Polyethylene Naphthalate Research Articles

Mechanoenzymatic Depolymerization of Highly Crystalline Polyethylene Naphthalate under Moist-Solid Conditions

Mechanoenzymatic Depolymerization of Highly Crystalline Polyethylene Naphthalate under Moist-Solid Conditions

Measurement of the water vapor transmission rate at temperatures above 100 °C

ABSTRACT Water vapor transmission rate (WVTR) and water vapor permeability coefficient were measured at temperatures between 110 and 138°C using the modified cup method. The cup, placed in a Highly Accelerated Stress Test chamber, allowed water vapor to permeate the sample film attached to the cup. The WVTR was determined based on the increase in mass of the cup. To prevent sample damage during measurement, a cup with a pressure adjustment mechanism was utilized. Carrier-incorporated phosphorus pentoxide was used as the desiccant instead of anhydrous calcium chloride to ensure a consistent moisture absorption rate, especially at high temperatures. The water vapor permeability coefficients for the polycarbonate, polyimide, and adhesive films were distributed on an approximately straight line in the Arrhenius plot. Additionally, the Arrhenius plots for the polyethylene terephthalate and polyethylene naphthalate films captured the permeability bending point near the glass transition temperature. To accurately measure the high-temperatureWVTR, upper and lower limits were established for the weighing interval, cup mass gain, and WVTR measurement range.

Estimation of confined compressive strength of LRS‐FRP concrete specimens with computational intelligence

AbstractReinforced concrete structures deteriorate due to changes in temperature, corrosion, and attacks of sulfate and chloride contents. Retrofitting techniques like fiber‐reinforced polymer (FRP) jacketing, known for their strength and corrosion resistance, are increasingly used to strengthen and retrofit deteriorated structural elements. Large rupture strain (LRS)‐FRP composite, composed of polyethylene terephthalate and polyethylene naphthalate, both of which have high tensile strength and high strain at rupture have been used in the studies of many researchers. This research aims to develop a reliable and accurate machine learning (ML) model to estimate the compressive strength of LRS‐FRP confined specimens. A total of 303 LRS‐FRP confined specimens were gathered after a thorough literature review to develop ML models, utilizing the linear regression, support vector regression, regression tree, and artificial neural network (ANN) algorithms. Additionally, 44 analytical models (AMs) were used to compare the performance of the developed ML models. The results revealed that the performance of the developed ANN model was higher among all the ML and AMs. The R‐value and the mean absolute percentage error (MAPE) value of the developed ANN model were 0.9822 and 6.17%, respectively. The sensitivity analysis results show that the height of the specimens had the highest impact followed by the diameter of the specimen, the number of FRP layers and thickness, and then the tensile strength of LRS‐FRP. The ANN‐based mathematical expression is simple and easy to use to predict the compressive strength of the LRS‐FRP strengthened specimens.

Double glass transition in polyethylene naphthalate by MDSC, BDS, and TSDC.

In this work, we present an experimental study of the primary and secondary relaxations of the semi-crystalline polymer polyethylene naphthalate by modulated differential scanning calorimetry, Thermally Stimulated Depolarization Currents (TSDCs), and Broadband Dielectric Spectroscopy (BDS) and how they are affected by physical aging. Three dipolar relaxation modes can be observed: from slowest to fastest: the primary α relaxation, which vitrifies at the glass transition temperature, Tgα, and two secondary relaxations, named β* and β. Modulated differential scanning calorimetry results show how the secondary β* relaxation also vitrifies, giving rise to an additional glass transition at Tgβ* < Tgα. In fact, the α and β* relaxations can be considered as part of a very broad and distributed relaxation. Its main part is the primary α relaxation with a shoulder at the high-frequency region corresponding to a complex secondary β* relaxation. BDS results about β* can be modeled by a main contribution (β3*) and two additional ones (β1* and β2*) with a weaker dielectric strength. TSDC results show that each single mode of the relaxation has its own glass transition temperature and they are compatible with the structure inferred by BDS. This scenario gives rise to an extended glass transition dually centered in the Tgβ* ∼ 305K and Tgα ∼ 387K temperatures.

