Fluorine Resin Research Articles

Light-Field Optimization of Deep-Ultraviolet LED Modules for Efficient Microbial Inactivation

Public awareness of preventing pathogenic microorganisms has significantly increased. Among numerous microbial prevention methods, the deep-ultraviolet (DUV) disinfection technology has received wide attention by using the nitride-based light-emitting diode (LED). However, the light extraction efficiency of DUV LEDs and the utilization rate of emitted DUV light are relatively low at the current stage. In this study, a light distribution design (referred to as the reflective system) was explored to enhance the utilization of emitted DUV from LEDs, leading to successful and efficient surface and air disinfection. Optical power measurements and microbial inactivation tests demonstrated an approximately 79% improvement in average radiation power density achieved by the reflective system when measured at a 5 cm distance from the irradiation surface. Moreover, a statistically significant enhancement in local surface disinfection was observed with low electric power consumption. The reflective system was integrated into an air purifier and underwent air disinfection testing, effectively disinfecting a 3 m3 space within ten minutes. Additionally, a fluorine resin film at the nanolevel was developed to protect the light module from oxidation, validated through a 1200 h accelerated aging test under humid conditions. This research offers valuable guidance for efficient and energy-saving DUV disinfection applications.

High‐Power AlGaN‐Based Ultrathin Tunneling Junction Deep Ultraviolet Light‐Emitting Diodes

AbstractTunnel junctions (TJs) offer a unique approach to utilizing nonequilibrium tunneling injection of holes and have demonstrated potential applications in ultraviolet (UV) emitters. However, high operating voltage caused by the wide bandgap of the III‐nitrides has impeded the further promotion of TJ. Here, 275 nm n+‐Al0.45Ga0.55N/p+‐Al0.5Ga0.5N ultrathin tunnel junction (UTJ) deep‐UV light‐emitting diodes (LEDs) are developed for minimizing the electrical losses and achieve, to the current knowledge, the lowest operating voltage (5.7 V) at 300 mA reported to date. This study discovers that Mg‐Si co‐doping occurs in the n+‐Al0.45Ga0.55N layer during the growth of n+‐Al0.45Ga0.55N/p+‐Al0.5Ga0.5N UTJ due to the memory and diffusion effect of Mg, which leads to the formation of Ohmic contact between high‐work‐function Ni/Au and Mg‐Si co‐doped n+‐ Al0.45Ga0.55N layer in UTJ. The Zener diode, fluorine resin, and optimally designed glass lens are incorporated into the chip encapsulation to enhance the reliability and optical performance of the device. Furthermore, a high‐efficiency sterilization deep‐UV light source is developed integrated with 120 UTJ deep‐UV LED chips. Complete surface inactivation at a long irradiation distance (20 cm) is achieved within only seconds using the high‐power sterilization deep‐UV light source. These results indicate that UTJ is promising in developing deep UV LEDs and their integrated light sources.

Influence of Thin Fluorine Resin Film on DUV LED Packaging Devices

Amorphous fluorine resin is a promising material that can be used for the encapsulation of deep-ultraviolet light-emitting diodes (DUV LEDs) to promote the light output, due to its light characteristics which mean it shows no absorption in the DUV wavelength region. However, obvious decay and high cost are the problems faced by fluorine resin. In this study, thin-fluorine-resin-film-packaged DUV LEDs were fabricated by the drip-coating method and the characteristics were tested. The results show that the light output power increased from 4.95 mW to 5.44 mW at 40 mA, and the cost of fluorine resin can be reduced to ~10%. In addition, no degradation during the aging was observed. However, when the light output power reached 12 mW or higher, >10% decay was observed after aging for 1000 h. In conclusion, thin-fluorine-resin-film-packaged DUV LEDs can achieve 10% light output power enhancement by using less fluorine resin material, and the material is more applicable to low-power DUV LEDs.

