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This study investigated the mechanical and sensing properties of ethylene-vinyl acetate (EVA)/carbon nanotubes (CNTs) composites in both film and fiber forms. The incorporation of aligned CNTs in the composite fibers possess improved mechanical properties and enhanced sensing performance compared to those of composite films with randomly dispersed CNTs. Thermogravimetric analysis revealed promising thermal stability, indicating potential applications for long-term usage. Cyclic tensile testing demonstrated that the fiber samples with better CNT alignment exhibit higher sensitivity, emphasizing the significance of CNT orientation in constructing an efficient conductive network for strain sensing. Considering the contribution of the CNTs' orientation along the measuring direction, a model contains modification parameters was proposed, where a master curve was given, revealing the ideal potential of the EVA/CNTs composite fiber with perfectly aligned CNTs. This work provides valuable insights into the influence of CNT alignment on the mechanical and sensing properties of EVA/CNTs composites. The results underscore the importance of optimizing CNT orientation for enhanced sensing performance in various engineering applications. [ABSTRACT FROM AUTHOR]

The unregulated metallic deposition and continuous cracking of the fragile solid electrolyte interphase are considered the critical barriers that compromise the cyclability of lithium metal batteries (LMB), especially under low N/P ratio (<3) pairing modes. Herein, an ultra‐thin (5 µm), lightweight (0.25 mg cm−2), and moisture‐proof interfacial layer composed of the high‐entropy alloys (denoted as HEAs) and interweaved carbon nanotubes (CNTs) scaffold is constructed to modify the current collector, moreover, the thermally‐induced Li22Si5 alloy blended with the hydrophobic ethylene‐vinyl acetate copolymer (EVA) is infiltrated into the scaffold pores as the moisture‐proof cation reservoir. The HEA@CNT/Li22Si5@EVA interfacial layer not only maximizes the Li‐utilization degree with minimal voltage divergence in symmetric cells but also compensates for irreversible Li depletion in the pouch‐format anode‐less models. As the HEA@CNT/Li22Si5@EVA‐Cu substrate paired with the LiNi0.8Mn0.1Co0.1O2 cathode in a 200 mAh prototype, the phase evolution of oxide cathode and efficient Li utilization at the anode substrate can be real‐time monitored by the transmission‐mode operando X‐ray diffraction. This interfacial layer strategy affords multifunctionality to enable the LMB prototyping without excessive Li abuse. Consequently, cycling endurance and the balanced energy densities (420.1 Wh kg−1) are obtained on the whole cell. [ABSTRACT FROM AUTHOR]

The degradation behaviors of the encapsulant and the imbedded additives significantly determine the reliability of solar modules. Nevertheless, a link between the degradation of the encapsulant, including the additive interactions, and the longevity of the overall module is rarely established until now. Herein, mini‐modules containing ethylene‐vinyl acetate copolymer (EVA) as encapsulant are subject to damp heat (DH) or ultraviolet (UV) weathering based on IEC 61215. Macroscopically, the degradation under both weathering types characterized by I–V measurements and electroluminescence (EL) measurements is diverging in dependence on the used stressor. Using electron paramagnetic resonance and orbitrap mass spectrometry, it is shown that deacetylation of the EVA occurs significantly for both types of weathering. In the case of DH, however, the mechanism of action of the UV stabilizer is hindered, so that strong encapsulant degradation is observed despite a lower energy input in comparison with UV. Furthermore, the produced acetic acid under DH weathering leads to the observed reduction in EL, an increase in series resistance, and, a reduction of the performance of the modules. The work carried out shows that the degradation of the solar modules is strongly dependent on the behavior of the UV stabilizer. [ABSTRACT FROM AUTHOR]

The type of matrix resin of the semi‐conductive shielding layer directly affects the thermal aging characteristics of the semi‐conductive shielding layer and the high‐voltage cable. In this paper, ethylene vinyl acetate (EVA), ethylene ethyl acrylate (EEA), and ethylene butyl acrylate (EBA) resins were used as matrix to prepare carbon black (CB) + EVA, CB + EEA, and CB + EBA shielding materials. The law of physicochemical, electrical, and mechanical properties of different matrix resin shielding materials with aging time was studied, and the influence mechanism of matrix resin on the aging characteristics of shielding materials was analyzed. The results show: with the increase of aging time, the crystallization area and the number of functional groups of the three shielding materials decreased to varying degrees. The number of functional groups in CB + EBA shielding materials decreased evenly with aging time, but that of CB + EVA and CB + EEA shielding materials changed significantly after 7 days of aging. After 60 days of aging, the crystallization area of CB + EBA shielding material changed slightly, but that of CB + EVA and CB + EEA shielding material decrease significantly. The electrical properties of the three shielding materials showed different decreasing trend with aging time. When the aging time is 7 days, the positive temperature coefficient (PTC) effect of CB + EEA shielding material decreases obviously. When the aging time is 30 days, the resistivity of CB + EVA and CB + EEA shielding material increases slowly (9 Ω cm–12 Ω cm) with the increase of temperature. When the aging time is 60 days, the resistivity of CB + EBA shielding material decreases obviously, and the PTC effect weakens obviously. Taking the mechanical properties of the shielding material as reference, the rapid deterioration stage of the mechanical properties of the three shielding materials is different. The CB + EVA and CB + EEA shielding material rapid deterioration time is 0–7 days, and the tensile strength and elongation of the shielding material are greatly reduced. The rapid deterioration stage of CB + EBA shielding material is 7–30 days, and the tensile strength and elongation decrease from 24.38 MPa and 499.5% to 14 MPa and 155.7%, respectively. This work can provide data support for the selection of matrix resin of shielding material and the fault analysis of shielding layer of high voltage cable. [ABSTRACT FROM AUTHOR]

Lithium‐sulfur batteries utilizing sulfide solid electrolytes hold considerable potential for achieving both high energy density and enhanced safety. However, the substantial volume changes experienced by sulfur during cycling result in mechanical stress accumulation, leading to mechanical degradation and thereby degrading overall electrochemical performance. In this study, a stress‐buffer strategy is proposed to address this challenge by engineering a mechanically resilient crosslinked structure for the composite sulfur cathode. This structure is accomplished through the integration of a highly flexible thermoplastic elastomer (ethylene vinyl acetate, EVA), which enables stress release during sulfur volume variations by the repeated stretching and shrinking of EVA, thereby maintaining stable ionic/electronic diffusion channels within the electrode. By virtue of the mechanically stable architecture, the stress evolution experienced by the entire sulfur electrode is substantially reduced, witnessing a remarkable decrease of ≈33.7%. Consequently, the S‐EVA composite cathode demonstrates exceptional electrochemical performance, especially cycling stability. Notably, the S‐EVA composite cathode, with a high loading of 7.5 mg cm−2, exhibits stable cycling performance close to 3.0 mAh cm−2 within 50 cycles. This work not only offers novel insights into mitigating the mechanical stress within the electrode but also paves the way for developing durable high‐performance all‐solid‐state batteries. [ABSTRACT FROM AUTHOR]

