Polyethylene Terephthalate Sheet Research Articles

Facile preparation and broadband microwave absorption of multilayered materials based on thin films of reduced graphene oxide

Microwave absorption (MA) materials have received extensive attention for their wide applications in both civil and military areas. However, many MA materials have a large thickness, high filling ratio, and narrow effective microwave absorption bandwidth (Reflection Loss, RL ≤ −10 dB) (EAB), and are prepared by complex processes. In this work, a reduced graphene oxide (RGO) film is prepared for the first time by an approach involving floating-dipping and chemical reduction. Compared with previous micrometers-thick RGO films, the present 200 nm-thick dense RGO film is critical for improving not only the impedance matching but also the capability of the material to attenuate incident microwaves. Based on such a thin RGO film, a multilayered material with a jaaumann structure is constructed with individual RGO layers alternating between low dielectric polyethylene terephthalate (PET) sheets. With the superb impedance matching, multilayer attenuation, and multi-cavity resonance, the present multilayered material can achieve a wide EAB of 13.75 GHz with a minimum reflection loss of −47.69 dB using only 3 layers of RGO films. This study provides a new and simple strategy for the development of layered materials with a thin thickness, low filling ratio, and strong absorption with a wide EAB.

Influence of PET as single-use contact material on gloss and surface properties of chocolate

Polyethylene terephthalate (PET) is a commonly used polymer in many industry sectors including confectionery industry. In the latter, PET is utilized for single-use moulds for chocolate manufacturing. Despite the broad application of PET in these areas, information regarding its influence on chocolate gloss and surface properties is not available. Meanwhile, it is already well established that fat crystal modification influence these properties (including gloss) distinctly. To bridge this disparity, this study examined how amorphous and glycol-copolymerized PET sheets influence non-pre-crystallised and pre-crystallised dark chocolate properties throughout a 28-day storage period. Polymorphic properties of cocoa butter were analysed via DSC. Non-pre-crystallised and pre-crystallised chocolate surfaces were characterised regarding colour, gloss, polarity, adhesion, roughness, and topography. While pre-crystallised chocolate shows consistent results, non-pre-crystallised chocolate experiences considerable changes in surface properties due to fat crystal transitions during storage. The findings show that the polymorphic state had a major impact on chocolate surface properties. Furthermore, results demonstrated that the type of PET had a significant impact on chocolate surface properties as well. Pre-crystallised chocolate gloss was significantly impacted by the choice of PET contact material. As a result, pre-crystallised chocolates exhibited a larger tendency to gloss inhomogeneities following amorphous PET monolayer sheet contact.

Electrospun vanadium oxide hollow nanofibers based supercapacitor inspired triboelectric nanogenerator as self-powered visible-blind ultraviolet photodetector

Self-powered visible-blind ultraviolet (UV) photodetectors have emerged as sustainable alternatives in various sectors, including security, surveillance, and environmental monitoring. So, we report a vanadium oxide (V2O5) hollow nanofibers-based supercapacitor-inspired triboelectric nanogenerator (STENG) as a self-powered visible-blind UV photodetector. A novel designed STENG is fabricated using electrospun V2O5 hollow nanofibers-based coated on indium tin oxide coated polyethylene terephthalate sheet (ITO/PET) on top side and a layer of polyvinyl alcohol (PVA) & sulphuric acid over multi-walled carbon nanotubes (MWCNT) coated graphite sheet on bottom side. The optimized STENG demonstrates 34 V peak-to-peak open circuit voltage (Voc) and 2 μA of peak-to-peak short circuit current (Isc) by applying force via finger tapping. However, STENG's performance improves significantly to deliver 280 V Voc (peak-to-peak), and 6 μA Isc (peak-to-peak) with 0.49 W/m2 power density at 100 MΩ load resistance due to electrochemical charging. The output voltage of the STENG increases by 400 % under UV light, which refers to the excellent performance of STENG as a self-powered visible-blind UV photodetector with 266 V/W responsivity at 2.5 mW/cm2 intensity. Hence, the as-fabricated V2O5 hollow nanofibers-based STENG not only paves the way to fabricate a high-performance energy harvester, but can also be used as a self-powered UV-photodetector.

