Polytetrafluoroethylene Material Research Articles

Investigation of tribological performance of hydrothermal carbon by pin-on-disc test and warm deep drawing process

In this study, the synthesis of hydrothermal carbon (HTC) lubricant and its usability as a lubricant under hot industrial conditions were investigated. In this context, the characterization of HTC produced from organic sources at low cost and in a short time was performed, and its tribological performance was analysed in detail. HTC produced by the hydrothermal carbonization method was characterized through SEM images and EDS analysis. To determine the effect of HTC on friction at different temperatures, HTC was subjected to a pin-on-disc wear test with AA5754 material. The effect of various lubricants, temperatures, blank holder pressure, and forming speed parameters on the forming force for the analysis of the tribological effect of HTC on deep drawing processes were statistically analysed. The performance of HTC was compared with Teflon, fullerenes, graphene, and carbon nanotube (CNT) materials. According to the results obtained from wear tests, the lowest friction coefficient value was achieved in the presence of fullerenes as the lubricant, and as the temperature increased, the friction coefficient decreased. It was observed that HTC exhibited lower performance in the wear test compared to fullerenes due to oxidation. When the effect of deep drawing parameters on the forming force was analysed, it was concluded that the most effective parameters were temperature (72.32%) and lubricant (20.89%). According to the S/N analysis results, the minimum forming force was obtained under the conditions of solid Teflon lubricant, 250 °C temperature, 15-bar blank holder pressure, and 2 mm/s forming speed. The tribological performance difference between HTC and Teflon is at the 1% level. The results demonstrate the potential industrial usability of HTC as a lubricant.

Towards sustainable, direct printed, organic transistors with biocompatible copolymer gate dielectrics

Towards sustainable, direct printed, organic transistors with biocompatible copolymer gate dielectrics

THE MICROSTRIP ARRAY ANTENNA WITH REFLECTOR at 1.4 AND 2.4 GHz for RADARS APPLICATIONS

This study presents an E-shaped array microstrip antenna design with a reflector, which has a high gain for short-range radar studies. E-shaped dipoles at the top of the substrate are brought into contact with an irregular microstrip line, which is the bottom of FR-4 substrate. The antenna feed is excited using a coaxial cable. The substrate material and the chrome reflector are attached to each other with Teflon material. The proposed antenna provides 7.85 and 9.62 dBi gains at resonance frequencies of 1.4 and 2.4 GHz, respectively. This antenna also has an F/B ratio of over 15 dB and an HPBW (half power beam width) value able to be used for short-ranges.

Design of High-Gain Antenna Arrays for Terahertz Applications.

A terahertz band (0.1-10 THz) has the characteristics of rich spectrum resources, high transmission speed, strong penetration, and clear directionality. However, the terahertz signal will suffer serious attenuation and absorption during transmission. Therefore, a terahertz antenna with high gain, high efficiency, and wide bandwidth is an indispensable key component of terahertz wireless systems and has become a research hotspot in the field of antennas. In this paper, a high-gain broadband antenna is presented for terahertz applications. The antenna is a three-layer structure, fed by a grounded coplanar waveguide (GCPW), using polytetrafluoroethylene (PTFE) material as the dielectric substrate, and the metal through-hole of the dielectric substrate forms a substrate-integrated waveguide (SIW) structure. The metal fence structure is introduced to reduce the coupling effect between the radiation patches and increase the radiation bandwidth and gain. The center frequency is 0.6366 THz, the operating bandwidth is 0.61-0.68 THz, the minimum value of the voltage standing wave ratio (VSWR) is 1.00158, and the peak gain is 13.14 dBi. In addition, the performance of the designed antenna with a different isolation structure, the length of the connection line, the height of the substrate, the radius of the through-hole, and the thickness of the patch is also studied.

Preparation and application of superhydrophobic polytetrafluoroethylene materials and micro/nanoindentation

A method for preparing superhydrophobic polytetrafluoroethylene materials by micro- and nanoimprinting is discussed. Surfaces with superhydrophobic properties were prepared by designing and imprinting micro- and nano-structures on polytetrafluoroethylene materials. The experiments on weather resistance and durability revealed that the microstructure of screens of different mesh sizes was processed onto the surface of PTFE material by micro-nano thermal imprinting to make it hydrophobic and oleophobic, and retained the original excellent properties of corrosion resistance and low surface attachment, etc. The material processed by the new method has a wide range of application prospects in various fields.