Introduction: The choice of materials for covering plantar orthoses or wearable insoles is often based on their hardness, breathability, and moisture absorption capacity, although more due to professional preference than clear scientific criteria. An analysis of the thermal response to the use of these materials would provide information about their behavior; hence, the objective of this study was to assess the temperature of three lining materials with different characteristics. Materials and Methods: The temperature of three materials for covering plantar orthoses was analyzed in a sample of 36 subjects (15 men and 21 women, aged 24.6 ± 8.2 years, mass 67.1 ± 13.6 kg, and height 1.7 ± 0.09 m). Temperature was measured before and after 3 h of use in clinical activities, using a polyethylene foam copolymer (PE), ethylene vinyl acetate (EVA), and PE-EVA copolymer foam insole with the use of a FLIR E60BX thermal camera. Results: In the PE copolymer (material 1), temperature increases between 1.07 and 1.85 °C were found after activity, with these differences being statistically significant in all regions of interest (p < 0.001), except for the first toe (0.36 °C, p = 0.170). In the EVA foam (material 2) and the expansive foam of the PE-EVA copolymer (material 3), the temperatures were also significantly higher in all analyzed areas (p < 0.001), ranging between 1.49 and 2.73 °C for EVA and 0.58 and 2.16 °C for PE-EVA. The PE copolymer experienced lower overall overheating, and the area of the fifth metatarsal head underwent the greatest temperature increase, regardless of the material analyzed. Conclusions: PE foam lining materials, with lower density or an open-cell structure, would be preferred for controlling temperature rise in the lining/footbed interface and providing better thermal comfort for users. The area of the first toe was found to be the least overheated, while the fifth metatarsal head increased the most in temperature. This should be considered in the design of new wearables to avoid excessive temperatures due to the lining materials. [ABSTRACT FROM AUTHOR]

The study focusses on a low‐density polyethylene/isotactic polybutene‐1 peel system with low‐density polyethylene as matrix and isotactic polybutene‐1 as peel component sealed against itself (cohesive peel system), and on an ethylene vinyl acetate/linear low‐density polyethylene peel system with ethylene vinyl acetate as matrix and linear low‐density polyethylene as peel component sealed against polyethylene terephthalate (adhesive peel system). Due to a new approach to estimate the true fracture surface using 3D reconstruction, it was possible to determine the true adhesive energy release rate, especially for cohesive peel systems. This enables a direct comparison of the fracture mechanics parameters determined from both types of peel systems. The results reveal that the recipe has a distinct influence on the peel behavior. An increasing amount of the used peel component leads in any case to a decrease of the peel force as well as of the energy release rate for both, sealed adhesive and cohesive peel systems. Using application engineering examples generalizable relationships between structure and properties of peel systems could be estimated and the structure sensitivity of the fracture mechanical parameters could be proven. [ABSTRACT FROM AUTHOR]

In this work, self-reinforced composite of recycled polyester (rPET) fibers/recycled poly (ethylene terephthalateco-1,4-cylclohexy-lenedimethylene terephthalate) (rPETG) was prepared by internal mixing and molding press, in which rPET fibers were modified according to the previous method. The effects of compatibilizers including polyethylene-octene grafting glycidyl methacrylate (POE-g-GMA) and ethylene vinyl acetate grafting maleic anhydride (EVA-g-MAH) on the toughness of the composites were studied, respectively. The results showed that POE-g-GMA had better toughening effect on composite than EVA-g-MAH, the POE-g-GMA not only increased the toughness of rPET fibers/rPETG composite but also maintained the strength of composite at a high level. The impact strength of modified rPET fibers/POE-g-GMA/rPETG composite was found to increase by 910%. And, the bending strength and tensile strength were improved by 34.7% and 22.2%, respectively. DSC and SEM results indicated that with an increase in POE-g-GMA content, the degree of crystallinity of rPET fibers/POE-g-GMA/rPETG decreased, bonding between the fibers and matrix became tight, which improved the stress transfer ability between the matrix and the fibers. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to investigate the performance of bio-based lubricants (BBL), namely, palm mid-olein (PMO) enriched with an antioxidant agent, tertiary-butylhydroquinone (TBHQ) and a viscosity improver, ethylene-vinyl acetate (EVA), in journal bearing (JB) applications. Design/methodology/approach: Samples of the BBL were prepared by blending it with TBHQ and EVA at various blending ratios. The oxidative stability (OS) and viscosity of the BBL samples were examined using differential scanning calorimetry and a viscometer, respectively. Meanwhile, their performance in JB applications was evaluated through the use of a JB test rig with a 0.5 length-to-diameter ratio at various operating conditions. Findings: It was found that the combination of PMO + TBHQ + EVA demonstrated a superior oil film pressure and load-carrying capacity, resulting in a reduced friction coefficient and a smaller attitude angle compared to the use of only PMO or VG68. However, it was observed that the addition of TBHQ and EVA to the PMO did not have a significant impact on the minimum oil film thickness. Practical implications: The results would be quite useful for researchers generally and designers of bearings in particular. Originality/value: This study used PMO as the base stock, and its compatibility with TBHQ and EVA was investigated in terms of its OS and viscosity. The performance of this treated BBL was evaluated in a hydrodynamic JB. Peer review: The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-11-2023-0363/ [ABSTRACT FROM AUTHOR]

There is a growing need for a mouthguard sheet material with higher shock absorption and dispersion capacity than those obtained by conventional materials. A five-layer mouthguard sheet material was previously developed using laminated ethylene vinyl acetate and polyolefin copolymer resin. In this study, the shock absorption capacity and dispersion capability of the new sheet material were investigated and compared with those of other materials. Impact testing for the new sheet material showed that the force required to displace the sheet by 1 mm was significantly higher at all thicknesses (p<0.001), whereas the puncture energy and displacement were significantly lower than those for ethylene vinyl acetate (p<0.05). The five-layer mouthguard sheet material successfully absorbed and resisted shock. Therefore, the sheet material potentially increases resistance to applied deformation in teeth and alveolar bone and maintains structure. The five-layer sheet material could expand the range of mouthguard products and help prevent oral trauma. [ABSTRACT FROM AUTHOR]

Electromagnetic shielding plastics with different mass fractions were prepared by melt blending three kinds of silver-coated copper powder (Ag@Cu) with ethylene-vinyl acetate copolymer (EVA). The effects of different mass fractions and particle sizes of Ag@Cu on the electrical conductivity, shielding properties and mechanical properties of EVA-based electromagnetic shielding plastics were investigated. EVA-based electromagnetic shielding plastics were toughened by maleic anhydride grafted ethylene-octene copolymer/ethylene-octene copolymer (POE-g-MAH/POE) toughening masterbatch and polyisobutylene (PIB)/terpene toughening masterbatch, respectively, to obtain highly filled electromagnetic shielding plastics. The results show that with the increase of Ag@Cu content, the electrical conductivity of EVA-based electromagnetic shielding plastics increases, while the mechanical properties decrease. The percolation threshold of the composites decreases with the increase of filler particle size. When the Ag@Cu filling content is 80%, the shielding effectiveness increases with the increase of filling particle size. Compared with POE-g-MAH/POE, the toughening effect of PIB/terpene is the best, the elongation at break is increased to 187.3%, the shielding effectiveness is kept above 70 dB in the range of 30~1 000 MHz, and it shows better extrusion processability. [ABSTRACT FROM AUTHOR]