Biodegradation of polyethylene terephthalate (PET) by Brucella intermedia IITR130 and its proposed metabolic pathway.

Accumulation of polyethylene terephthalate (PET) polyester in ecosystems across the globe is a major pollution of concern. Microbial degradation recently generated novel insights into the biodegradation of varieties of plastics. In this study, a PET degrading bacterium Brucella intermedia IITR130 was isolated from a contaminated lake ecosystem at Pallikaranai, Chennai, India. Incubation of the bacterium along with the PET sheet (0.1mm thickness) for 60 days resulted in 26.06% degradation, indicating a half-life of 137.8 days. Considerable changes in the surface morphology of the PET sheet were found as holes, pits, and cracks on incubation with strain IITR130, as revealed by scanning electron microscopy (SEM). After bacterial treatment of PET, the formation of new functional groups, most notably in the area of 3326cm-1 suggestive of O-H stretch, leading to carboxylic acid and alcohol as products were suggested by fourier transform infrared (FTIR) analysis. Monomethyl terephthalate (MMT) and terephthalic acid (TPA) were identified by gas chromatography-mass spectrometry (GC-MS) analysis as PET degradation metabolites. Tributyrin clearance assay confirmed the presence of a lipase/esterase enzyme in the strain IITR130. In this study, a degradation pathway for PET by an isolated and identified bacterium Brucella intermedia IITR130 was characterized in detail.

Determination of Young’s Modulus of PET Sheets from Lamb Wave Velocity Measurement

BackgroundThe elastic modulus of polyethylene terephthalate (PET) sheets is typically measured through destructive tests that require specific sample preparation and time-consuming testing procedures.ObjectiveTo improve the efficiency of measuring the elastic modulus of PET sheets, research on a non-destructive measurement approach using guided Lamb waves was conducted.MethodsIn this approach, the group velocity of the zero-order symmetric Lamb wave mode (S0 mode) at a single frequency is first measured from PET sheets. The semi-analytical finite element method (SAFEM) is used as the forward model to calculate the corresponding numerical group velocity. Particle swarm optimisation (PSO) is used to update the elastic modulus in the SAFEM model until the numerical group velocity from the model matches the experimental results.ResultsThe results show that measuring the group velocity data at a single frequency is sufficient for elastic modulus measurement while the material thickness can be assumed as a constant, which improves the efficiency of the measurement. The identified modulus differs from the tensile modulus of the material due to the frequency dependence of the elastic modulus. However, this discrepancy could be eliminated by using a linear regression model.ConclusionsThe method mentioned above can achieve non-destructive and efficient measurement of the elastic modulus of PET sheets, which can potentially be applied for in-line quality inspection in PET bottle production processes.

Microfabricated free standing, tuneable, porous microfilters from an epoxy based photoresist for effective bioseparation.

SU-8 is an epoxy-based, biocompatible thermosetting polymer, which has been utilized mainly to fabricate biomedical devices and scaffolds. In this study, thin, single-layered, freestanding tuneable porous SU-8 membranes were microfabricated and surface hydrophilized for efficient bioseparation. Unlike the previous thicker membranes of 200-300 μm, these thin SU-8 membranes of 50-60 μm thickness and pores with 6-10 μm diameter were fabricated and tested for blood-plasma separation, without any additional support structure. The method is based on making a patterned SU-8 layer by electrospin coating and UV lithography on a sacrificial polyethylene terephthalate (PET) sheet attached to a silicon wafer. Poor adhesion between PET and SU-8 aid in the convenient release of the thin porous membranes with uniform pore formation. The single-layered self-supporting membranes were strong, safe, sterilizable, reusable, and suitable for plasma separation and postfermentation broth enrichment.

