Ethylene Vinyl Acetate Research Articles

Green crosslinking strategy for ethylene-vinyl acetate rubber composites with NH2-POSS as a crosslinking agent and reinforcing nanofiller

Ethylene-vinyl acetate rubber is extensively utilized in various fields including electrical wires and cables, automotive, and electronic components. Traditional peroxide vulcanization methods, however, release volatile organic compounds, posing environmental pollution concerns. To address this, 3-amino-polyhedral oligomeric silsesquioxane (NH2-POSS) was synthesized through hydrolytic condensation and used both as a crosslinking agent and a filler in the preparation of ethylene-vinyl acetate-glycidyl methacrylate terpolymer (EVM-GMA) composites. Notably, NH2-POSS not only effectively crosslinks EVM-GMA, but also thus promotes the dispersion of the silica in the composites. EVM-GMA/silica composites crosslinked by NH2-POSS display superior mechanical properties and thermal stability compared to EVM-GMA/silica composites crosslinked by organic peroxide. EVM-GMA composite with 4.5 phr NH2-POSS and 30 phr SiO2 has a tensile strength of 10.7 MPa and an elongation at the break of 240 %. This study introduces a novel and environmentally friendly crosslinking strategy for producing high-performance EVM-GMA composites without additional additives.

Mechanical performance of liquid cold-poured interlayer adhesives in comparison to PVB, EVA, and ionomers

AbstractCurrently, liquid cold-poured adhesives are infrequently used as interlayers of laminated or laminated safety glass in structural glass applications, despite their inherent benefits. The potential advantages of these materials are characterized by easy handling, rapid curing devoid of elevated temperature or pressure requirements, and consequently, a comparatively low energy demand. Despite the prolonged availability of certain products in the market, comprehensive scientific inquiry into their mechanical and thermal material characteristics remains limited. In this paper, two specific liquid cold-poured interlayer adhesives are investigated for their mechanical material properties in an extensive test regime. To be able to classify the characteristic values of the adhesives within a correct framework, the materials currently holding the largest market share, including Polyvinyl Butyral (PVB), Ionomers, and Ethylene Vinyl Acetate (EVA), are also subjected to the experimental program. The temperature dependence of the material behavior is explored through Dynamic Mechanical Thermal Analysis (DMTA) experiments. Furthermore, the time-dependent material behavior at large deformations is scrutinized using various methodologies, such as tensile tests at different strain rates, cyclic tests, creep tests, and relaxation tests, all conducted in uniaxial tension mode. The outcomes of all tests led to promising results for one of the adhesives with advantages over those of PVB and EVA.

Effect of nano-modified EVA on the physical and rheological characteristics of SBR modified asphalt binder

The effects of nanoclay-modified ethylene-vinyl acetate (MEVA) on the physical and rheological properties of styrene–butadiene–rubber (SBR)-modified asphalt binder were investigated. MEVA/SBR composite-modified asphalt binders (MESBR) were prepared with 4 % SBR and varying MEVA content. The effect of MEVA on the properties of SBR-modified asphalt binder (SBRMA) was investigated through penetration, softening point, ductility, viscosity, temperature sweep, and frequency sweep tests. Furthermore, multiple stress creep recovery and bending beam rheometer tests were performed to analyse the deformation resistance and low-temperature performance of MESBR. Additionally, the storage stability of MESBR was evaluated through separation tests and fluorescence microscopy. The results indicated that MEVA addition significantly enhanced the physical and rheological properties of SBRMA both before and after ageing. Compared with SBRMA, MESBR exhibited improved deformation and ageing resistance, making it suitable for use under standard traffic loads at temperatures up to 76℃. However, MEVA exhibited a slightly negative impact on the low-temperature performance and storage stability of MESBR. With the addition of 5 % MEVA, MESBR exhibited favourable comprehensive performance and good storage stability.