Potential‐induced degradation (PID) may be a serious concern in photovoltaic (PV) modules and plants, particularly when approaching high system voltages (1500+ V). Here, we investigate PID occurring in bifacial rear‐emitter silicon heterojunction (SHJ) solar cells encapsulated in a glass/glass (G/G) module configuration with ethylene vinyl acetate (EVA) as an encapsulant. PID testing was performed at 85°C in 85% relative humidity (RH), and the solar cells were subjected to −1 kV and +1 kV for up to 800 h. SHJ cells were found to degrade when subjected to −1 kV, and to a lesser extent when left unbiased in damp heat (DH) conditions, while the application of +1 kV prevented degradation. Although prone to PID after extended test durations, the SHJ mini‐modules investigated in this study noticeably passed the industry standard (IEC 61215:2021) PID test of 96 h. The degradation was primarily characterized by losses in short‐circuit current (ISC) at the front side, followed by fill factor (FF) and open‐circuit voltage (VOC). A cross‐sectional transmission electronic microscopy analysis of the laminates subjected to −1 kV highlighted a transport of sodium (Na) through the transparent conductive oxide (TCO), reaching the amorphous Si/TCO interface. The samples tested in DH conditions and with positive PID test conditions did not exhibit such a migration of Na. To account for these observations, we updated a previously proposed model describing the sensitivity of SHJ cells to water. In our degradation model, moisture in the module corrodes the glass, creating sodium hydroxide (NaOH) that then percolate through the EVA before reaching the SHJ cell. The application of a high negative bias amplifies the previous mechanism by increasing the availability of Na+ and also enhances the drift of Na+ through the EVA to the cell. Finally, we demonstrate that PID can be mitigated or suppressed at the module level by using a high‐volume resistivity encapsulant with a low water vapor transmission rate (WVTR) or by encapsulating SHJ solar cells in a configuration impermeable to water (e.g., using an edge sealant). [ABSTRACT FROM AUTHOR]

This paper proposes a novel design for a frequency reconfigurable and bandwidth-enhanced antenna for use in biomedical telemetry applications. Data pertaining to a patient’s body parameters, such as blood pressure, pulse, and temperature, are gathered using sensors and then transmitted to a remote place for monitoring. The proposed antenna is connected to a wearable transmitter, which transfers the body parameter data to a centrally located nearby control unit. The antenna operates in the 5.8 GHz band in single-band mode and in the 4.27 GHz (C band) and 5.8 GHz industrial, scientific, and medical (ISM) bands in dual-band mode. The use of ethylene-vinyl acetate foam as a substrate makes the structure waterproof and ultraviolet resistant. The basic antenna structure equipped with proximity coupling offers a front-to-back ratio (FBR) of 17.62 dB and a bandwidth of 122 MHz. With an additional upper patch and resonant slots, bandwidth enhancement of 82.85% and 11.57% improvement in the FBR are achieved, respectively. Overall, a maximum FBR of 19.66 dB and gain of 5.0 dBi are attained over the resonant frequency. The specific absorption rate is found to be 0.145 W/kg for 10 gram of tissue. [ABSTRACT FROM AUTHOR]

Ethylene vinyl acetate (EVA) copolymers are widely employed as pour point depressants to enhance the flow properties of crude oil. However, EVA copolymers have limitations that necessitate their development. This work investigated the modification of EVA via gamma radiation-induced grafting of butyl acrylate (BuA) monomers and the evaluation of grafted EVA as a pour point depressant for crude oil. The successful grafting of poly(butyl acrylate) p(BuA) onto EVA was verified through grafting parameters, FTIR spectroscopy, and 1H NMR spectroscopy. Treating crude oil with 3000 ppm of (EVA)0kGy, (EVA)50kGy, and (1EVA:3BuA)50kGy yielded substantial reductions in pour point of 24, 21, and 21 °C, respectively. Also, rheological characterization demonstrated improving evidenced by a viscosity reduction of 76.20%, 67.70%, and 71.94% at 25 °C, and 83.16%, 74.98%, and 81.53% at 12 °C. At low dosages of 1000 ppm, the EVA-g-p(BuA) exhibited superior pour point reductions compared to unmodified EVA, highlighting the benefit of incorporating p(BuA) side chains. The grafted EVA copolymers with p(BuA) side chains showed excellent potential as crude oil flow improvers by promoting more effective adsorption and co-crystallization with paraffin wax molecules. [ABSTRACT FROM AUTHOR]

In this study, the miscibility of ethylene vinyl acetate/olefin block copolymer (EVA/OBC) blends was investigated through the determination of melt-state viscoelastic properties as well as by morphological analysis using experimental and theoretical approaches. The SEM micrographs showed droplet-matrix morphology, and the blend containing a higher content of OBC exhibited the highest OBC-dispersed phase domain size. The complex viscosity of EVA/OBC blends showed a positive deviation from the log-additivity rule at all compositions, which indicates the strong interaction between phases. Cole–Cole and Han plots indicated miscibility in the molten state between EVA and OBC. The interfacial tension of EVA/OBC blends was determined by the implementation of Palierne and Bousmina emulsion models. Moreover, the blend samples were characterized in terms of creep properties using a dynamic mechanical analyzer, which demonstrated that the OBC increased the creep strains of the blends. The four-element Burger model and the Findley power law model were employed to model the creep behaviors of the EVA, OBC, and blend samples. The model predictions indicated that the incorporation of OBC into the EVA improved the creep rate of EVA/OBC blends significantly. [ABSTRACT FROM AUTHOR]

The degradation status of polymer encapsulants in photovoltaic (PV) modules with backsheets of various compositions is evaluated by near‐infrared absorption (NIRA) spectroscopy. The method is used to identify backsheet types and to assess the content of carbonyl species in the ethylene vinyl acetate copolymer encapsulant expressed as a carbonyl index (CI). The CI distributions are collected for PV modules of different ages and in different climatic conditions from twelve PV installations in Europe (EU) and South Africa (ZA) and the peak of the index distribution is found to be related exponentially to the total dose of solar irradiation. The CI growth rate with the irradiation dose in EU is around two times larger than in ZA, most probably due to more massive moisture ingress into PV modules installed in a more humid EU climate. For similar total solar exposures, the CI is found to depend on the backsheet structure. Repeated measurements on the same plant after an additional 2 years of module operation confirm the capacity of NIRA spectroscopy to track the temporal progression of encapsulant degradation using CI as a quantifier depending on the encapsulant‐backsheet bill of materials, plant age, and climatic zone. [ABSTRACT FROM AUTHOR]