Fabrication and properties of polyethylene terephthalate (PET) aerogel composites from plastic bottle waste

To solve environmental problems of plastic waste, novel polyethylene terephthalate (PET) aerogel composites from recycled PET fibres of plastic bottles are developed successfully for the first time in this work. The PET honeycomb structures with various cell sizes are fabricated by layering and then bonding PET sheets with ethyl cyanoacrylate. The honeycomb cells are filled with the recycled PET fibres and a polyvinyl alcohol (PVA) cross-linker and then freeze-dried at −70 °C, 100 Pa for 48 h to obtain the PET aerogel composites (PACs). Effects of the various honeycomb cell sizes (1.0 – 2.0 cm), and PET-PVA ratios (5–1, 10–1, and 20–1), on the 3-dimensional (3D) mechanical and thermal properties of the PACs are investigated comprehensively. Due to the light-weight PET aerogel (PA) contribution, the PACs have the ultra-low densities of 0.042 – 0.072 g/cm3 and low thermal conductivities of 0.033 – 0.038 W/m·K. The honeycomb structure with the smallest cell size of 1.0 cm exhibits the highest compressive modulus of 15.30 MPa in the out-of-plane direction and 0.070 – 0.128 MPa in the other in-plane directions of the PAC. The compressive strength of the PACs in the out-of-plane direction is up to 730 times greater than those in the other in-plane directions and 2550 times greater than that of the PAs. The developed PACs perform better than aramid honeycomb-reinforced silica aerogel composites and common commercial products. They can be good alternatives for building insulation and cold chain applications.

Permittivity-customizable Low-cost Laminated PET Sheet Multilayer Substrate to Design Flexible and Conformal Planar Inverted F Antenna

Abstract: In this article, a Planar Inverted F Antenna (PIFA) has been designed using low-cost commercially available transparent laminated sheets. Energy Dispersive X-ray (EDX) analysis is used to acquire the element composition of the transparent laminated sheet. Methods: The flexibility is attained using a market-available low-cost Polyethylene Terephthalate (PET) sheet as a substrate. The dielectric properties of this non-conventional laminated sheet need to be identified for antenna design and the microstrip ring resonator test method is used to determine the dielectric properties of the multilayer PET sheets. Results: The linear match has been observed on multilayer laminated PET sheets for dielectric properties and radiation characteristics. Adhesive copper foil of a thickness of 0.08 mm has been used as for conducting layer on the PET lamination sheet. As per the literature survey, it is evident that this is the first attempt to use the reported methodology for PIFA design application. The gain of proposed antenna is 5.2dB. Conclusion: The designed flexible antenna has been developed for wearable and IoT applications in 2.45 GHz ISM band. A good match has been observed between the simulated and measured characteristics.

Design and fabrication of TiO2/Nd polyurethane nanofibers based photoreactor: A continuous flow kinetics study for Estriol degradation and mechanism

Novel polyurethane (PU) nanofibers incorporated with the neodymium (Nd) doped TiO2 nanoparticles were fabricated by electrospinning process and employed for the photocatalytic degradation of the estriol (E3) hormone. Nanofibers possessed high porosity (0.47 μm) and uniform mesh-like structure while suitable incorporation of TiO2/Nd nanoparticles with increasing concentrations (5, 10, and 20 %) was obtained. The TiO2/Nd incorporated PU nanofiber photocatalytic activity under UV and visible light was evaluated using a continuous drip flow biofilm reactor. To establish sufficient adherence to the PU matrix necessary to maintain durability during crossflow reactor, the as-prepared nanofibers were thermally pressed on polyethylene terephthalate (PET) sheets to avoid any potential folding. The nanofibers performed better in UV than visible, with maximum degradation rates of ∼90.2 % and 30.4 %, respectively, at pH 7 in 120 min. The degradation performance of nanofibers increased with an increase in the number of layers and decreased with the E3 solution flow rate. The experimental data best fitted for the pseudo-first-order kinetic model with regression coefficient (R2) > 0.9. The highest degradation removal capacities were 2.436 and 0.847 mg/g under UV and visible light irradiation, respectively. The results showed that TiO2/Nd incorporated PU nanofibers exhibit a potential to degrade hormones from environmental water.