Theoretical Prediction on Properties of 3,4-Bisnitrofurazanfuroxan (DNTF) Crystal and its Polymer Bonded Explosives (PBXs) Through Molecular Dynamics (MD) Simulation

3,4-Bisnitrofurazanfuroxan (DNTF) is a typical high energy density compound (HEDC), it has high crystal density and detonation parameters, but also high mechanical sensitivity. To decrease its mechanical sensitivity, the DNTF based polymer bonded explosives (PBXs) was designed. The pure DNTF crystal and PBXs models were established. The stability, sensitivity, detonation performance and mechanical properties of DNTF crystal and PBXs models were predicted. Results show that PBXs models containing fluorine rubber (F2311) and fluorine resin (F2314) have higher binding energy, meaning that DNTF/F2311 and DNTF/F2314 is relatively more stable. PBXs models have higher value of cohesive energy density (CED) than pure DNTF crystal, DNTF/F2311 and DNTF/F2314 have the highest value of CED, implying that the sensitivity of PBXs is effectively decreased, DNTF/F2311 and DNTF/F2314 is more insensitive. PBXs have lower crystal density and detonation parameters than DNTF, the energy density is declined, DNTF/F2314 has higher energetic performance than other PBXs. Compared with pure DNTF crystal, engineering moduli (tensile modulus, shear modulus, bulk modulus) of PBXs models are obviously decreased, but Cauchy pressure is increased, implying that the mechanical properties of PBXs is superior to pure DNTF component, the PBXs containing F2311 or F2314 have more preferable mechanical properties. Consequently, DNTF/F2311 and DNTF/F2314 have the best comprehensive properties and is more attractive among the designed PBXs, indicating that F2311 and F2314 are more advantageous and promising in ameliorating properties of DNTF. The properties of DNTF crystal and PBXs models were predicted through molecular dynamics (MD) method under Materials Studio 7.0 package. The MD simulation was performed with isothermal-constant volume (NVT) ensemble, and the force field was chosen as COMPASS force field. The temperature was set as 295K, the time step was 1fs and the total MD simulation time was 2ns.

Preparation of PLA-based SMS nonwoven composites and its applications in protective apparel

The global COVID-19 pandemic has triggered a huge demand for the protective nonwovens. However, the main raw material of nonwovens comes from petroleum, and the massive consumption of petroleum-based polymers brings great pressure to ecosystem. Therefore, it is significant to develop biodegradable protective barrier products. In this work, a polylactic-based composite (a tri-layer nonwovens composed of spunbond, meltblown and spunbond, SMS) was prepared and applied for protective apparel. The surface morphology and chemical changes of the fibers were characterized and analyzed by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR) and energy dispersive spectroscopy (EDS). The liquid contact angle and permeability, breathability and moisture permeability, frictional charge and mechanical strength of the samples were evaluated and compared. The samples degradability was also recorded. The results demonstrate that the optimum formula for anti-fouling treatment on SMS is F-30. The treated fabric possesses superior liquid repellency and anti-permeability, with contact angles of water and alcohol at 128° and 115° respectively, while the alcohol repellent grade reaches level 7. The treated sample has less strength loss but exhibits favorable breathability, moisture permeability and anti-static properties, which can meet the requirements of protective apparels. After fluorine resin coating, the composite still provide excellent degradation performance, and the weight loss rate reaches more than 80% after 10 days water degradation. These results provide new insights for the application of PLA-based SMS in biodegradable protective apparel.

Theoretical research on performances of CL-20/HMX cocrystal explosive and its based polymer bonded explosives (PBXs) by molecular dynamics method.