Background/Aim: Mouthguards are used to prevent dental trauma and orofacial injuries. The aim of this study was to evaluate the influence of ethylene‐vinyl acetate (EVA) aging by thermocycling on elastic modulus, stress, strain and shock absorption ability of different ethylene‐vinyl acetate brands used for mouthguards. Methods: Thirty EVA samples with a dimension of 70 × 10 × 3 mm were obtained from four commercial brands (Bioart®, Erkodent®, Polyshok® and Proform®). Fifteen samples were submitted to 10,000 cycles (5°C–55°C) in a thermocycling machine with an immersion time of 30 s and a transfer time of 5 s. The samples were submitted to a uniaxial tensile test in a universal testing machine to calculate the elastic modulus. Data were statistically evaluated by two‐way ANOVA and Holm‐Sidak test. A three‐dimensional model of the anterior maxilla was created using Rhinoceros 5.0. A 3 mm custom‐fitted mouthguard was simulated. The three‐dimensional volumetric mesh was generated using the Patran software (MSC Software) with isoparametrics, 4‐noded tetrahedral elements and exported to Marc/Mentat (MSC Software) as element number 134. A non‐linear dynamic impact analysis was performed in which a rigid object struck the central incisor at a speed of 5 m/s. The stresses were evaluated by the modified von Mises criteria and the strains were also recorded. Results: Statistically significant differences were observed for elastic modulus values (p <.001). Mean and standard deviation values (MPa) without thermocycling were: Bioart (34.5 ± 0.9), Erkodent (15.0 ± 0.4), Polyshok (17.3 ± 0.4), Proform: (20.6 ± 0.8); and with thermocycling: Bioart (25.4 ± 0.8), Erkodent (10.7 ± 0.5), Polyshok (13.3 ± 0.6), Proform (13.1 ± 0.6). The thermocycling process reduced stress and strain levels regardless of the mouthguard materials. Shock absorption ability calculated based on the strain values was increased with thermocycling process. Conclusion: The thermocycling process, regardless of the commercial brand, reduced the stress/strain and increased the shock absorption ability of mouthguards. [ABSTRACT FROM AUTHOR]

Mastitis is an infectious disease condition resulting in inflammatory reaction which occurs when a large number of leukocytes migrate into the mammary gland. Mastitis causes significant financial losses for the global dairy industry. The present study aimed at development of transdermal film comprising of Azadirachta indica extract for treatment of mastitis, which is economical, safe and will not emerge multidrug resistance amongst pathogens. Azadirachta indica extract was prepared by sonication method. The extract was evaluated for minimum inhibitory concentration against gram-positive and gram-negative organisms. Transdermal films with Azadirachta indica extract were prepared with ethylene vinyl acetate and polyvinyl acetate then subjected for the physical characterization, drug content, In vitro dissolution, tensile strength and antibacterial activity. The minimum inhibitory concentration of extract displayed 5mg/ml. Based on quantification of azadirachtin by UV spectrophotometer 100 mg of extract was incorporated in each transdermal film. Transdermal films of Azadirachta indica extract possessed desirable physical properties, and exhibited the drug release of 91.54% in 8 hours. Transdermal film of Azadirachta indica showed sensitivity with a zone of inhibition of 19mm, 16mm, 19mm and 22mm against Staphylococcus aureus, Escherichia coli, Bacillus subtilis and Pseudomonas aeruginosa respectively. Data obtained revealed that transdermal films of Azadirachta indica extract exhibited good drug release profile and desirable physical properties, with good antibacterial activity. The present work reveals that transdermal film of Azadirachta indica extract can be considered for the treatment of mastitis. [ABSTRACT FROM AUTHOR]

The overactive bladder is a condition characterized by a sudden urge to urinate, even with small volumes of urine present in the bladder. The current treatments available for this pathology consist on conservative approaches and the continuous administration of drugs, which when made by conventional methods has limitations related to the first pass metabolism, bioavailability, severe side effects, and low patient adherence to treatments, ultimately leading to low effectiveness. Within this context, the present work proposes the design, manufacture, and characterization of an intravesical implant for the treatment of overactive bladder pathology, using EVA copolymer as a matrix and oxybutynin as a drug. The fabrication of devices through two manufacturing techniques (extrusion and additive manufacturing by fused filament fabrication, FFF) and the evaluation of the implants through characterization tests was proposed. The usability and functionality were evaluated through simulated insertion of the device/prototype in a bladder model through catheter insertion tests. The safety and effectiveness of the devices was investigated from mechanical testing as well as drug release assays. Drug release assays presented a burst release in the first 24 h, followed by a release of 1.8 and 2.8 mg/d, totalizing 32 d. Mechanical tests demonstrated an increase in the stiffness of the specimens due to the addition of the drug, showing a change in maximum stress and strain at break. The released dose was higher than that usually presented when considering the oral administration route, showing the optimization of the development of this implant has the potential to improve the quality of life of patients with overactive bladder. [ABSTRACT FROM AUTHOR]

The improvement of down-shifting solar cells through reducing the reflection in short wavelength range by scattering is investigated experimentally and theoretically. Such down-shifting solar cells are fabricated by doping Y2O3 particles into down-shifting ethylene vinyl acetate films with CaAlSiN3:Eu2+ phosphors. Experimental results show that the scattering of Y2O3 particles can reduce the reflection of the down-shifting solar cells in the wavelength below 450 nm. It can be attributed to two reasons. The first is that the backscattering in the short wavelength is weaker than that in the middle and long wavelength. The second is that the scattering by Y2O3 particles allows more light reach the phosphors and increases their absorption. This means that more photons with poor spectral responses can be converted into the photons with better spectral responses. This work provides a way to realize simultaneously strengthening the down-shifting effect and suppressing the phosphor-induced reflection and can be used to further improve the down-shifting solar cells. [ABSTRACT FROM AUTHOR]

Protective coating is one of the effective ways to help concrete structures resist environmental erosion. However, most of the existing coating materials are organic compounds, which have the disadvantages of poor durability and high energy consumption. In this study, metakaolin with excellent durability was used as the main raw material, and a flexible and waterproof ethylene‐vinyl acetate emulsion was added to improve the high brittleness characteristics of metakaolin, resulting in a metakaolin‐based geopolymer coating material. Through tests such as water absorption, hardness, gloss, and tensile properties, we investigated the effects of the powder–liquid ratio and the type and amount of admixture on the properties of the coating. The results show that the coating exhibits better performance when the powder‐to‐liquid ratio is 0.6. Based on this, it was found that the optimal dosage of water‐reducing agent, coupling agent, and defoamer was 0.7%, 0.3%, and 0.3%, respectively. [ABSTRACT FROM AUTHOR]

The mechanical analysis of photovoltaics and building integrated photovoltaics is a key step for their optimal design and certification, and requires careful consideration, alongside solar power, durability and functionality issues. The solar cells are encapsulated in thin interlayers that are usually composed of a viscoelastic Ethylene–Vinyl Acetate compound, and protected by thin glass and/or plastic layers. This paper investigates the out-of-plane bending response of a full-scale commercial PV module and focuses attention on the shear bonding efficiency of the thin encapsulant for quasi-static and dynamic mechanical considerations. The parametric analytical analysis, carried out in this study for a laminated glass plate, highlights the possible consequences of the viscoelastic shear coupling on the cross-section load-bearing demand in the covers. As a direct effect of severe operational conditions (i.e., ageing, non-uniform/cyclic thermal gradients, humidity, extreme mechanical/thermal loads, etc.) the shear rigidity and adhesion of these films can suffer from repeated/progressive modification and even degradation, and thus induce major stress and deflection effects in the out-of-plane mechanical response of the PV module components. The minimum shear bond efficiency required to prevent mechanical issues is calculated for various configurations of technical interest. Accordingly, it is shown how the quasi-static and dynamic mechanical performance of the system modifies as a function of a more rigid or weak shear coupling. [ABSTRACT FROM AUTHOR]