A super-toughened polyethylene naphthalene (PEN) enabled by polyacrylate elastomer with low crosslink density and reactivity

In elastomer toughening of polyester plastics, both the particle size distribution of the elastomer and the interfacial strength between the elastomer and matrix are key factors for toughness. In this work, bi-functional polyacrylate elastomers with controllable crosslinking density and reactivity were designed for enhancing the toughness of polyethylene naphthalene (PEN) matrix. Firstly, the elastomers with crosslinked structure possess increased melt viscosity and endowed wide particle size distribution, which contribute to the construct of thin matrix ligament and make PEN matrix more susceptible to shear-yield. Secondly, the high interfacial strength between elastomer and matrix can facilitate the transfer of external stress from PEN matrix to the elastomer, protecting the matrix from destroying. The resulted PEN blends exhibit an excellent impact resistance of 45.20 kJ/m2 and a high tensile toughness of 3.586 MJ/m3, which are 21.73 times and 47.81 times higher, respectively, than the virgin PEN. The present work may provide an effective approach for designing polyester blends with enhanced impact resistance and tensile toughness.

Adjusting microwave sensing frequency through aspect ratio variation and bending repetitions in Permalloy ellipses

The Ferromagnetic Resonance (FMR) phenomenon, marked by the selective absorption of microwave radiation by magnetic materials in the presence of a magnetic field, plays a pivotal role in the development of radar absorbing materials, high speed magnetic storage, and magnetic sensors. This process is integral for technologies requiring precise control over microwave absorption frequencies. We explored how variations in resonance fields can be effectively modulated by adjusting both the shape and stress anisotropies of magnetic materials on a flexible substrate. Utilizing polyethylene-naphthalate (PEN) as the substrate and Permalloy (Ni79Fe21, noted for its positive magnetostriction coefficient) as the magnetic component, we demonstrated that modifications in the aspect ratio and bending repetitions can significantly alter the resonance field. The results, consistent with Kittel’s equation and the predictions of a uniaxial magnetic anisotropy model, underscore the potential for flexible substrates in enhancing the sensitivity and versatility of RF-based magnetic devices.

Synaptic plasticity in zinc oxide-based flexible invisible transparent memristor by modulating oxygen concentration

Artificial synapses based on memristors are used in emulating the synaptic plasticity behavior of a human brain. Here, we have proposed a transparent memristor based on aluminum zinc oxide (AZO) on a flexible substrate—polyethylene naphthalate. We have analyzed the elemental composition of the gadget subjected to the optimized flow rate of Ar/O2 = 2/1 by x-ray photoelectron spectroscopy. The prepared AZO/ZnO/indium-doped tin oxide memristor exhibits a bipolar switching behavior with Vset/Vreset of 1.4/−2.0 V. The results reflect an acceptable endurance of &amp;gt;500 cycles and retention of 104 s. The optimized device shows an improvement in the non-linearity of potentiation—2.31/depression—3.05 and has more than 25 cycles of stability. The transparency is checked using a UV-visible spectrophotometer showing 90% transparency in the visible region making the device suitable for applications in invisible electronics. Our results reflect that the proposed device can be used as a transparent electrode in making artificial synapses for neuromorphic applications.

Evaluation of Transducer Elements Based on Different Material Configurations for Aptamer-Based Electrochemical Biosensors.

The selection of an appropriate transducer is a key element in biosensor development. Currently, a wide variety of substrates and working electrode materials utilizing different fabrication techniques are used in the field of biosensors. In the frame of this study, the following three specific material configurations with gold-finish layers were investigated regarding their efficacy to be used as electrochemical (EC) biosensors: (I) a silicone-based sensor substrate with a layer configuration of 50 nm SiO/50 nm SiN/100 nm Au/30-50 nm WTi/140 nm SiO/bulk Si); (II) polyethylene naphthalate (PEN) with a gold inkjet-printed layer; and (III) polyethylene terephthalate (PET) with a screen-printed gold layer. Electrodes were characterized using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) to evaluate their performance as electrochemical transducers in an aptamer-based biosensor for the detection of cardiac troponin I using the redox molecule hexacyanoferrade/hexacyaniferrade (K3[Fe (CN)6]/K4[Fe (CN)6]. Baseline signals were obtained from clean electrodes after a specific cleaning procedure and after functionalization with the thiolate cardiac troponin I aptamers "Tro4" and "Tro6". With the goal of improving the PEN-based and PET-based performance, sintered PEN-based samples and PET-based samples with a carbon or silver layer under the gold were studied. The effect of a high number of immobilized aptamers will be tested in further work using the PEN-based sample. In this study, the charge-transfer resistance (Rct), anodic peak height (Ipa), cathodic peak height (Ipc) and peak separation (∆E) were determined. The PEN-based electrodes demonstrated better biosensor properties such as lower initial Rct values, a greater change in Rct after the immobilization of the Tro4 aptamer on its surface, higher Ipc and Ipa values and lower ∆E, which correlated with a higher number of immobilized aptamers compared with the other two types of samples functionalized using the same procedure.