Enhancing the effects of solarization-based approaches to suppress Verticillium dahliae inocula affecting tomato in greenhouse

The main concerns regarding the management of soilborne pathogens of vegetable crops through fumigants are due to their detrimental effects on the human health and environment. Due to global restrictions, soil solarization alone or combined with low-impact measures are being re-evaluated as eco-friendly alternatives to replacement of phasing-out or banned fumigants. Three experiments were performed to compare the performance of traditional and innovative films in increasing thermal performance under different partially opened or kept closed greenhouses. The effects of treatment alone or combined with Brassica pellet (Biofence®) incorporation were tested in suppressing microsclerotia of Verticillium dahliae, causing wilt of tomato and vegetable crops. Although inducing different thermal regimes at depths 15 and 30-cm depths, all films were effective in reducing microsclerotia in soil compared to the bare plots under different greenhouse conditions. The performances achieved in closed greenhouse were better than those achieved in greenhouses with the side openings kept open. In these latter conditions, green-colored ethylene-vinyl-acetate (EVA) and uncolored EVA film well performed when combined with Brassica pellet, achieving better results than those obtained in the plots mulched with film or amended alone, respectively. Smoky gray low-density polyethylene (LDPE), followed by uncolored EVA and polyamide virtually impermeable film (PA-VIF) were the most effective in reducing/suppressing V. dahliae microsclerotia within 3-to-8 weeks of treatment in closed greenhouse whereas green EVA showed lesser performance. PA-VIF and EVA green film are attractive since they may be used in combination with biofumigants or left on as mulching for weed control of crops. This paper indicates that sustainable solarization-based approaches with different films alone or integrated with Brassica incorporation can also be successfully pursued against thermo-tolerant pathogens as V. dahliae. Moreover, our findings preliminarily show that the choice of film and treatment duration should be modulated based on the greenhouse operative conditions.

A clean transfer approach to prepare centimetre-scale black phosphorus crystalline multilayers on silicon substrates for field-effect transistors

Recently reported direct growth of highly crystalline centimetre-sized black phosphorus (BP) thin films on mica substrates by pulsed laser deposition (PLD) has attracted considerable research interest. However, an effective and general transfer method to incorporate them into (opto-)electronic devices is still missing. Here, we show a wet transfer method utilizing ethylene-vinyl acetate (EVA) and an ethylene glycol (EG) solution to transfer high-crystalline large-area PLD-BP films onto SiO2/Si substrates. The transferred films were used to fabricate BP-based bottom-gate field-effect transistor (FET) arrays exhibiting good uniformity and continuity, with carrier mobility and current switching ratios comparable to those obtained in as-grown BP films on mica substrates. Our work presents a promising transfer strategy for scalable integration of on-substrate grown 2D BP into devices with more complex structures and further investigation of material properties.

Bonding positional accuracy of attachments and marginal adaptation of in-house aligners - A quality improvement laboratory study.

To evaluate the 3D accuracy of attachment positioning and the adaptation of aligners to attachments using in-house templates made with either polyethylene terephthalate glycol (PETG) or ethylene-vinyl acetate (EVA) and either pressure or vacuum thermoforming machines. Overall, 140 test specimens were resin-printed. Templates for the attachment bonding were made with 1-mm EVA or 0.5-mm PETG laminates. Orthodontic aligners were manufactured with 0.75-mm PETG. The thermoplastification process was carried out using either vacuum or pressure machines. The positional differences between the virtual and bonded attachments were assessed in the X, Y and Z coordinates. The marginal adaptation between the aligners and the attachments was measured. Minor inaccuracies in the positioning of the attachments were observed in all combinations of thermoforming machines and plastic laminates used to fabricate the templates, mainly in the superior-inferior (Z) dimension. PETG performed better than EVA in the anterior region (p < .05). No association was found between thermoplastification machines and the accuracy of the positioning of the attachments (p > .05). While small misadaptations between the aligners and the attachments were observed, the EVA templates performed better than the PETG templates. The inaccuracy of the attachment positioning and the misadaptation of the aligners to the attachments were slight. The vacuum and pressure thermoplastification machines showed no difference in attachment positioning accuracy. The PETG template was better than the EVA template in the anterior region, but the EVA attachments presented a better adaptation to the aligners than the PETG attachments.

Study of dielectric properties of polymer/air plasma treated graphene oxide nanocomposites for electronic applications

In the present study we emphasized on the dielectric properties of Ethylene Vinyl Acetate (EVA) filled with untreated and plasma-treated graphene oxide (GO). The chemical fingerprints of EVA/GO were analysed using FTIR. Decreased ID/IG ratio from 2.99 to 2.75 and 1.60 to 1.16 due to exposed plasma was confirmed by Raman spectroscopy. X-ray diffraction (XRD) disclosed the decreased degree of crystallinity. Electric properties were measured by impedance analyser, dielectric constant was increased upto 11% for untreated GO dispersion and 47% for Air treated Plasma GO dispersed EVA composites. Plasma treatment further improved the exfoliated sites of GO and induced the defects, leading to optimized dielectric properties. Improved dielectric properties of EVA/GO can provide valuable insights into the potential applications in the field of electrical connectors, film capacitors, and pseudo capacitors.