Recent explosions and impact events have highlighted the exposure of civil structures, prompting the need for resilient new constructions and retrofitting of existing ones. Laminated glass panels, particularly in glazed facades, are increasingly used to enhance blast resistance. However, the understanding of glass fragments and their interaction with the interlayer is still incomplete. This paper investigates experimentally the quasi-static and dynamic responses of cured and uncured polymers for seven different materials—two different products of polyvinyl butyral (PVB), two ethylene vinyl acetate products (EVA), one product of thermoplastic polyurethane (TPU), and two SentryGlas products (SG)—that were tested between 21 and 32 °C (69.8 and 89.6 °F), which is the recommended room temperature. In these experiments, the responses of PVB, EVA, TPU, and SG were evaluated under a quasi-static strain rate of 0.033 s−1 and compared to the results under a relatively higher strain rate of 2 s−1. Moreover, the high strain rate loading of the materials was accomplished using a drop-weight testing appliance to evaluate the engineering stress–strain response under strain rates between 20 and 50 s−1. The results demonstrated that with strain rates of 20 s−1, PVB behaved like a material with viscoelastic characteristics, but at 45 s−1 strain rates, PVB became a non-elastic material. SG, on the other hand, offered both a high stiffness and a high level of transparency, making it a very good alternative to PVB in structural applications. In contrast, after the maximum stress point, the response to the failure of the seven materials differed significantly. The tests provided ample information for evaluating alternative approaches to modeling these different materials in blast events. [ABSTRACT FROM AUTHOR]

[Display omitted] • LIBS analysis enabled the identification of fluorine-containing polymers in waste. • LIBS analysis enabled determination of elemental composition of recovered materials. • Contact angle and color analysis were used to monitor surface of recovered materials. • Distribution of heat within the panels during heating can be facilitated by busbars. The study presents an innovative approach to the analysis of waste silicon photovoltaic panels prior and after thermal treatment. Using laser-induced breakdown spectroscopy (LIBS), the elemental composition of multilayered panel backsheets was determined, identifying a TiO 2 -containing coating laminate, a polyvinylidene fluoride (PVDF) layer, and an ethylene vinyl acetate (EVA) encapsulant, while also estimating their thickness. Identifying the fluorine-containing layers allowed their selective removal and safe processing of the used panels. Thermal processing parameters such as temperature (400–550 °C), time (5 – 60 min) and orientation of the busbar relative to the heat source were optimized based on contact angle measurements and CIELAB color space analysis, techniques used to detect organic residues in recovered glass and silicone. The decomposition process was examined by thermal analysis coupled with mass spectroscopy, which revealed that there were no volatile fluorine compounds in the gases released, although fluorine was detected on the recovered glass surface by SEM – EDS examination. After the PVDF layer was removed, fluorine compounds were not found in volatile gases or on the surface of recovered inorganic materials. The study indicated that the orientation of the busbars facilitates the decomposition of organic matter. Methods for reusing recovered secondary materials were also provided, suggesting the potential applications and benefits of recycling components from silicon photovoltaic panels. [ABSTRACT FROM AUTHOR]

• Scrapped PV panels are recovered comprehensively. • Leaching efficiency of Ag is over 96% by HNO 3. • The impurities in solar cells are removed efficiently. • Cu strips are purified and recovered by replacement reaction. • The proposed method for PV panels recycling is profitable. The increasing scrapped Si-based photovoltaic (PV) panels has become an urgent problem, and their disposal is essential for resources utilization and environment issues. This paper proposes a comprehensive process for recycling of discarded silicon-based PV panels economically, environmentally, and efficiently. Based on the thermal properties of ethylene vinyl acetate (EVA), they are removed from the discarded PV panels at 600 °C with heating rate of 5 °C/min and maintain for one hour. The glass, solar cells, and copper strips were separated after heat treatment. Simultaneously, the solar cells were crushed into powder. Nitric acid was used to recover silver from the solar cell powder, while most of the metal impurities such as Mg, Ti and Al, were removed as well. The leaching efficiency of silver was over 96 % under the optimized conditions: HNO 3 of 4.0 mol/L, liquid-to-solid ratio of 10:1, temperature of 50 °C for 80 min. Regarding the copper strips, they were sequentially treated with 0.5 mol/L CH 3 COOH and NaOH solution to remove the oxides of Pb and Sn on their surface. Subsequently, they were placed into the solution of 1.0 mol/L CuSO 4 with pH of 2 ∼ 3 to eliminate Pb and Sn. This article provides significant reference for the recycling of Si-based PV panels. [ABSTRACT FROM AUTHOR]

This document is a collection of patents related to elastomers and plastics. The patents cover a wide range of topics, including modified rubbers, materials for shielding from radiation, coated rubber compositions, foams, reinforcement agents, molecular composites, polyethylene compositions, low-molecular-weight polytetrafluoroethylene, EVA foam compositions, carbon fiber compositions, NBR compositions, plastic composites, electrically conductive polymer composites, and polyester recycling processes. [Extracted from the article]

The present investigation mainly aimed at analyzing the rutting responses of polymer-modified binders with and without Polyphosphoric Acid (PPA) and by considering increased loading times in the Multiple Stress Creep and Recovery (MSCR) tests. Typical high pavement temperatures of 52, 58 and 64 °C were chosen, and these loading times varied from 1.0 to 8.0 s (1/9, 2/9, 4/9 and 8/9 s). Formulations with styrene–butadiene–styrene copolymer—SBS (AC + SBS and AC + SBS + PPA), ethylene vinyl acetate copolymer—EVA (AC + EVA and AC + EVA + PPA) and Elvaloy® terpolymer (AC + Elvaloy + PPA) were prepared, and the high PG grade of all these formulations was controlled at 76-XX. In general, the AC + Elvaloy + PPA was the best formulation to counteract rutting at longer creep times—especially 4/9 and 8/9 s—due to the presence of a strong and stable polymer network within the binder matrix. Moreover, the AC + SBS + PPA was able to deal with traffic levels similar or slightly higher than those of the AC + SBS, and this might be attributed to the hardness imparted by PPA modification and the presence of more stable polymer networks in the AC + SBS + PPA. On the other hand, the AC + EVA + PPA was found to be less rut resistant than the AC + EVA, and none of the EVA-modified binders depicted sufficient degrees of stiffness to deal with heavier and slow-moving traffic levels—mainly for temperatures of 58 °C or higher and loading times of 4/9 s or longer. Overall, the data indicate that binders with high degrees of stiffness at standardized MSCR loading conditions (1/9 s) do not necessarily perform well at longer creep times. [ABSTRACT FROM AUTHOR]

Salivary turbidity is a promising indicator for evaluating oral hygiene. This study proposed a wearable mouthguard-type sensor for continuous and unconstrained measurement of salivary turbidity. The sensor evaluated turbidity by measuring the light transmittance of saliva with an LED and a phototransistor sealed inside a double-layered mouthguard. The sensor was also embedded with a Bluetooth wireless module, enabling the wireless measurement of turbidity. The mouthguard materials (polyethylene terephthalate-glycol and ethylene-vinyl acetate) and the wavelength of the LED (405 nm) were experimentally determined to achieve high sensitivity in salivary turbidity measurement. The turbidity quantification characteristic of the proposed sensor was evaluated using a turbidity standard solution, and the sensor was capable of turbidity quantification over a wide dynamic range of 1–4000 FTU (formazine turbidity unit), including reported salivary turbidity (400–800 FTU). In vitro turbidity measurement using a saliva sample showed 553 FTU, which is equivalent to the same sample measured with a spectrophotometer (576 FTU). Moreover, in vivo experiments also showed results equivalent to that measured with a spectrophotometer, and wireless measurement of salivary turbidity was realized using the mouthguard-type sensor. Based on these results, the proposed mouthguard-type sensor has promising potential for the unconstrained continuous evaluation of oral hygiene. [ABSTRACT FROM AUTHOR]