A facile and automated microfluidic electrochemical platform for the in-field speciation analysis of inorganic arsenic

An automated microfluidic electrochemical platform was developed for the rapid in-field analysis of arsenic speciation. Herein, we integrated an electrochemical sensing and microfluidic channel for the simultaneous determination of As(III) and total inorganic As (total iAs) within a single device. The platform was fabricated by assembling a gold nanoparticle-modified screen-printed graphene electrode (AuNP/SPGE) on a hydrophilic polyethylene terephthalate (PET) sheet that was specially designed to enclose a microfluidic channel with dual flow channels for separate determination of the two species. While As(III) can be promptly detected with the AuNP/SPGE on one end, thioglycolic acid stored in glass fiber is employed on the other end to reduce As(V) before being electrochemically analyzed on the AuNP/SPGE as total iAs; the difference represents the amount of As(V). With a wireless potentiostat and a smartphone equipped with Bluetooth technology, the overall procedure can be fully automated and accomplished merely within 9 min. The linear ranges for the determination of As(III) and total iAs were found to be 50–1000 and 100–1500 ng/mL with detection limits of 3.7 and 17 ng/mL, respectively. The proposed method was validated and applied for the inorganic As speciation of various food samples with satisfactory results compared to those obtained with the standard HPLC-ICP‒MS protocol. This novel microfluidic electrochemical platform offers numerous advantages, notably for its simplicity, speed, low cost, and portability for on-site analysis, which conclusively makes it a highly promising analytical device for the speciation of inorganic arsenic.

Water‐Based Conductive Ink Formulations for Enzyme‐Based Wearable Biosensors

AbstractHerein, this work reports the first example of second‐generation wearable biosensor arrays based on a printed electrode technology involving a water‐based graphite ink, for the simultaneous detection of l‐lactate and d‐glucose. The water‐based graphite ink is deposited onto a flexible polyethylene terephthalate sheet, namely stencil‐printed graphite (SPG) electrodes, and further modified with [Os(bpy)2(Cl)(PVI)10] as an osmium redox polymer to shuttle the electrons from the redox center of lactate oxidase from Aerococcus viridans (LOx) and gluocose oxidase from Aspergillus niger (GOx). The proposed biosensor array exhibits a limit of detection as low as (9.0 ± 1.0) × 10−6 m for LOx/SPG‐[Os(bpy)2(Cl)(PVI)10] and (3.0 ± 0.5) × 10−6 m for GOx/SPG‐[Os(bpy)2(Cl)(PVI)10], a sensitivity as high as 1.32 μA mm−1 for LOx/SPG‐[Os(bpy)2(Cl)(PVI)10] and 28.4 μA mm−1 for GOx/SPG‐[Os(bpy)2(Cl)(PVI)10]. The technology is also selective when tested in buffer and artificial sweat and is endowed with an operational/storage stability of ≈80% of the initial signal retained after 20 days. Finally, the proposed array is integrated in a wristband and successfully tested for the continuous monitoring of l‐lactate and d‐glucose in a healthy volunteer during daily activity. This is foreseen as a real‐time wearable device for sport‐medicine and healthcare applications.

New conductive ink based on carbon nanotubes and glass varnish for the construction of a disposable electrochemical sensor

This work presents the manufacture of a new conductive ink based on glass varnish and carbon nanotubes, employed for the construction of an electrochemical sensor printed on polyethylene terephthalate (PET) sheets. In this context, the exploration of the electrochemical and analytical performance of this new, low-cost conductive ink is of great interest. The sensors prepared with the proposed ink were studied by cyclic voltammetry (CV) using ferrocenemethanol (FcMeOH) as a redox probe. The proposed sensor was applied for the detection of 3-nitro-l-tyrosine (3-NLT), a modified amino acid present in biological fluids that can serve as an indicator of oxidative stress, using square wave voltammetry (SWV). Under optimized conditions, the sensor presented a linear response ranging from 0.70 to 100.0 μmol L-1, with a limit of detection (LOD) of 0.53 μmol L-1. The sensor was applied in the analysis of 3-NLT in synthetic urine, and recovery values ranging from 95.2 to 106.0% were obtained. Also, an analytical curve in human blood serum was constructed to show the suitability of the method in complex matrices. Linear responses ranging from 3.0 to 100.0 μmol L-1 of 3-NLT and a LOD of 1.35 μmol L-1 were obtained. Furthermore, the device was simple to produce and presented a relatively low cost. The obtained data demonstrate that the developed ink showed satisfactory analytical application, corroborating with further investigations and the advance in the production of other conductive inks in laboratory settings.