Assessing the Effect of Twisting and Twisting Fatigue on ZnO:Al Thin Film Performance on PEN and PET Substrates.

This study examines the electromechanical characteristics of aluminium-doped zinc oxide (AZO) films. The films were produced using the RF magnetron sputtering process with a consistent thickness of 150 nm on various polymer substrates. The study focuses on assessing the electro-mechanical failure processes of coated segments using flexible substrates, namely polyethylene naphthalate (PEN) and polyethylene terephthalate (PET), with a specific emphasis on typical cracking and delamination occurrences. This examination involves conducting twisting deformation together with using standardised electrical resistance measurements and optical microscope monitoring instruments. It was found that the crack initiation angle is mostly dependent on the mechanical mismatch between the coating and substrate. Higher critical twisting angle values are observed for the AZO/PEN film during twisting testing. Relative to the perpendicular plane of the untwisted sample, it was found that cracks initiated at a twist angle equal to 42° ± 2.1° and 38° ± 1.7° for AZO/PEN and AZO/PET, respectively, and propagated along the sample length. SEM images indicate that the twisting motion results in deformation in the thin film material, leading to the presence of both types of stress in the film structure. These discoveries emphasise the significance of studying the mechanical properties of thin films under different stress conditions, as it can impact their performance and reliability in real-world applications. The electromechanical stability of AZO was found to be similar on both substrates during fatigue testing. Studying the electromechanical properties of various material combinations is important for selecting polymer substrates and predicting the durability of flexible electronic devices made from polyester.

An Ultrasensitive Perovskite Single‐Model Plasmonic Strain Sensor Based on Piezoelectric Effect

AbstractInterest in flexible photonics has been motivated by the development of artificial smart skins. In particular, coupling of photonics and mechanics can offer opportunities to realize ultrasensitive strain sensor, however, low‐cost fabrication of flexible sensing device with desired photonic functionality remains a challenge. Hereby, the study reports an ultrasensitive strain‐gauge sensor based on the poly(ethylenenaphthalate (PEN))/monocrystal Au/MgF2/CsPbBr3 nanorod/Al2O3/polyacrylonitrile (in short P/mAu/M/CPB@Al2O3@PAN), which are sensitive to nanoscale structure alterations of PEN substrate via the stress response of the single‐mode laser based on the piezoelectric‐effect. Wherein a low‐threshold single‐mode lasing (Pth ≈ 170 nJ cm−2) is achieved through coating Al2O3 on the CsPbBr3 nanorod, producing the higher quality factor (Q ≈ 1637) to guarantee a much higher sensitivity in sensing application. Reversible spectral regulating of ≈3 nm in single‐mode‐lasing wavelength, with a subnanometre scale resolution &lt;0.4 nm and the wavelength sensitivity (Sλ) as high as 160 nm RIU−1, is validated in response to applied strain ranging from −1.31% to 1.31%. This work not only represents essential progress in construction of ultrasensitive and cost‐effective flexible photonic sensor, but also lays the foundation for the potential application in smart photonic skins.

Flexible urea biosensor based on CuS/Bioglass 45S5.TiO2 Nps thin films

Chronic renal insufficiency has been a high-incidence disease around the world in recent years. With the lack of devices to detect these illnesses opportunely, developing urea biosensors is imperative. This work reports the application of copper sulfide (CuS) thin films deposited via a chemical bath and Bioglass 45S5/titanium dioxide nanoparticles thin films in a urea flexible biosensor. The Bioglass 45S5 was deposited over CuS and applied onto polyethylene naphthalate (PEN) and polyethylene terephthalate (PET) with indium tin oxide (ITO) substrates. The systems PEN/CuS/Bioglass 45S5.TiO2 NpS and PET/ITO/CuS/ Bioglass 45S5.TiO2 were characterized optically by UV-Vis. The CuS presented an absorption border around 600 nm and a decrease in transmittance percentage by adding Bioglass. Scanning Electron Microscopy carried out the microstructural characterization; both systems displayed a porous morphology featuring channels suitable for immobilizing the enzyme. The sensors showed a resistive behavior based on the current-voltage curve. The urease enzyme was immobilized by adsorption. The optical changes after adding urease were measured by UV-Vis, obtaining ammonia from the reaction between urease and urea, showing an absorption border around 850 nm. Changes in urea concentrations between 1 and 10 mM caused an increase in resistivity in both samples, obtaining a sensitivity of 12.887 kΩ/sq/mM and 12.411 kΩ/sq/mM, and a linearity of 0.9946 % and 0.9601 % for the samples deposited over PEN and PET ITO, respectively. A Cole-Cole plot showed a behavior corresponding to an equivalent circuit composed of a parallel combination of a resistor and a capacitor in series with a phase constant element; this latter could be attributed to the measurement electrodes. Each sensor was implemented in a Wheatstone bridge. A voltage decrease was obtained for the sample deposited over PET ITO, with a sensitivity of −102.7 mV/mM, and a voltage increase was obtained in the sample deposited over PEN, with a sensitivity of 30.5 mV/mM.