Molecular dynamics simulation of DNAN/DNB cocrystal PBXs.

The DNAN/DNB eutectic is a high-energy explosive eutectic with superior safety and thermal stability compared to traditional melt-cast explosives. However, the addition of polymer binders can effectively enhance its mechanical properties, allowing for continued production demands without the need for changes to existing factory equipment. In this paper, a model of the DNAN/DNB eutectic explosive was established, and five different types of polymers-cis-1,4-polybutadiene (BR), ethylene-vinyl acetate copolymer (EVA), polyethylene glycol (PEG), fluorinated polymer (F2603), and polyvinylidene fluoride (PVDF)-were added to the (1 0 - 1), (1 0 1), and (0 1 1) cleavage planes, respectively, to form polymer-bonded explosives (PBXs). The stability, trigger bond length, mechanical properties, and detonation performance of the various polymer-bound PBXs were predicted retrogressively. Among the five PBX models, the DNAN/DNB/PEG model exhibited the highest binding energy and the shortest trigger bond length, indicating a significant improvement in stability, compatibility, and sensitivity compared to the original eutectic. Additionally, although the detonation performance of DNAN/DNB decreased after the addition of binders, the final results were still satisfactory. Overall, the DNAN/DNB/PEG model demonstrated excellent comprehensive performance, proving that among the many polymer binders, PEG is the optimal choice for DNAN/DNB. Within the Materials Studio software, molecular dynamics (MD) simulations were employed to predict the properties of the DNAN/DNB eutectic PBX. The MD simulation timestep was set to 1fs, with a cumulative simulation duration of 2ns. A 2ns MD simulation was conducted using the isothermal-isobaric ensemble (NPT). The COMPASS force field was applied, and the temperature was fixed at 295K.

Effect of antibacterial masterbatches selection on the crystal structure and properties of nanosilver composite materials

AbstractThe distribution of nanosilver in composite materials with two different matrices is related to the selection of antibacterial masterbatches, which has a profound impact on the antibacterial effectiveness of the composite materials. This study utilized ethylene‐vinyl acetate (EVA) and polypropylene (PP) as base materials to fabricate two types of nanosilver composite materials (C1‐EVA/PP and C2‐EVA/PPP) employing varying methods of antimicrobial masterbatches incorporation. Additionally, EVA‐Ag and PP‐Ag nanosilver composite materials were fabricated via melt blending, along with corresponding neat materials and blends (EVA, PP, and C0‐EVA/PP) for comparison. The study results indicate that the addition of nanosilver did not affect the functional groups of either the neat materials and the EVA/PP blends. SEM analysis revealed that nanosilver was dispersed unevenly in the C1‐EVA/PP substrate, while it was more uniformly distributed in the C2‐EVA/PP substrate. In the antibacterial test, the antibacterial rate of C2‐EVA/PP was higher than that of C1‐EVA/PP (56.0% vs. 40.0%). However, all silver‐containing composite materials did not exhibit antibacterial properties in the agar diffusion test. Additionally, nanosilver exhibited an induced crystallization effect on the PP phase of the C2‐EVA/PP composite material, increasing its Tc2 by 0.8°C. Compared with pure PP, the long period of PP‐Ag increased by 0.7 nm, and its impact resistance improved by 13.8%. By comparison, the long period of EVA‐Ag composite materials increased by only 0.2 nm compared to pure EVA. Both C1‐EVA/PP and C2‐EVA/PP composite materials showed 0.3 nm increase in long period compared to C0‐EVA/PP, with their impact resistance improving by 3.1% and 10.3%, respectively, compared to C0‐EVA/PP. The introduction of nanosilver increased the storage modulus, loss modulus, and apparent viscosity of EVA/PP blends. Optical performance analysis shows that nanosilver increases the internal haze of C1‐EVA/PPP by 60% while reducing the transmittance by 0.3%. The effect of nanosilver on the optical properties of C2‐EVA/PPP composites is relatively small. Therefore, this study provides theoretical guidance for the selection of processing methods for dual‐phase antibacterial materials.Highlights Different antibacterial masterbatch impacts silver distribution in composites. The addition of nanosilver can improve the impact performance of materials. Two process methods were used to prepare low‐silver content composite materials. The antibacterial rate of C2‐EVA/PP is higher than C1‐EVA/PP (56% vs. 40%). This study guides the processing methods for dual‐phase antibacterial materials.