Introducing Leather in Wearable Triboelectric Generators

Leather is a well-known material with a wide range of applications in clothing, footwear, protection, accessories and furnishing. Further on it is reported in only a few triboelectric series tables, as a material which has an intensive tendency to become positive. In the hereby study, its triboelectric potentials are examined to be used as part of a triboelectric generator which would be part of clothing. Natural leather from cows and sheep was used. Samples of 25 cm2 area were cut and examined together with Polytetrafluoroethylene (PTFE) material, using a prototype measuring triboelectric generator device under a force of 0.5 N. The highest Vpp values were given by the front (grain) side of cow and sheep thin samples, reaching a mean Vpp of 1293 and 1233 mV respectively. In all the tests, the front side of the samples performed better than their back (flesh) as a triboelectric surface. Additionally, the thin samples performed better than the thick ones and the less stiff samples performed better than the stiff ones. The outcoming voltages seem promising in comparison to other ordinary natural materials previously studied. The results point to the potential of leather usage in wearable triboelectric generators.

PatchRLNet: A Framework Combining a Vision Transformer and Reinforcement Learning for The Separation of a PTFE Emulsion and Paraffin

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.

A 9.73 GHz wide-band off-body patch antenna for biomedical applications

<span>The primary goal of this study is to design a simple antenna that has a wide bandwidth and low return loss for biomedical applications. The paper shows the recommended antenna’s three-stage modeling, with the goal of assessing every important parameter while a Teflon or polytetrafluoroethylene (PTFE) polymer substrate is used. In order to better comprehend, a comparison with prior studies employing teflon and similar substrate materials is conducted for the proposed patch antenna. The analysis includes the phantom model, evaluating performance criteria such as specific absorption rate (SAR), return loss, bandwidth, and gain values relevant to biomedical applications. The antenna works at two different frequencies: 9.73 and 9.39 GHz, one in free space and another in a skin-cotton layer. The bandwidth of the antenna is 4.067 GHz in free space at the resonance frequency of 9.73 GHz, where the return loss is -62.18 dB. The performance of the proposed antenna in the field of biomedical applications, its underlying reasons, and its impacts are discussed in detail in this study.</span>

Efficient High Gain Elliptically Polarized Phased MIMO Antenna

A phased MIMO antenna with a coaxial feed is designed to operate in the electromagnetic spectrum with the frequency range of 8 GHz to 12 GHz, which resonates at 9 GHz, is used in military and satellite communication. The ability of phased MIMO antennas to change the form and orientation of the radiation pattern without constantly moving the antenna is unique. The proposed approach can also improve radiation efficiency by maximizing array unit size. To validate the proposed method, an elliptical polarization phased antenna has been constructed as a planar array. A 2 to 2 planar dual polarized MIMO antenna is intended to improve the efficiency. The obtained return loss for 2x2 planar MIMO is -19.34 dB. The proposed 2x2 MIMO antenna is projected on a teflon material with dielectric constant of 2.25 and the thickness of the substrate is 7mm. The efficiency for two port MIMO antenna is 97.7%.

Lenslet-array-based snapshot hyperspectral imaging polarimeter using opposite spectral modulation

We present a lenslet-array-based snapshot hyperspectral imaging polarimeter (LSHIP) that integrates spectral polarization modulation (SPM) into integral field imaging spectrometry. The LSHIP can simultaneously acquire three-dimensional spatial and spectral data-cubes for linear Stokes parameters in a single snapshot without any moving parts. The dual-scan technique is achieved through a custom-fabricated Wollaston prism that can simultaneously generate pairs of micro-spectra with opposite spectral modulations, maintaining the system's intrinsic spectral resolution during intensity spectrum reconstruction. We describe the principle and experimental setup of the LSHIP, as well as the system calibration and validation using measurements of polarized color blocks and a sphere made of polytetrafluoroethylene material. The prototype can cover the spectral range of 450–650 nm with 157 sample points, capturing approximately 3700 SPM micro-spectra spatially distributed on the detector in a single integration time. These results demonstrate the potential of the LSHIP for various applications, including remote sensing and biomedical diagnosis.