In this article, the CL-20/HMX cocrystal model was established and its based polymer bonded explosives (PBXs) were designed. The static performances, including mechanical properties, stability and detonation performance of CL-20/HMX cocrystal model and PBXs models, were predicted by molecular dynamics (MD) method. The mechanical parameters, binding energy, and detonation parameters of PBXs models were calculated and compared with that of pure CL-20/HMX cocrystal model. The influence of polymer binders on performances of CL-20/HMX cocrystal explosive was evaluated. Results show that the polymer binders make the engineering moduli (tensile modulus, shear modulus, and bulk modulus) of PBXs declined and Cauchy pressure increased, meaning that the polymer binder can obviously improve mechanical properties of CL-20/HMX cocrystal explosive, and the PBXs model with fluorine rubber (F2311) has the best mechanical properties. In different PBXs models, the binding energy between CL-20, HMX molecules and F2311 is higher than other polymer binders, indicating that the CL-20/HMX/F2311 model is more stable. The PBXs models have lower value of crystal density and detonation parameters compared with pure CL-20/HMX cocrystal and the energetic performance of PBXs is weakened. The PBXs model with fluorine resin (F2314) has the highest energetic performance and it is higher than pure HMX. Therefore, the CL-20/HMX/F2311 and CL-20/HMX/F2314 models have more favorable comprehensive properties, proving that F2311 and F2314 are more preferable and promising to design CL-20/HMX cocrystal based PBXs.

Fabrication of laminated composite filter with nonwoven fabrics for oil/water separation

Various materials have been prepared and applied for the oil-water mixture separation, but there are some problems such as high cost, complicated formulation process and inferior durability. Nonwoven fabrics are widely used in industrial fields because of their low production cost and high economic benefit. In this study, a sandwich-structure filter was prepared for oil/water separation based on laminated nonwovens. Spunbond-meltblown-spunbond (SMS) nonwoven treated with silica and fluorine resin was selected for the hydrophobic top layer. The spunlaced viscose (VS) impregnated with citrate was used for the hygroscopic core layer while spunbond polypropylene (PP) prepared for the bottom substrate. These three layers were reinforced on an ultrasonic-bonding machine and tested for oil-water separation. Surface morphology and chemical group changes of treated fiber were recorded by scanning electron microscope (SEM), atomic force microscope (AFM), energy dispersive spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR). The effect of surface hydrophobicity and core hydrophilicity on separation efficiency was analyzed. The durability after recycles was evaluated and discussed. The possible separation mechanism was proposed. The results demonstrated that coating and spraying methods achieved uniform distribution of silica and fluorine resin onto the fiber surface. The suitable conditions for the preparation of composite filter were obtained as follows: the surface SMS layer was coated with silica, then sprayed with fluorine resin for a 6.0%weight gain to get a hydrophobic layer. The core layer viscose fiber impregnated with 3.0% citrate to enhance its hygroscopicity. The three layers were laminated and reinforced for the composite filter. Improving the hydrophobicity of top layer and the hydrophilicity of core layer both contributed to the enhance of separation efficiency and stability. The pore size of composite filter was mainly in the range of 9-11μm with a 35% distribution. After 15 times recycles, the water recovery ratio remains over 95% while water contact angle decreased from 150° to 135°. After layers laminated and bonding, the hydrophobic surface trapped oil and water in the mixture, hygroscopicity layer enabled a connection with the water in mixture through SMS layer and formed a capillary water channel. The water transferred to the sublayer by gravity and capillary action to actualize oil-water separation. These results provided new insights for the application of nonwoven fabrics on oil-water separation.

Surface Modification of ETFE Membrane and PTFE Membrane by Atmospheric DBD Plasma.

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.

A Facile Method to Prepare Superhydrophobic Coatings for Various Substrates

In this study, the superhydrophobic composite coatings for self-cleaning were fabricated by mixing fluorine resin and two kinds of nanoparticles of carbon nanotubes (CNTs) and SiO2. When the mass ratio of CNTs to SiO2 is 2:3 and the added amount of nanoparticles is 75 wt. %, the superhydrophobic composite coatings with a water contact angle of 156.8° show the best self-cleaning property and 3.6° of contact angle hysteresis. Furthermore, the superhydrophobic composite coatings demonstrate good properties such as chemical resistance, thermal stability, and mechanical stability. The superhydrophobic composite coatings could be used for oil/water separation and could be applied to various substrate surfaces such as glass plates, cloth, board, steel plate, PVC plate, and so on. The superhydrophobic composite coatings show practical value in many fields because of their low cost and large area preparation.