Although gypsum plaster has been well studied, there are few related researches on the effects of primers on the pull-off strength of gypsum plaster in the plastering systems. Therefore, the effects of no primer, vinyl acetate ethylene (VAE)-type primers, styrene-acrylic (SA)-type primers, and acetate-acrylic (AA)-type primers on the pull-off strength of gypsum plaster, were comparatively discussed. The results indicated that these primers all can chemically bond with the gypsum plaster and aerated concrete substrate, thus the adhesion of gypsum plaster on the substrate was promoted, and the failure type in the pull-off strength test changed from adhesive failure to cohesive failure. With the better permeability of primers and the lower degree of the pore blocking, the negative impacts on the gypsum dihydrate crystals were smaller, the mechanical interlocking force generated between the substrate and the gypsum plaster was larger, and the damage surface of cohesive failure is further away from the bonding transition area (plaster/primer/substrate). Therefore, the application of VAE-type primers and AA-type primers could increase the pull-off strength of gypsum plaster by 1.74–2.44 times and 1.70–1.90 times, respectively, while the application of SA-type primers would reduce the pull-off strength of gypsum plaster by at least 30%. [ABSTRACT FROM AUTHOR]

Thermoplastic vulcanizate (TPV) made from the ethylene-vinyl acetate copolymer (EVA)/nitrile rubber (NBR) blend was fabricated using the dynamic vulcanization method. Differential scanning calorimetry (DSC) was utilized to analyze the nonisothermal crystallization kinetics of both pure EVA and EVA/NBR TPV. The nonisothermal crystallization mechanism was evaluated using the Avrami method modified by Jeziorny, the Ozawa method and the Mo method. The results demonstrate that the nonisothermal crystallization of both pure EVA and EVA/NBR TPV can be adequately described by the Avrami method modified by Jeziorny and the Mo method, while the Ozawa method is not applicable. By elevating the cooling rate, there was a reduction in the crystallization temperature and t1/2 for both pure EVA and EVA/NBR TPV, while the degree of crystallization increased. At the same cooling rate, the crystallization temperature of the EVA/NBR TPV was found to be higher than that of the pure EVA, suggesting that the presence of NBR facilitated the nucleation of the EVA matrix within the EVA/NBR TPV. Moreover, a steric hindrance effect existed in the NBR phase of EVA/NBR TPV at the same cooling rate, resulting in a larger t 1/2 compared to that of the pure EVA, indicating hindered crystal growth. [ABSTRACT FROM AUTHOR]

Thermally conductive and flame-retardant polyolefin composites are facing great challenges in meeting the increasing demands for fire safety and thermal management. Aiming at simultaneously enhancing thermal conductivity and flame retardancy, hexagonal boron nitride (hBN) and magnesium hydroxide (MH) were adopted in ethylene–vinyl acetate copolymer/polyolefin elastomer (EVA/POE) blends to design composites with selective filler distributions and co-continuous networks via different processing schemes. The thermal conductivity and flame retardancy show strong dependence on the distributed structure of hBN and MH. The composites with hBN-rich centers and MH-rich edges in the filled POE phase show a thermal conductivity of 0.70 W/(m·K) and an LOI of 27.7%, which are very close to the thermal conductivity of EVA/POE/hBN and the LOI of EVA/POE/MH at the same total filler content. The composites with MH-rich centers and hBN-rich edges show pHRR, THR and TSP values of 169 kW/m2, 49.8 MJ/m2 and 1.8 m2, which are decreased by 40%, 33% and 62% in comparison with EVA/POE/MH, respectively. Modulating the filler structure distribution provides a strategy to co-enhance thermal conductivity and flame retardancy. [ABSTRACT FROM AUTHOR]

This study aimed to compare plantar pressure distribution and muscle frequency between hydrodynamic and typical sports shoes. Twelve healthy adult males participated in this experimental study. The hydrodynamic shoe features an outer sole with a pathway for fluid flow. The typical sports shoe with Ethylene-Vinyl Acetate soles was used for the comparison. Plantar pressure distribution was measured using the Pedar insole system, and the results were analyzed using Pedar-X software. Electrical muscle activity of the Gastrocnemius, Soleus, Palmaris longus, and tibialis anterior were measured using the Myon electromyography system at a 1000Hz sampling rate. Subjects were randomly assigned to wear either hydrodynamic or typical sports shoes and walked through the end of the pathway five times at a self-selected speed. The plantar area was divided into eight regions, and plantar pressure variables were calculated within these areas. The frequency variable includes mean and median frequency, as well as the 99.5th percentile frequency, representing 99.5% of the signal. Additionally, the bandwidth frequency was calculated. Paired t-test was used for statistical comparison (p<0.05). The results indicated considerable pressure reduction in the heel, forefoot, and toe (P<0.05). However, there is no difference in the time and frequency content of muscle activity between conditions. Based on the results, it seems that hydrodynamic shoes could have an important effect on the reduction of plantar pressure without any change in muscle activity during the gait. [ABSTRACT FROM AUTHOR]

Objective: This systematic review examines the efficacy and biocompatibility of orthodontic clear aligner tooth aligners constructed from polyethylene terephthalate glycol (PeT-G), polypropylene (PP), polycarbonate (PC), thermoplastic polyurethanes (TPUs), and ethylene-vinyl acetate (EVA). Materials and Methods: To find relevant papers published through September 2021, PubMed was searched extensively. Randomized clinical trials (RCTs) and observational studies assessing the effectiveness and biocompatibility of the aligner materials were included. Data were extracted independently, and the quality of included research was appraised using relevant procedures. The research variability necessitated a narrative synthesis. Results: Five studies were included for comparison. All materials were biocompatible; however, PeT-G and EVA aligners caused the least tissue irritation. Patients preferred TPU aligners for initial comfort and PeT-G aligners for transparency and endurance. Conclusion: Biocompatible PeT-G, PP, PC, TPU, and EVA tooth aligners fix malocclusions. Aligner materials should be chosen based on patient preferences, treatment goals, and material qualities. For stronger proof, a longer-term study is needed.