Tailoring the Hydrophobic Interface of Core-Shell HKUST-1@Cu2O Nanocomposites for Efficiently Selective CO2 Electroreduction.

The electrochemical reduction of carbon dioxide (CO2) to ethylene creates a carbon-neutral approach to converting carbon dioxide into intermittent renewable electricity. Exploring efficient electrocatalysts with potentially high ethylene selectivity is extremely desirable, but still challenging. In this report, a laboratory-designed catalyst HKUST-1@Cu2O/PTFE-1 is prepared, in which the high specific surface area of the composites with improved CO2 adsorption and the abundance of active sites contribute to the increased electrocatalytic activity. Furthermore, the hydrophobic interface constructed by the hydrophobic material polytetrafluoroethylene (PTFE) effectively inhibits the occurrence of hydrogen evolution reactions, providing a significant improvement in the efficiency of CO2 electroreduction. The distinctive structures result in the remarkable hydrocarbon fuels generation with high Faraday efficiency (FE) of 67.41%, particularly for ethylene with FE of 46.08% (-1.0V vs RHE). The superior performance of the catalyst is verified by DFT calculation with lower Gibbs free energy of the intermediate interactions with improved proton migration and selectivity to emerge the polycarbon（C2+） product. In this work, a promising and effective strategy is presented to configure MOF-based materials with tailored hydrophobic interface, high adsorption selectivity and more exposed active sites for enhancing the efficiency of the electroreduction of CO2 to C2+ products with high added value.

Abstract 11589: Late Complications After Interrupted Aortic Arch Repair

Description of Case: A 38-year-old man with known type B interrupted aortic arch (IAA), bicuspid aortic valve, and a complex surgical history (including IAA repair with an ascending-descending aortic conduit, later conduit graft revision, and left pulmonary artery [LPA] stent) presented after many years of loss to follow-up and was found to have hypertensive urgency. Echocardiogram showed turbulent flow in the proximal descending aorta concerning for arch obstruction. Computed tomography angiography (CTA) (Fig. 1 A–C) showed: narrowed proximal graft anastomosis, dilation of the aortic root and ascending aorta, a large pseudoaneurysm arising from the distal graft anastomosis, and LPA stenosis due to compression from the descending aorta. Following improved hypertension, the patient underwent placement of a left carotid-subclavian bypass graft followed by thoracic endovascular aortic repair (TEVAR) with an endograft positioned across the distal aortic jump graft suture line. CTA one month postoperatively (Fig. 1 D–F) confirmed exclusion of the pseudoaneurysm. Discussion: Type B IAA is considered the most common subtype of IAA among cases diagnosed in infancy, though recent data regarding IAA epidemiology are scarce. IAA is associated with other congenital abnormalities, such as ventricular septal defect (VSD), LV outflow tract abnormalities, and 22q11 deletion syndrome. Additional surgical aortic arch procedures in these patients are not uncommon, perhaps especially among patients who required reintervention for LV outflow tract obstruction. While most studies examining long-term outcomes after IAA repair have not commented specifically on late risk of aneurysm or pseudoaneurysm, such findings have been described in the literature. Additionally, use of polytetrafluoroethylene material in arch repair and arch repair by a method other than direct anastomosis—such as were seen in our patient—have been observed to be risk factors for late reintervention.

Study of Cyclic Plasticity and Creep Ratchet Behavior of PTFE

Due to its superior corrosion resistance and low coefficient of friction, polytetrafluoroethylene (PTFE) is extensively used in the aerospace, machinery, chemical, and pharmaceutical industries. However, PTFE components encounter complex alternating stresses, resulting in ratchet and creep, which will affect the component’s reliability. It is therefore necessary to clarify the PTFE’s resistance to ratchet and creep. In this paper, uniaxial ratchet and tensile creep experiments were conducted at five temperatures on a PTFE dog-bone tensile specimen. At various temperatures and stress levels, the effects of average stress and stress amplitude on the cyclic plastic behavior of PTFE were investigated. It is demonstrated that the ratchet strains and strain rates at 23 °C are greater than those at 50 °C. The reason for this is that the PTFE material exhibits different crystal states at these two temperatures. At temperatures above 50 °C, the ratchet strain and ratchet strain rate increase with temperature. At temperatures above 100 °C, the ratchet strain and ratchet strain rate of PTFE materials increase more rapidly due to the glass transition. By analyzing the creep strain and ratchet strain of specimens subjected to varying levels of average and amplitude stress, it was discovered that the creep strain and ratchet strain caused by the average stress under the same stress increment were greater than those caused by the amplitude stress.