In Situ Synthesis of ZIF-67 Thin Films Using Low Temperature Chemical Vapor Deposition to Fabricate All-Solid-State Flexible Interdigital in-Planar Microsupercapacitors

This work describes the fabrication of a flexible all-solid-state interdigital in-planar microsupercapacitor (μSC) using the in situ synthesized ZIF-67 thin films as the interdigital finger-electrode materials, platinum (Pt) thin film as the interdigital finger-electrode current collector, laser print technology for the fabrication of interdigital patterns, and low-cost commercial polyethylene terephthalate (PET) sheet as the flexible substrates, assembled with the NaOH/PVA gel electrolyte. ZIF-67 thin films are in situ synthesized onto PET substrate by ultralow temperature (ULT) chemical vapor deposition (CVD) technology at a low temperature of 140°C. We herein report the ULT CVD approach for gas phase synthesizing ZIF-67 thin films, the exactly heating temperature can produce vaporized water steam, sublimated 2-methylimidazole (2-MIM) and cobalt(II) acetylacetonate (Co(acac)2) vapors at the same time. The vaporized and sublimated gaseous precursors demonstrated molecular-level reactions, including the deprotonation of 2-MIM via water steam, and the following coordinated reactions with cobalt ions decomposed from Co(acac)2, for the efficiently straightforward deposition to form the uniform ZIF-67 thin films onto the substrate surface. Herein, the integration of pattern printing, CVD depositing ZIF-67 thin films, and lift-off patterning processes demonstrated a comprehensive achievement and good compatibility to integrate MOFs into miniaturized energy-storage devices.

Ultrasensitive and Cost-Effective Detection of Neuropeptide-Y by a Disposable Immunosensor: A New Functionalization Route for Indium-Tin Oxide Surface.

Neuropeptide Y (NPY) is one of the most abundant neuropeptides in the human brain, and its levels in the blood change in neurodegenerative and neuroimmune disorders. This indicates that NPY may serve as a diagnostic and monitoring marker for associated disorders. In this paper, an electrochemical immunosensor was created to detect NPY biomarkers using a novel immobilization technique. The proposed biosensor system enables accurate, specific, cost-effective, and practical biomarker analysis. Indium tin oxide-coated polyethylene terephthalate (ITO-PET) sheets were treated with hexamethylene diisocyanate (HMDC) to covalently immobilize antibodies. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) techniques were used to analyze each step of the biosensors. The proposed NPY biosensor has a broad linear detection range (0.01-100 pg mL-1), a low limit of detection (LOD) (0.02968 pg mL-1), and a low limit of quantification (LOQ) (0.0989 pg mL-1). Atomic force microscopy (AFM) was used to support in the optimization process, study the surface morphology, and visualize it. Studies of repeatability, reproducibility, storage, and Kramers-Kronig transformation were conducted during electrochemical characterization. After analytical experiments, the biosensor's responses to human serum samples were evaluated. According to the obtained data, the error margin is small, and the created biosensor offers a great deal of promise for the clinical measurement of NPY.

Multipurpose nanocomposite resist for free-standing transparent conductive thin films