This document is an editorial from the Journal of Plastic Film & Sheeting. The editor reflects on the state of the world, including the impact of the Covid pandemic and the environmental issues caused by plastics. The editor also discusses the use of forever chemicals known as PFAS and the need to find alternatives. The editorial touches on the issue of violence and the importance of critical thinking. The document also provides a summary of the articles featured in the current issue, which include topics such as vitrimer nanocomposites, bioplastics, and self-healing polymeric composites. The editorial concludes with a quote about the value of heresies and a bonus quote about the benefits of strategic data collection. [Extracted from the article]

Photovoltaic (PV) modules are highly efficient power generators associated with solar energy. The rapid growth of the PV industry will lead to a sharp increase in the waste generated from PV panels. However, electro-waste can be successfully used as a source of secondary materials. In this study, a unique procedure for recycling PV modules was developed. In the first stage, the aluminum frame and junction box, 18wt%. and 1wt%. of the module, respectively, were removed. The following stage was crucial, involving a mechanical–thermal method to remove the glass, which accounts for 70wt%. As a result, only 11wt%. of the initial mass of the PV was subjected to the next stage of chemical delamination, which reduced the amount of solvent used. Toluene was used to swell the ethylene vinyl acetate, EVA, and allow for the separation of the PV module. The effects of temperature and ultrasound on separation time were investigated. After the separation of silicon cells, metal ribbons, EVA, and the backsheet were obtained. The purity of the polymers was determined by FTIR and elemental analysis. Thermal properties were measured using DSC calorimetry to determine the basic parameters of the material. [ABSTRACT FROM AUTHOR]

This study reports copolymer composition tailored wrapping of carbon nanotubes, leading to a gigantic dielectric permittivity and peculiar nonlinear rheological response in a nonfluoro copolymer/carbon nanotube (CNT) hybrid system. Specifically, we observed a strong interfacial polarization effect in ethylene vinyl acetate (EVAc) copolymer/CNT nanocomposites, resulting in a dielectric permittivity of approximately 4000 at 10 Hz and 450 (dielectric loss <1) at 1 kHz, with only 1% volume fraction of CNTs and 40% vinyl acetate (VAc) content. No such effect was observed in EVAc with 12% VAc. Extensive amplitude oscillatory rheology studies prompted us to propose a novel hook‐wrap‐type mechanism, wherein polar interactions act as hooks and nonpolar segments allow wrapping, depending on the optimal interactions between the CNT and copolymer. Raman spectroscopy, small‐angle x‐ray scattering, and relaxation studies also revealed a significant change in segmental dynamics and mass fractal compactness with a change in the VAc content. This work provides a melt processing‐based scalable route to develop polymer dielectrics while advancing the fundamental understanding of polymer‐CNT interactions and the underlying mechanisms of dielectric behavior in nanocomposites. [ABSTRACT FROM AUTHOR]

[Display omitted] • First generation PV technology competes with new generations, yet dominating. • Global trends for silicon-based PV recycling are overviewed. • Recovered products are utilized as secondary raw material of the PV industry. • Current challenges are underlined with appropriate suggestions. With the rapid deployment of renewable energy using photovoltaic (PV) panels, the sustainable management of decommissioned PV modules has become challenging. Decommissioned modules contain heavy metals, such as copper, cadmium, and lead, and hazardous polymer substances, such as ethylene vinyl acetate, polyethylene terephthalate, and polyvinylidene fluoride, which can pose a serious threat to the environment if disposed in a landfill. In addition, the low concentration value of critical metals, such as silver, indium, and tellurium, can also be lost. In this context, recycling decommissioned PV panels can be useful to resource recovery of valuable metals while lowering environmental stress. However, the lower share of PV modules and the prolonged life of 25–30 years compared to other waste volumes (e.g., electronic waste) hinder the progress in this direction. In contrast, reaching the end-of-life of the deployed first-generation PV panels is creating attraction toward the recycling of decommissioned modules. Henceforth, exploring the commercial viability of PV recycling necessitates a review of the methodologies that have been investigated on a laboratory scale and have the potential to be up-scaled. In this review, the recent trends in various PV-recycling steps, including frame disassembly, delamination, metal extraction, and recovery, are underlined while the associated problems are determined to suggest the required improvements in future technology. Furthermore, the environmental and economic feasibility of a few techniques are discussed to establish the viability of the recycling process. This review contributes to formulating PV waste management strategies and providing future research directions. [ABSTRACT FROM AUTHOR]

Plastic waste is harmful to the environment and takes thousands of years to decompose naturally. Pyrolysis is an effective method of plastic waste management, and the oil obtained from the process can be used as a modifier for bituminous binders. The polymer modification of bitumen is an effective and commonly used method for improving the rheological performance of the binders. The mixing temperatures are considerably elevated after the addition of polymers to the binders. Various pyrolytic oils are used to reduce the mixing and compaction temperatures of the polymer-modified binders (PMBs). This study analyzed the effect of the addition of high-density polyethelene (HDPE) pyro-oil in viscosity graded (VG30), styrene-butadiene-styrene (SBS), and ethylene vinyl acetate (EVA)-modified binders on the mixing temperatures and rheological properties. The concept of rheograms and Carreau–Yasuda (CY) model fitting were used to determine the mixing temperatures. The rheological investigation involved frequency sweep, temperature sweep, steady shear test, and multiple stress creep and recovery tests using a dynamic shear rheometer. The variation of black diagrams was studied for the binders along with the variation in phase angle and complex modulus of the binders. Fourier-transform infrared spectroscopy was used to assess the chemical changes after the modification and aging of the binders. Damping energy characteristics were investigated for the unmodified, polymer-modified, and HDPE pyro-oil–modified bituminous binders. With increasing shear rates from 100 to 10,000 s−1 , the mixing temperatures of the modified binders decreased by about 8°C–16°C. The addition of pyro-oil to the base and polymer-modified binders decreased the percentage rate of increase in carbonyl and sulfoxide indexes, in turn increasing the resistance to aging of the binders. The addition of pyro-oil reduced the mixing temperatures of base and SBS-modified binders, and the rutting performance of SBS-modified binders. This reduction in mixing temperatures and aging will lead to less energy consumption at the mixing plants, and longer service life of pavements. The use of HDPE plastic waste in the form of pyro-oil in flexible pavements will help reduce the amount of plastic waste. The modification of bitumen with pyro-oil will decrease the amount of bitumen used in pavement construction, ultimately reducing the use of nonrenewable crude reserves that are depleting rapidly. The concept of rheograms for evaluating the flow behavior of the modified binders suggested in this study and its application in mixing plants will be beneficial in reducing mixing temperatures at higher shear rates. The use of pyro-oil for the modification of polymer-modified binders will lead to a reduction of mixing temperatures. This will help save energy at the plants. The application of pyro-oil along with polymers will produce aging-resistant, rutting-resistant, and damping-resistant binders, which will lead to stronger and durable pavements for longer service periods. Hence, the analysis in this research will be beneficial for researchers, highway engineers, hot-mix plant owners, pavement designers, and consultants. [ABSTRACT FROM AUTHOR]

In this paper, melt blending process was adopted to add nanocalcined kaolin into flame-retardant grade ethylene vinyl acetate (EVA) copolymer, and thus, flame-retardant ethylene vinyl acetate nano-composite with high insulation property was prepared. The structure, mechanical properties and electrical properties of ethylene vinyl acetate composite were tested and characterized. The results of the tensile test showed that the tensile strength of the composite was reduced and the tensile modulus of the composite was increased after the addition of calcined kaolin; the results of the electrical properties test showed that the breakdown strength first increased and then decreased along with more addition of calcined kaolin, and the dielectric loss first decreased and then increased along with more addition of calcined kaolin, while the volume resistivity showed a continuous rising trend. The results of small-angle X-ray scattering test showed that the addition of calcined kaolin reduced the expansion range of EVA molecular chain, which was the major reason to cause the variation in electrical properties. [ABSTRACT FROM AUTHOR]

It was found that in the region of the percolation threshold, depending on the dominance of one or another conduction mechanism, the temperature dependence of the specific volume resistivity ρ(T) of the polymer composite based on a matrix of ethylene vinyl acetate is significantly transformed. With an increase in the CB content, there is a decrease by several orders of magnitude in the maximum value of the relative resistivity ρ(T)max/ρ20 in its temperature dependence. Peroxide crosslinking of matrix macromolecules leads to a change in the nature of the temperature dependence of resistivity. [ABSTRACT FROM AUTHOR]