Investigation of the effect of the cut parameter on the machining performance of PTFE cutting

PTFE materials are widely used in the ultra-clean flow control products. However, their mechanical processing characteristics are very different from metal and other non-metallic materials. In this study, the impact of cutting parameters on the machining quality during the cutting-off process of neat polytetrafluoroethylene (PTFE) was investigated using the Taguchi method. The results showed that the turning tool exhibit a regular pattern where the diamond turning tool displaying a larger average cutting force and a higher maximum cutting temperature compared to the cemented carbide turning tool under various cutting conditions. The effects of three cutting parameters on PTFE machining quality were compared. It was found that the extension elongation should be prioritized when selecting cutting parameters in order to ensure stability in the cutting process. The surface morphologies of the workpieces were analyzed for reference in parameter selection and a cutting force model formula was deduced through stress analysis of the treated substrate. This model provides a feasible foundation for optimizing the manufacturing process of fluoroplastics.

Preparation and characterization of complex shaped polytetrafluoroethylene (PTFE) parts based on vat photopolymerization 3D printing

The utilization of vat photopolymerization (VPP) technology presents a novel approach for the production of PTFE parts with intricate geometries. Nevertheless, excessive exposure during photocuring and deformation warpage resulting from the debinding and sintering procedures significantly impact the printing precision of these parts. To achieve high quality printing of complex shaped PTFE parts, this research undertook a systematic investigation of the vat photopolymerization 3D printing process and characterized the final parts. Initially, an assessment was conducted on the rheological properties of photocuring slurries featuring different levels of solid loadings, and the Jacob working curves were established for varying solid loadings and dye concentrations to elucidate the impact of slurry components on photocurable properties. Through thermogravimetric analysis, the optimum debinding temperature for printed green bodies was determined, resulting in the production of PTFE parts devoid of any defects or distortions and the effectiveness of the debinding process was verified by Raman spectroscopy. Then conducted a characterization of the density and mechanical properties of 3D printed PTFE parts, revealing a density reached 99.0% of the conventionally machined PTFE parts, as well as tensile and yield strengths of 22.04 MPa and 12.57 MPa, respectively. Finally, PTFE micro-structural surfaces were constructed via vat photopolymerization 3D printing process, resulting in favorable hydrophobic performance. These findings contribute to a comprehensive understanding of the 3D printing process for PTFE material and offer theoretical guidance for the effective production of complex shaped PTFE parts.

Study on the Reflective Principle and Long-Term Skid Resistance of a Sustainable Hydrophobic Hot-Melt Marking Paint

Road marking is very important for driving safety and reducing the accident rate as a basic component of highway construction. However, traditional road marking paints are prone to be worn after short-term application and have poor durability and reflective performance. To address these problems, the marking paint was modified using the organic polymer material polytetrafluoroethylene to create a durable hydrophobic hot-melt marking paint. The factors affecting the reflective performance of marking lines are analyzed, and artificial accelerated abrasion tests were carried out to analyze the skid resistance and marking retroreflection coefficient of hydrophobic coatings. Results show that the texture of the glass beads and the quality of the coating plays a major role in the reflective performance of the marking line. The friction coefficient value of the modified marking paint is 4.62% higher than that of the traditional hot-melt marking paint. The retroreflection performance of the marking paint with 4% hydrophobic material is 8.45% higher than the initial value of the retroreflection coefficient of the traditional hot-melt marking paints. This sustainable hydrophobic hot-melt marking paint is safer and more durable than traditional pavement marking paints, which may save follow-up maintenance resources and cost from the sustainable aspect.