Nanocomposites formed by silver nanowires (AgNWs) embedded in a polymer matrix are a convenient way to deposit thin films with electrical conductance and high transparency on different substrates. Nanocomposite resists containing AgNWs in a poly(methyl methacrylate) solution can be effectively used to produce conductive coatings in a straightforward manner. Here, we show that by adding a sacrificial layer of polyvinylpyrrolidone on a glass substrate, prior to the nanocomposite resist, it is possible to obtain large-area free-standing films of about 450 nm with electrical conductance and high transparency. The films can be transferred to different surfaces and materials including non-flat substrates. The formation of conductive stacks by piling two layers was also demonstrated. The optical, electrical, and structural properties of these free-standing films were studied obtaining films with transmittance T(%) = 78% at 550 nm, sheet resistance Rs = (670 ± 40) Ω sq−1 and surface roughness Ra = (50 ± 10) nm. We studied the strain resistance behavior of films transferred to polyethylene terephthalate sheets under bending tests finding a sensitivity of (0.51 ± 0.01) Ω deg−1 and a gradual increase in the resistance during cycling. In addition, thin flexible supports can be added by covering the nanocomposite film with polydimethylsiloxane (PDMS) prior to its release, enhancing the mechanical robustness and improving the manipulation of the films.

Thermal Effect on Thin-Film Formation of the Polymer Sheets by the CO2 Laser with the Copper Base.

A method that makes polymer sheets partially thinner with continuous-wave carbon dioxide (CO2) lasers has been developed. This method can create thin polymer films by attaching the polymer sheets to the copper base by vacuum suction through the holes in the base. Applying the method to polypropylene (PP), polyethylene terephthalate (PET), polystyrene (PS), and polytetrafluoroethylene (PTFE), the thin-film formation is confirmed in PP, PET, and PS but not PTFE. These polymers have the similar thermal properties. PP, PET, and PS show fluidity with increased temperature, but PTFE does not have fluidity. These characteristics of the polymers indicate that the fluidity of polymer is the important characteristic for film formation. The experiments with PP and PET sheets of different thickness show that thicker sheets make thicker films. The fluid flow of the molten polymer is considered to form the thin film at the bottom of the groove made by laser scribing. The numerical simulation of the 2D thermal model also indicates the week cooling effects of the base on the film formation and importance of polymer fluidity. The results of Fourier transform infrared spectrometer (FT-IR) show thermal degradation of the films. To decrease the heat’s effect on the films, the polymer sheets should be processed at the highest laser-beam scanning speed that can make thin films.

Effect of Low-Intensity Pulsed Ultrasound on the Graft-Bone Healing of Artificial Ligaments: An In Vitro and In Vivo Study

Background: As many researchers have focused on promoting the graft-bone healing of artificial ligaments, even with numerous chemical coatings, identifying a biosafe, effective, and immediately usable method is still important clinically. Purpose: (1) To determine whether a low-intensity pulsed ultrasound system (LIPUS) promotes in vitro cell viability and osteogenic differentiation and (2) to assess the applicability and effectiveness of LIPUS in promoting the graft-bone healing of artificial ligaments in vivo. Study Design: Controlled laboratory study. Methods: Polyethylene terephthalate (PET) sheets and grafts were randomly assigned to control and LIPUS groups. MC3T3-E1 preosteoblasts were cultured on PET sheets. Cell viability and morphology were evaluated using a live/dead viability assay and scanning electron microscopy. Alkaline phosphatase activity, calcium nodule formation, and Western blot were evaluated for osteogenic differentiation. For in vivo experiments, the effect of LIPUS was evaluated via an extra-articular graft-bone healing model in 48 rabbits: the osteointegration and new bone formation were tested by micro–computed tomography and histological staining, and the graft-bone bonding was tested by biomechanical testing. Results: Cell viability was significantly higher in the LIPUS group as compared with control (living and dead compared between control and LIPUS groups, P = .0489 vs P = .0489). Better adherence of cells and greater development of extracellular matrix were observed in the LIPUS group. Furthermore, LIPUS promoted alkaline phosphatase activity, calcium nodule formation, and the protein expression of collagen 1 (P = .0002) and osteocalcin (P = .0006) in vitro. Micro–computed tomography revealed higher surrounding bone mass at 4 weeks and newly formed bone mass at 8 weeks in the LIPUS group (P = .0014 and P = .0018). Histological analysis showed a narrower interface and direct graft-bone contact in the LIPUS group; the surrounding bone area at 4 weeks and the mass of newly formed bone at 4 and 8 weeks in the LIPUS group were also significantly higher as compared with control (surrounding bone, P < .0001; newly formed bone, P = .0016 at 4 weeks and P = .005 at 8 weeks). The ultimate failure load in the LIPUS group was significantly higher than in the control group (P < .0001 at 4 weeks; P = .0008 at 8 weeks). Conclusion: LIPUS promoted the viability and osteogenic differentiation of MC3T3-E1 preosteoblasts in vitro and enhanced the graft-bone healing of PET artificial ligament in vivo. Clinical Relevance: LIPUS is an effective physical stimulation to enhance graft-bone healing after artificial ligament implantation.