Material extrusion is a promising additive manufacturing technique for fabricating high-performance SiC composites with complex structures. In this work, a novel strategy for fabricating SiC composites via material extrusion combined with solvent debinding and gaseous-liquid two step silicon infiltration was developed. The mixture used for material extrusion was composed of an organic binder, such as high-density polyethylene, ethylene vinyl acetate, paraffin wax and a C/SiC inorganic powder. The experimental results revealed that 89 wt% of the soluble components could be removed after debinding at 40 °C for 10 h in kerosene solvent, and the morphology was satisfactory after subsequent thermal debinding. After reactive sintering, the density of the SiC composite reached 3.12 ± 0.02 g/cm3, with a theoretical residual silicon content of 10.13 vol%. The flexural strength and elastic modulus reached the maximum values of 465 ± 35.35 MPa and 425 ± 11.78 GPa, respectively. [ABSTRACT FROM AUTHOR]

Objective: This systematic review examines the efficacy and biocompatibility of orthodontic clear aligner tooth aligners constructed from polyethylene terephthalate glycol (PeT-G), polypropylene (PP), polycarbonate (PC), thermoplastic polyurethanes (TPUs), and ethylene-vinyl acetate (EVA). Materials and Methods: To find relevant papers published through September 2021, PubMed was searched extensively. Randomized clinical trials (RCTs) and observational studies assessing the effectiveness and biocompatibility of the aligner materials were included. Data were extracted independently, and the quality of included research was appraised using relevant procedures. The research variability necessitated a narrative synthesis. Results: Five studies were included for comparison. All materials were biocompatible; however, PeT-G and EVA aligners caused the least tissue irritation. Patients preferred TPU aligners for initial comfort and PeT-G aligners for transparency and endurance. Conclusion: Biocompatible PeT-G, PP, PC, TPU, and EVA tooth aligners fix malocclusions. Aligner materials should be chosen based on patient preferences, treatment goals, and material qualities. For stronger proof, a longer-term study is needed. [ABSTRACT FROM AUTHOR]

As one of the most widely used personal protective equipment (PPE), body armors play an important role in protecting the human body from the high-velocity impact of bullets or projectiles. The body torso and critical organs of the wear may suffer severe behind-armor blunt trauma (BABT) even though the impactor is stopped by the body armor. A type of novel composite material through incorporating shear stiffening gel (STG) into ethylene-vinyl acetate (EVA) foam is developed and used as buffer layers to reduce BABT. In this paper, the protective performance of body armors composed of fabric bulletproof layers and a buffer layer made of foam material is investigated both experimentally and numerically. The effectiveness of STG-modified EVA in damage relief is verified by ballistic tests. In parallel with the experimental study, numerical simulations are conducted by LS-DYNA® to investigate the dynamic response of each component and capture the key mechanical parameters, which are hardly obtained from field tests. To fully describe the material behavior under the transient impact, the selected constitutive models take the failure and strain rate effect into consideration. A good agreement between the experimental observations and numerical results is achieved to prove the validity of the modelling method. The tests and simulations show that the impact-induced deformation on the human body is significantly reduced by using STG-modified EVA as the buffering material. The improvement of protective performance is attributed to better dynamic properties and more outstanding energy absorption capability of the composite foam. [ABSTRACT FROM AUTHOR]

Due to the high brittleness of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), ethylene-vinyl acetate copolymer (EVA) was incorporated to prepare PHBV/EVA blends by melt blending, and the compatibility of the blends was improved by benzoyl peroxide (BPO). The research found that the addition of BPO triggered the production of free radicals in the PHBV and EVA polymers, followed by the recombination of the radicals to form the chemical cross-linking. The resultant PHBV/EVA/BPO blends showed improved mechanical properties and compatibility. At the optimal BPO content (0.5 phr), the elongation at break increased from 1.24% to 4.47%, the impact strength increased from 7.50 kJ/m2 to 17.75 kJ/m2, and the tensile toughness increased from 15.96 MJ/m3 to 70.00 MJ/m3. The gel content of the blends also reached the maximum value (13.88%) at 0.5 phr of BPO addition. This improvement was primarily attributed to interfacial adhesion between PHBV and EVA due to the chemical cross-linking, the hydrogen bonding interactions and the blends chain entanglements. Therefore, this research can improve the poor mechanical properties of PHBV and expand its potential application value. [ABSTRACT FROM AUTHOR]

Reasonable studies on the composite systems containing conductive nanoparticles are very important to manufacture the materials with physico‐mechanical tailor‐made properties. In this work, rheological percolation, gel‐like behavior and electrical properties of multi‐walled carbon nanotubes (MWCNTs) filled ethylene‐co‐vinyl acetate/acrylonitrile‐butadiene copolymer blends containing 0–7 wt% MWCNTs were studied. The Winter‐Chambon criterion validity was evaluated for physical gelation of the system. The rheological and electrical percolation threshold, gel point (Pg), relaxation exponent (n), gel strength (Sg), and the fractal dimension (df) at the gel point were calculated. The formation of physical gel and rheological percolation threshold were both found to occur at 1 wt% MWCNTs concentration. Based on the df value determined, it was revealed that the system behaved similar to the one in which the excluded volume interactions were nearly screened. It was also found that the storage modulus (G′) near the Pg followed a power‐law scaling relationship in the form G′=8257ε1.36 where ε=p−pgpg is the distance from Pg. The electrical conductivity of the nanocomposites increased with the increase in MWCNTs loading after the nanofillers content surpassed a certain value. A schematic model was proposed to demonstrate the variation of electrical conduction with the increase in MWCNTs concentration. The excluded volume and hard‐core models were also employed to estimate the average aspect ratio of the nanofillers embedded in the system. Highlights: Morphology and gel‐like behavior of EVA/NBR/MWCNTs system were studiedWinter‐Chambon criterion was found to be valid for the gelation of the systemRheological percolation and gel point were occurred at the same MWCNTs loadingIt was found excluded volume interactions were nearly screened at gel pointA schematic model for microstructure development was suggested for the system [ABSTRACT FROM AUTHOR]

The semiconductive layer located between the core and insulation layer of a high-voltage DC (HVDC) cable can inhibit the accumulation of space charge in the insulation layer. This helps increasing the electric field inside the cable, thus improving the stress distribution of the electric field on the inner and outer surfaces of the insulation layer and the electrical strength of the cable. An inevitable positive temperature coefficient effect (PTC) in the semiconductor layer leads to aging failure of the insulation layer. To improve this phenomenon, the semiconductive shielding layer was modified for suppressing its PTC effect and reducing the space charge injection into the insulation layer. Li 1.3 Al 0.3 Ti 1.7 (PO 4) 3 (LATP) was prepared via a solid-phase reaction and added to a composite consisting of carbon black (CB), ethylene vinyl acetate copolymer (EVA), and low-density polyethylene (LDPE). Resistivity, thermally stimulated depolarization current (TSDC), and pulsed electroacoustic (PEA) measurements were performed on the modified sample. The results showed that when the LATP content was 4 wt%, the modification effect of the semiconductive shielding layer was most effective, the PTC effect was reduced by 11%, and the space charge injection into the insulating layer was improved significantly. [ABSTRACT FROM AUTHOR]