Investigation of Contaminants in Single Wafer Wet Cleaning Using Isopropyl Alcohol

Technological control over ultra-trace level contaminants is important for semiconductor development. Despite technological developments, defects remain in the single wafer wet cleaning process. In this paper, the source of the contamination is explained via trace analytical methods. Fluorine resin materials of polytetrafluoroethylene (PTFE) and ethylene tetrafluoroethylene (ETFE) are commonly used in semiconductor equipment. Isopropyl alcohol (IPA) oxidation reactions occur at high temperature below the boiling point due to impurities. IPA changed to different alcohol forms from gas chromatography (GCMS) analysis. The oxygen concentration in the X-ray photoelectron spectroscopy (XPS) results increased and formed new bonds in IPA with fluorine resin. These reactions confirmed that cations were a catalyst from the time-of-flight secondary ion mass spectrometry (TOF-SIMS) results. Representative ions were Fe+, K+, and Na+ with different concentrations for each material.

Novel Nano-Filled Coatings for the Protection of Built Heritage Stone Surfaces

An experimental nano-filled coating, based on a fluorine resin containing SiO2 nano-particles, was applied on calcareous stones, representative of materials used in buildings and monuments of the Mediterranean basin; for comparison purposes, two commercial products were applied on the same substrates. The efficacy of the protective treatments was assessed by analyzing different characteristics of the three experimental/commercial products, i.e., color changes and permeability to water vapor to evaluate the treatments’ harmlessness; capillary water absorption and water stone contact angle to evaluate the protection against water ingress; oleophobicity of the treated surfaces and the behavior under staining by acrylic blue-colored spray paint and felt-tip marker to verify the anti-graffiti action. Finally, the properties of the treated stone surfaces were analyzed also after the application of pancreatin, used to simulate bird excreta (guano). The protective coatings were found to promote graffiti removal, reducing also the detrimental effects due to simulated guano. The experimental nano-filled product, in addition, was able to provide outstanding performance but using smaller amounts of product in comparison to commercial systems.

Plasma-induced Surface Modification of Fluorine Resin Films for Direct Plating

Plasma-induced Surface Modification of Fluorine Resin Films for Direct Plating

Applicability of a 100-mL Polyethylene Vial for Low-Level Tritium Measurement Using a Low-Background Liquid Scintillation Counter

For low-level tritium measurements using a liquid scintillation counter, scintillation vial selection is important. The applicability of polyethylene (PE) vials was studied. Three types of vials were tested: (1) 100-mL perfluoroalkoxy alkane (PFA) fluorine resin vials, (2) 100-mL PE vials, and (3) 145-mL PE vials. Ultima Gold LLT was the reference liquid scintillator in this study. The background counts for these vials were found to be 2.5 counts per minute. Tritiated water of 1.5 Bq‧mL−1 was employed as an internal standard to determine the counting efficiency. The counting efficiencies for the 100-mL PFA, 100-mL PE, and 145-mL PE vials were estimated to be 17%, 16%, and 13%, respectively. The lower limits of detection of these vials for a counting time of 100 min were 1.45 Bq‧L−1 for 100-mL PFA vials, 1.54 Bq‧L−1 for 100-mL PE vials, and 1.47 Bq‧L−1 for 145-mL PE vials. Thus, these vials demonstrate similar performances for tritium measurements.

Effect of Different Color Paste on Properties of Fluorine Resin/Aluminum Infrared Low Emissivity Coating

The effect of the four kinds of red, dark yellow, purple, and black pastes on the properties of fluorine resin/aluminum low emissivity coating was studied. The infrared emissivity coatings with red and black pastes were higher than the coatings with dark yellow and purple pastes. The hardness of the coatings with red, dark yellow, and purple color pastes was 6H, and that with black pastes was 6B. The adhesion and impact resistance of dark yellow coating was better, followed by red and purple, and the adhesion and impact resistance of black coating was the worst. Electrochemical polarization curves indicated that fluorine resin coatings with purple paste had better corrosion resistance. After the salt water resistance test, there was no obvious loss of light in the coatings with the four kinds of color pastes. The purple paste coating had no obvious loss of light and less bubble, suggesting that the fluorine resin/aluminum low emissivity coating with purple paste had better performance. The results of this study provide a new prospect for the application of infrared low emissivity coating in infrared stealth and compatibility with visible light.