Enhanced output performance of graphene oxide based triboelectric nanogenerators via plasmon coupling

Graphene Oxide and its derivatives continue to attract the attention of materials scientists in view of their diverse applications. In this paper, we describe the potential of graphene oxide decorated with silver nanoparticles (GO-AgNPs) in energy harvesting, a study inspired by the synergistic effects of surface functionalization of GO with metal nanoparticles. Here, we investigate the triboelectric properties of the composite by constructing the prototype of a free standing nanogenerator with the aid of GO-AgNP based paper and Teflon fabric. Studies using this protype is seen to yield a peak output power of 40 μW for a voltage of 0.2 V, which could be used for the development of sensors. According to the morphological and optical investigations done on GO and GO-AgNPs, the increased output voltage is caused by nanoparticle plasmon coupling on the GO surface.

A review of the development of interventional devices for mitral valve repair with the implantation of artificial chords.

Mitral regurgitation (MR) was the most common heart valve disease. Surgical repair with artificial chordal replacement had become one of the standard treatments for mitral regurgitation. Expanded polytetrafluoroethylene (ePTFE) was currently the most commonly used artificial chordae material due to its unique physicochemical and biocompatible properties. Interventional artificial chordal implantation techniques had emerged as an alternative treatment option for physicians and patients in treating mitral regurgitation. Using either a transapical or a transcatheter approach with interventional devices, a chordal replacement could be performed transcatheter in the beating heart without cardiopulmonary bypass, and the acute effect on the resolution of mitral regurgitation could be monitored in real-time by transesophageal echo imaging during the procedure. Despite the in vitro durability of the expanded polytetrafluoroethylene material, artificial chordal rupture occasionally occurred. In this article, we reviewed the development and therapeutic results of interventional devices for chordal implantation and discuss the possible clinical factors responsible for the rupture of the artificial chordal material.

Structure optimization, optical design and thermal management of UVC LED photoreactor to improve its inactivation efficiency

Compared with the chlorine disinfection, ultraviolet light emitting diode (UV LED) has attracted extensive interest due to its advantages of environmental friendliness, wide inactivation range and easy automation. However, there are still some challenges on how to apply UV LED to water disinfection more effectively by designing and optimizing some parameters. In this manuscript, the optimal numbers, spacing and configuration of UVC LEDs are systematically studied using the thermal and optical software simulation and experiment methods. Then, the influence of the reactor shape and reflective material on inactivation efficiency of the photoreactor was studied in detail. The results show that the appropriate numbers and spacing of UVC LEDs is helpful not only to increase the average irradiance and petri factor of reactor surface but also to keep a low chip junction temperature. The simulation results of three UVC LED configurations indicate the four corners configuration exhibits the highest average irradiance and petri factor value. The introduction of reflective materials can enhance the inactivation performance, and especially the polytetrafluoroethylene (PTFE) material can effectively increase the inactivation efficiency of module by ∼42% because of higher reflectivity and light uniformity. The further inactivation experiments reveal that the designed cylinder reactor covered with PTFE materials has the maximum log inactivation value. The current research results can provide some reliable suggestions for the design and optimization of UVC LED photoreactor to improve its inactivation effect through optical simulation and experimental methods.

UV and IR dual light triggered cellulose-based invisible actuators with high sensitivity

Actuators are widely used in bionic devices and soft robots, among which invisible actuators have some unique applications, including performing secret missions. In this paper, highly visible transparent cellulose-based UV-absorbing films were prepared by dissolving cellulose raw materials using N-methylmorpholine-N-oxide (NMMO) and using ZnO nanoparticles as UV absorbers. Furthermore, transparent actuator was fabricated by growing highly transparent and hydrophobic polytetrafluoroethylene (PTFE) film on regenerated cellulose (RC)-ZnO composite film. In addition to its sensitive response to Infrared (IR) light, the as-prepared actuator also shows a highly sensitive response to UV light, which is attributed to the strong absorption of UV light by ZnO NPs. Thanks to the drastic differences in adsorption capacity between the RC-ZnO and PTFE materials for water molecules, the asymmetrically- assembled actuator demonstrates extremely high sensitivity and excellent actuation performance, with a force density of 60.5, a maximum bending curvature of 3.0 cm−1, and a response time of below 8 s. Bionic bug, smart door and the arm of excavator made from the actuator all exhibit sensitive responses to UV and IR lights.