A study of kapton as a flexible substrate for perovskite solar cells; advantages and disadvantages

The increasing usage of perovskite solar cells is being driven by their high efficiency and cost-effective manufacture. Polyethylene Terephthalate (PET) and Polyethylene Naphthalate (PEN) are flexible, transparent, and cost-effective. However, issues have been raised about their long-term stability, especially to the sensitivity of perovskite materials to environmental conditions like as moisture and heat, as well as the challenge of oxygen and moisture transmission across these substrates. Researchers are investigating Polyimide (PI), particularly colorless PI, for enhanced stability, but the techniques are costly. Kapton, a popular colored PI, provides excellent thermal and electrical insulation, but its reduced transparency provides optical issues. In this study, finite-difference-time-domain (FDTD) modeling and experimental analysis were utilized to investigate the optical properties and efficiency of perovskite solar cells on Kapton, PET, and glass substrates. According to the modeling, using Kapton instead of traditional substrates leads to a decrease of 16.6 % in the solar cells short circuit current (JSC). In laboratory experiments, by adding lithium (Li) as the dopant in the electron transport layer (ETL), the sheet resistance of the ETL was reduced from 214 to 2.4 kΩ/□. According to modeling, this enhancement resulted in a 3 % increase in the power conversion efficiency (PCE) of the solar cell, increasing to 17.4 % compared to 16.8 % on a PET substrate. Furthermore, using a Kapton substrate improves critical performance parameters like open circuit voltage (VOC) and fill factor (FF).

P‐158: Highly Flexible InP‐Based Quantum Dot Light‐Emitting Diodes Fabricated on Heat‐Dissipating Al‐Coated PEN Substrate

Quantum dot light‐emitting diodes (QLEDs) have garnered significant attention due to their outstanding optical and electrical properties. Furthermore, there have been many attempts to fabricate QLEDs on the flexible substrates for the application of wearable devices. However, flexible QLEDs face the challenge of instability under thermal heat, due to the low thermal conductivity of the substrates. In this study, we present the InP‐based QLEDs on 1 µm thick polyethylene naphthalate substrates, coated with aluminum for the heat dissipation. The coated Al layer can effectively dissipate the generated heat due to its high conductivity, while maintaining the flexibility of the substrates.

Development of a phoswich detector utilizing bismuth germanate crystal scintillator and polyethylene naphthalate scintillation film

In this study, we present the development of a phoswich detector system employing a Bismuth Germanate (BGO) crystal scintillator in combination with a Polyethylene naphthalate (PEN) film plastic scintillator. Phoswich detectors can contribute to various applications, including radiation monitoring, medical imaging, and nuclear physics experiments, due to their ability to discriminate between different types of radiation. The thin PEN film is sensitive to α and β radiation, while the BGO scintillator exhibits good γ radiation detection efficiency. The incident radiation type and its energy can be determined by analyzing the difference in decay times between these two scintillators. This paper presents an analysis of the detector’s response to α, β, and γ radiation, and the particle tagging efficiencies are to be over 99.9%, 92%, and 99.8%, respectively.

Development of a Method to Measure Trace Levels of Uranium and Thorium in Scintillation Films

Abstract We have established a method to measure picograms-per-gram (pg g−1) levels of 238U and 232Th in scintillation films by combining the dry ashing method and inductively coupled plasma mass spectrometry. Trace amounts of 238U and 232Th were measured in up to 2 g of scintillation film with almost 100% collection efficiency. This paper details the experimental procedure, including the pretreatment of the samples and labware, detection limit of the method, collection efficiencies of 238U and 232Th, and measurement of 238U and 232Th in a polyethylene naphthalate film. This method is also applicable to 238U and 232Th measurements in other low-background organic materials for rare-event search experiments.