Anti-Graffiti Behavior of Oleo/Hydrophobic Nano-Filled Coatings Applied on Natural Stone Materials

In recent years, graffiti writings are increasingly regarded as a form of art. However, their presence on historic building remains a vandalism and different strategies have been developed to clean or, preferably, protect the surfaces. In this study, an experimental nano-filled coating, based on fluorine resin containing SiO2 nano-particles, and two commercial products have been applied on compact and porous calcareous stones, representative of building materials used in the Mediterranean basin, and their anti-graffiti ability has been analyzed. All the tested experimental and commercial coatings exhibited high hydrophobicity and oleophobicity, thus meeting one of the basic requirements for anti-graffiti systems. The effects of staining by acrylic blu-colored spray paint and felt-tip marker were, then, assessed; the properties of the treated stone surfaces after cleaning by acetone were also investigated. Visual observations, contact angle measurements and color evaluations were performed to this aim. It was found that the protective coatings facilitated the spray paint removal; however high oleophobicity or paint repellence did not guarantee a complete cleaning. The stain from the felt-tip marker was confirmed to be extremely difficult to remove. The cleaning with a neat unconfined solvent promoted the movement of the applied polymers (and likely of the paint, as well) in the porous structure of the stone substrate.

Effect of Black Paste on the Property of Fluorine Resin/Aluminum Infrared Coating

A fluorine resin/aluminum infrared coating was prepared with aluminum using black paste as filler and fluorine resin as binder. The effect of the black paste content on the performance of gloss, color difference, infrared emissivity, hardness, adhesion, impact resistance, roughness, optical testing, and corrosion resistance of the fluorine resin/aluminum infrared coating were examined. When the content of black paste was increased from 1.0% to 9.0%, the gloss of the coating surface decreased; the ΔE* value of the coating decreased; the infrared emissivity of the coating surface increased gradually; the hardness of the coating was 6H; the adhesion grade of the coating was 0; the infrared absorption peak increased gradually. When the content of black paste was 0%–3.0%, the impact resistance was more than 50 kg∙cm, and the impact resistance was higher. When the content of black paste was 0%–5.0%, the surface roughness of the coating was relatively low. When the content of black paste was 1.0%, the corrosion resistance of the coating was the best. The results showed that when the content of black paste was 1.0%, the performance of the whole fluorine resin coating was the best. Through the preparation and characterization of fluorine resin infrared low-emissivity coatings, the possibility of applying fluorine resin to infrared low-emissivity anticorrosive coatings was discussed, which laid a foundation for the subsequent engineering application of coatings.

Oleo/Hydrophobic Coatings Containing Nano-Particles for the Protection of Stone Materials Having Different Porosity

Conservation strategies to limit the degradation of stone materials are being constantly developed. To this aim, new materials are designed to confer hydrophobic properties and anti-graffiti protection to the treated surfaces. Hybrid nanocomposites, based on inorganic nano-particles added to an organic matrix, have been recently proposed for treatments of stone surfaces, obtaining promising and innovative properties. In the present paper, an experimental product based on fluorine resin containing SiO2 nano-particles, a commercial fluorine-based product and a silicon-based material were applied as protective coatings on two calcareous stones (compact and porous) widely employed in the Mediterranean region. All the studied products are expected to provide both water and anti-graffiti protection to both stones’ surfaces. The rheological characterization of the liquid products, changes in color of the surfaces, and variations in water vapor permeability allowed the compatibility of the protective systems applied to stones to be evaluated. Water–stone contact angle measurements and water absorption by capillarity were used to control the action against water ingress. The oleophobicity was assessed by measuring the oil–stone contact angle. The experimental nano-filled product proved to be a suitable hydrophobic coating for compact and porous stones; furthermore, it provides high oleophobicity to the treated surfaces, as required for anti-graffiti systems.

