and outlet spheres, indicating the disintegration pattern of H₂Erx-en and their chelates. The Coats–Redfern and Horowitz–Metzeger approaches were utilized to calculate the thermodynamic items (E_a, ΔS *, ΔH *, and ΔG *) at n = 1 and n ≠ 1. The resulting data reveal better organized chelate building activation. Density functional theory (DFT) was created to properly grasp the optimal architecture of the molecules. The chelates are softer than H₂Erx-en, with estimates varying between 95.23 eV to 400.00 eV, compared to 31.47 eV for H₂Erx-en. The disc diffusion technique was utilized to assess H₂Erx-en and their chelates in an antimicrobial assay against various food and phytopathogens. The zirconium(IV) chelate has the most potent antibacterial action and is particularly efficient against Salmonella typhi. Full article

In this research work the outcomes of a hybrid experimental campaign are analyzed, in order to evaluate the influence of aftershock events on the frictional response of sliding-based isolation devices for buildings. To achieve this, a hybrid testing framework was accordingly defined, by considering a numerical substructure, in terms of a simplified analytical model of a case study structure, and a physical substructure, as a full-scale Curved Surface Slider device, tested within the Bearing Tester System of the EUCENTRE Foundation Laboratory in Pavia (Italy). The tested isolator was equipped with a special sliding material, made up of a Poly-Tetra-Fluoro-Ethylene-based compound (PTFE), filled with carbon fibers and with a solid lubrication. The hybrid tests were performed, in terms of earthquake simulations, and the response of the base-isolated structural system was computed, by applying single-events, rather than aftershock chains. Results lead to a better understanding of the behavior of sliding-based seismic isolation systems, characterized by medium-to-high tribological properties, in terms of peak and residual displacements for both the single-event and the mean responses. Specifically, this work provides hybrid experimental evidence of the influence of an initial displacement offset on the overall behavior of the considered structural system. Full article

High-power and lightweight photovoltaic (PV) modules are suitable for building-integrated photovoltaic (BIPV) systems. Due to the characteristics of the installation sites, the BIPV solar modules are limited by weight and installation area. In this study, we fabricated glass-free and shingled-type PV modules with an area of 1040 mm × 965 mm, which provide more conversion power compared to conventional PV modules at the same installed area. Further, we employed an ethylene tetrafluoroethylene sheet instead of a front cover glass and added an Al honeycomb sandwich structure to enhance the mechanical stability of lightweight PV modules. To optimize the conversion power of the PV module, we adjusted the amount of dispensed electrically conductive adhesives between the solar cells. Finally, we achieved a conversion power of 195.84 W at an area of 1.004 m², and we performed standard reliability tests using a PV module that weighed only 9 kg/m². Full article

Fluorine resin membranes with excellent chemical resistance have great potential for the application of high-performance chemical protective clothing. However, it is difficult to integrate fluorine resins into other materials such as fabrics due to their lower surface energy and poor bondability, making the fabrication of composite fabrics and the further seal splicing challenging. In this study, atmospheric pressure dielectric barrier discharge (DBD) plasma in helium (He) and helium/acrylic acid (He/AA) mixture atmospheres were used to modify two kinds of fluorine resins, ethylene tetrafluoroethylene (ETFE) and polytetrafluoroethylene (PTFE) membrane. The surface chemical properties, physical morphology, hydrophilicity and adhesion strength of the fluororesin membranes before and after plasma treatments were systematically analyzed. The results showed that the plasma treatment can modify the membrane surface at the nanoscale level without damaging the main body of the membrane. The hydrophilicity of the plasma-treated membrane was improved with the water contact angle decreasing from 95.83° to 49.9° for the ETFE membrane and from 109.9° to 67.8° for the PTFE membrane, respectively. The He plasma creates active sites on the membrane surface as well as etching the membrane surface, increasing the surface roughness. The He/AA plasma treatment introduces two types of polyacrylic acid (PAA)—deposited polyacrylic acid (d-PAA) and grafted polyacrylic acid (g-PAA)—on the membrane surface. Even after ultrasonic washing with acetone, g-PAA still existed stably and, as a result, improved the polarity and adhesion strength of fluororesin membranes. This work provides useful insights into the modification mechanism of DBD plasma on fluorine resins, with implications for developing effective strategies of integrating fluorine resin membrane to chemical protective clothing fabrics. Full article

In recent years, fluoropolymers have found numerous applications in the architectural field because of their combination of mechanical-chemical resistance and high transparency. In the present work, commercial fluorinated polymers, such as perfluoro alkoxy (PFA) and ethylene tetrafluoroethylene copolymer (ETFE), have been evaluated for use as protective and transparent layers on monumental and archaeological sites (to preserve mosaics or frescoes) during the phases of restoration or maintenance outdoors. Considering this specific application, the present study was developed by evaluating the evolution of the mechanical (tensile, tear propagation resistance, and low-velocity impact tests) and chemical (FTIR and DSC analysis) properties of the films after accelerated UV aging. The results that were obtained demonstrated the high resistance capacity of the ETFE, which exhibits considerably higher elastic modulus and critical tear energy values than PFA films (1075.38 MPa and 131.70 N/mm for ETFE; 625.48 MPa and 59.06 N/mm for PFA). After aging, the samples exhibited only a slight reduction of about 5% in the elastic modulus for both polymers and 10% in the critical tear energy values for PFA. Furthermore, the differences in impact resistance after aging were limited for both polymers; however, the ETFE film showed higher peak force than the PFA films (82.95 N and 42.22 N, respectively). The results obtained demonstrated the high resistance capacity of ETFE films, making them the most suitable candidate for the considered application. Full article

Compared to their predecessors, the next generations of aircrafts will be more electrified, require more electrical power and operate at higher voltage levels to meet strict weight and volume constraints. The combined effect of low-pressure environments, increased voltage levels and compact designs intensifies the risks of premature insulation degradation due to electrical discharge activity. This paper studies the resistance to surface discharges of PTFE (polytetrafluoroethylene) and ETFE (ethylene tetrafluoroethylene), two insulation materials widely used in today’s aircraft wiring systems due to their outstanding properties, such as a wide temperature operation range and a high dielectric strength. The study is carried out in a low-pressure chamber, which was pressurized within the pressure range of 10–100 kPa that includes most aircraft applications. There is a compelling need for experimental data to assess the resistance of insulation materials to surface discharges at a very early stage as a function of the environmental pressure. Data on resistance to surface discharges in low-pressure environments for aeronautical applications are lacking, while most standards for insulation systems are based on tests under standard pressure conditions. The results provided in this work can be useful to design wiring systems for future more electric aircrafts, as well as to design fault detection systems for an early detection and identification of faults related to surface discharges. Therefore, the data and analysis included in this paper could be of great interest to design and develop insulation systems for wiring systems and standard assessment methods, as well as to design fault detection strategies for the early detection and identification of surface discharges for future generations of more electric aircrafts. Full article