Electronic properties of polyethylene naphthalate as derived from photo-stimulated discharge, luminescence experiments and quantum chemical calculation

The electronic properties of thin films of poly(ethylene 2,6-naphthalate)—PEN, are investigated based on their photo-physical (optical absorption, photoluminescence) and electrical (space charge distribution, photo-stimulated discharge) behavior. Photo-stimulated currents are associated with optical absorption of the material leading to space charge dissipation as demonstrated by space charge distribution measurement. Based on this set of experimental results and quantum chemical calculation performed on PEN macromolecular system, we propose a new scheme for the electronic levels of PEN. This scheme allows understanding the mechanisms at play in photo-stimulated discharge. One of the main conclusions of our work is that photo-stimulated current measurements do not probe the energy level of traps. Detrapping of charges results from a two-step process where the photon energy is absorbed by chromophores that restitute a part of this energy to trapped charges through various mechanisms. Moreover, the new scheme allows discussing the components of the luminescence excited under different stresses, being electric field, electronic and UV irradiation, charge recombination and thermal activation.

A novel cryogenic VUV spectrofluorometer for the characterization of wavelength shifters

We present a novel cryogenic VUV spectrofluorometer designed to characterize wavelength shifters (WLS) crucial for experiments based on liquid argon (LAr) scintillation light detection. Wavelength shifters like 1,1,4,4-tetraphenyl-1,3-butadiene (TPB) or polyethylene naphthalate (PEN) are used in these experiments to shift the VUV scintillation light to the visible region. Precise knowledge of the optical properties of the WLS at liquid argon's temperature (87 K) and LAr scintillation wavelength (128 nm) is necessary to model and understand the detector response. The cryogenic VUV spectrofluorometer was commissioned to measure the emission spectra and relative wavelength shifting efficiency (WLSE) of samples between 300 K to 87 K for VUV (120 nm to 190 nm) and UV (310 nm) excitation. New mitigation techniques for surface effects on cold WLS were established. As part of this work, the TPB-based wavelength shifting reflector (WLSR) featured in the neutrinoless double-beta decay experiment LEGEND-200 was characterized. The WLSE was observed to increase by (54 ± 5) % from room temperature (RT) to 87 K. PEN installed in LEGEND-200 was also characterized, and a first measurement of the relative WLSE and emission spectrum at RT and 87 K is presented. The WLSE of amorphous PEN was found to be enhanced by at least (37 ± 4) % for excitation with 128 nm and by (52 ± 3) % for UV excitation at 87 K compared to RT.

Development of wavelength-shifting PEN foils for next generation experiments

Polyethylene naphthalate (PEN) foils have been demonstrated as a wavelength shifter suitable for operation in liquid argon. At the same time, wavelength shifting efficiency of technical grades of PEN, commercially available on the market, is lower than that of tetraphenyl butadiene (TPB). This paper reports on an R&D program focused on exploring the intrinsic limitations of PEN and optimizing it for the highest achievable wavelength shifting efficiency.

Cryogenic setup for the characterization of wavelength-shifting materials for noble element radiation detectors

In the present work, we describe a new cryogenic setup for studies of wavelength-shifting materials for optimised light collection in noble element radiation detectors, and discuss the commissioning results. This SiPM-based setup usesαinduced scintillation in gaseous argon as the vacuum ultraviolet light source with the goal of characterising materials, such as polyethylene naphthalate (PEN) and tetraphenyl butadiene (TPB), in terms of their wavelength-shifting efficiency. Preliminary results obtained with the system are consistent with the ones reported in literature: 0.5±0.05 in terms of WLS efficiency (PEN/TPB). A value of 1.24 μs was obtained for the triplet lifetime in Ar, which is a factor of 2.6 smaller than the one described in literature due to the presence of impurities. Further extensions of the system are currently being studied. The foreseen upgrades are expected to allow the study of GEM-like structures potentially interesting for rare-event searches. The design of the setup will be addressed along with the first results.

Nanosecond Partial Discharge Current Waveforms with Polyethylene Naphthalate Films on IEC(b) Electrode

The polyethylene naphthalate (PEN) film has been widely applied as a heat‐resistant thin insulation film and sensor film. For the safe and long application of the film in various products, one significant characteristic is the partial discharge (PD) resistivity. In this study, a well‐known IEC(b) electrode is used to measure PD characteristics such as the maximum partial discharge, qmax and fast PD current waveforms at AC peak voltages of 1–3 kVp and 50–1000 Hz over PEN films with thicknesses of 75, 50, or 25 μm. All experiments are conducted at room temperature of ~20 °C. The positive PD current is defined as the current flowing from a high‐voltage electrode to a ground electrode. The positive and negative qmax increased rapidly with the applied voltage increase but remained almost the same for the applied voltage frequency changes. The PD current duration time was less than 40 ns for the positive current and 30 ns for the negative current at all voltages, frequencies, and film thicknesses. It was deduced that the positive current peak magnitude was approximately twice of the negative one at all applied voltages, frequencies, and film thicknesses. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.