Study on the Main‐Chain Structure of Amorphous Fluorine Resins for Encapsulating AlGaN‐Based DUV‐LEDs

The main chain structure of optically isotropic amorphous fluorine resin for encapsulating AlGaN‐based deep‐ultraviolet LEDs (λ < 300 nm) is studied. One type of amorphous fluorine resin has a five‐membered ring with a single oxygen atom and the other has that one with two oxygen atoms. Reliability testing is performed using AlGaN‐based LEDs of 262 and 289 nm. For the resin with two oxygen atoms in the ring, visible damage to the electrode and significantly increased leakage current are considered to been caused by the photolysis of the ring induced by irradiation with deep‐ultraviolet light. In contrast, electrode damage and increased leakage are not observed in the case of the resin with the single‐oxygen ring.

Electrical Resistivity of Natural Graphite-Fluorine Resin Composite for Bipolar Plates of Phosphoric Acid Fuel Cell(PAFC) Depending on Graphite Particle Size

A composite material was prepared for the bipolar plates of phosphoric acid fuel cells(PAFC) by hot pressing a flake type natural graphite powder as a filler material and a fluorine resin as a binder. Average particle sizes of the powders were 610.3, 401.6, 99.5, and 37.7 μm. The density of the composite increased from 2.25 to 2.72 g/cm3 as the graphite size increased from 37.7 to 610.3 μm. The anisotropy ratio of the composite increased from 1.8 to 490.9 as the graphite size increased. The flexural strength of the composite decreased from 15.60 to 8.94MPa as the graphite size increased. The porosity and the resistivity of the composite showed the same tendencies, and decreased as the graphite size increased. The lowest resistivity and porosity of the composite were 1.99 × 10−3 Ωcm and 2.02 %, respectively, when the graphite size was 401.6 μm. The flexural strength of the composite was 10.3MPa when the graphite size was 401.6 μm. The lowest resistance to electron mobility was well correlated with the composite with lowest porosity. It was possible the flaky large graphite particles survive after the hot pressing process.

Molecular dynamics simulations for CL-20/TNT co-crystal based polymer-bonded explosives

Molecular dynamics (MD) simulations were carried out to study the polymer-bonded explosives (PBXs) where the explosive base was the well-known high energy co-crystal compound, 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexazaisowurtzitane/2,4,6-trinitrotoluene (CL-20/TNT), and the polymer binders were fluorine rubber (F[Formula: see text], fluorine resin (F[Formula: see text], polyvinyl acetate (PVAc) and polystyrene (PS), respectively. The binding energies, pair correlation functions (PCFs) and mechanical properties of the PBXs were reported. According to our theoretical results of binding energies, the compatibility of the PBXs is predicted to be in the following order: CL-20/TNT/PVAc[Formula: see text] CL-20/TNT/F[Formula: see text] [Formula: see text] CL-20/TNT/PS [Formula: see text] CL-20/TNT/F[Formula: see text]. The binding energies of the PBXs on three crystalline surfaces, (100), (001), (010), of the CL-20/TNT co-crystal were also compared: CL-20/TNT(100)[Formula: see text]CL-20/TNT(001)[Formula: see text]CL-20/TNT(010) for F[Formula: see text], F[Formula: see text], and PS; CL-20/TNT(001)[Formula: see text]CL-20/TNT(100)[Formula: see text]CL-20/TNT(010) for PVAc. The PCF analysis reveals that there exist H-bonds between H and O, F, and N atoms on all three interfaces and among all H-bonds, N H-bond has the fewest number. For the CL-20/TNT co-crystal, the moduli can be reduced by adding a small amount of the polymer binders but the ductility can be prolonged only by F[Formula: see text] and F[Formula: see text].