A low-profile consolidated metastructure for multispectral signature management

This work pertains to the design, numerical investigation, and experimental demonstration of an optically transparent, lightweight, and conformable metastructure that exhibits multispectral signature management capabilities despite its extremely low-profile configuration. In comparison to the existing hierarchical approaches of designing multispectral stealth solutions, attention has been paid to accommodate the conflicting requirements of radar and infrared (IR) stealth using a single metasurface layer configuration, which required a few constraints to be incorporated during the design stage to ensure compatibility. This methodology promulgates the desired multispectral response with minimal manufacturing footprint and facilitates an efficient integration with the other existing countermeasure platforms. The resulting design exhibits a polarization-insensitive and incident angle stable broadband microwave absorption with at least 90% absorption ranging from 8.2 to 18.4 GHz. Concomitantly it also exhibits an averaged IR emissivity of 0.46 in the 8–14 µm long-wave IR regime, along with high optical transparency (71% transmission at 632.8 nm). Notably, the total thickness of the metastructure stands at 0.10 ( corresponds to the wavelength at lowest frequency). The metastructure has been fabricated with indium tin oxide coated polyethylene terephthalate sheets, on which the frequency selective pattern is machined using Excimer laser micromachining, and the performances are verified experimentally. Furthermore, a hybrid theoretical model has been developed that not only provides crucial insights into the operation of metastructure but also presents a methodical semi-analytical approach to design.

Effect of chord-wise flexibility in the lift generation of flapping MAV with membrane wing

PurposeThe purpose of this study is to experimentally analyse the effect of flexible and stiffened membrane wings in the lift generation of flapping micro air vehicle (MAV).Design/methodology/approachThis is analysed by the rectangle wing made up of polyethylene terephthalate sheets of 100 microns. MAV is tested for the free stream velocity of 2 m/s, 4 m/s, 6 m/s and k* of 0, 0.25, 1, 3, 8. This test is repeated for flapping MAV of the free flapping frequency of 2 Hz, 4 Hz, 6 Hz, 10 Hz and 12 Hz.FindingsThis study shows that the membrane wing with proper stiffeners can give better lift generation capacity than a flexible wing.Research limitations/implicationsOnly a normal force component is measured, which is perpendicular to the longitudinal axis of the model.Practical implicationsIn MAVs, the wing structures are thin and light, so the effect of fluid-structure interactions is important at low Reynold’s numbers. This data are useful for the MAV developments.Originality/valueThe effect of chord-wise flexibility in lift generation is the study of the effect of a flexible wing and rigid wing in MAV. It is analysed by the rectangle wing. The coefficient of normal force at different free stream conditions was analysed.

Influence of electrochemical co-deposition of bimetallic Pt–Pd nanoclusters on polypyrrole modified ITO for enhanced oxidation of 4-(hydroxymethyl) pyridine

Bimetallic Pt–Pd nanoparticles were dispersed on polypyrrole coated indium-tin oxide coated polyethylene terephthalate sheets (ITO-PET sheets). The excellent filming property of pyrrole gives a high porous uniform active area for the proper adsorption of bimetallic transition metal nanoparticles. Electrochemical behavior of the modified electrodes was determined using cyclic voltammetry and impedance studies. The physicochemical properties of the modified electrodes were analyzed by scanning electron microscopy, X-ray diffraction spectroscopy, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. To study the electrochemical oxidation of 4-(hydroxymethyl) pyridine in the presence of sodium nitrate in aqueous acidic medium, the modified electrode was used. It is evident from the study that the modified electrode shows better electrochemical activity towards the oxidation of 4-(hydroxymethyl) pyridine.