Synergistic effect of TiO2 nanoparticles and poly (ethylene-co-vinyl acetate) on the morphology and crystallization behavior of polylactic acid

The impact of adding ethylene vinyl acetate copolymer (EVA 80) and 1 wt% TiO2 nanoparticles on the morphology and crystallization behavior of poly(lactic acid) blends was investigated using DSC, SEM, and POM. Thermal analysis revealed the enhancement of crystallinity of PLA in the presence of TiO2 and higher EVA 80 content in the blend. The PLA and EVA 80 components showed compatibility, as evidenced by the shift of the glass transition temperatures of the PLA phase in the blend to lower values compared to neat PLA. The lower temperature shift of the cold crystallization of the PLA and the formation of the small spherulites of the PLA in the blends indicated that the EVA 80 and TiO2 act as a nucleating agent for crystallization. The non-isothermal crystallization parameters of the composites were evaluated using Avrami's modified model, the MO approach, and Friedman’s isoconversional method. The Avrami’s modified rate constant (K) and the effective activation energy values significantly increased with the incorporation of EVA 80 and TiO2 nanoparticles. Furthermore, the thermogravimetric analysis (TGA) showed improved thermal stability of PLA by adding EVA 80 and TiO2.

COMPARISON OF TRIETHANOLAMINE (TEA) AND ETHYL VINYL ACETATE (EVA) AS FLOW IMPROVERS OF CRUDE OIL.

This research presents a study on the comparative analysis of the efficiencies of triethanolamine (TEA) and ethylvinylacetate (EVA) as flow improvers for crude oil transport. Varied concentrations (by volume percentage) of 0%, 0.025%, 0.05%, 0.1%, 0.2%, 0.4% and 1% of triethanolamine were introduced into separate but same quantities of crude oil and stirred. The viscosity and pour points were monitored at varied temperatures (30oC, 40oC, 50oC, 60oC, 70oC) to ascertain optimum concentration and temperature of best flow improvement with that of zero concentration serving as control. Similar thing was done with EVA at same conditions. TEA and EVA both drastically dropped viscosity of the crude close to what temperature alone could offer but rose immediately after the minimum concentration of 0.025% with EVA and TEA on further diluent addition. TEA viscosity rose steeply and later tended towards a constant viscosity. This was also the trend with EVA, but it rose gently unlike TEA at increased concentration of the additive. Using room temperature (30oC) for the two additives (TEA and EVA) as reference point at 0.025% concentration of each to the same volume of crude oil, TEA gave a minimum viscosity of 0.1124centistokes and EVA gave 0.1184centistokes. Similar trend was also observed at the apex temperature (70oC) at 0.025% concentration (TEA viscosity = 0.0997centistokes and EVA = 0.1015centistokes). In the end, TEA was observed to be better than EVA although EVA has its own relative advantage especially at higher temperatures and concentrations. Higher temperature from 40oC and above degraded TEA but not EVA, as a result was inhibitory to the reverse rise in viscosity in TEA. Hence, having established TEA and EVA as good drag reducing agents, the additives if used in the proper calculated quantities will act optimally in improving crude oil transport. Outcome of this research will find application in our oil and gas industry where challenges in crude oil transport has been overwhelming as a result of wax formations in the pipelines.

The seasonal variation and ecological risk of microplastics in the Lower Ganges River, Bangladesh.

Microplastic (MP) pollution has gained considerable attention in various ecosystems; however, it has received relatively less attention in freshwater-riverine environments than in other ecosystems. The Ganges River Delta, one of the world's most densely populated areas, is a potential source of MP pollution in the freshwater ecosystem. MPs were identified throughout the year in the lower Ganges River water. Seasonally, the highest abundance was observed during the monsoon (14.66 ± 2.06 MPs/L), followed by the pre-monsoon (13.46 ± 1.75 MPs/L) and post-monsoon (11.50 ± 0.40 MPs/L). Throughout the year, MP discharge was estimated at 4.12 × 1012 to 2.17 × 1013 MPs/year. Fourier transformed infrared spectroscopy identified plastic polymers in the water, like ethylene vinyl acetate, polystyrene, polypropylene, polyethylene, and nylon. Moderate contamination by MPs was assessed throughout the year. Significant correlations between MP abundance and both rainfall and discharge were observed. It is essential to implement preventative measures in the Ganges River Basin to mitigate MP pollution before the situation worsens. PRACTITIONER POINTS: Throughout the year, MP concentration ranged from 10.67 to 20.33 MPs/L The highest MP occurrence was observed in the monsoon season (14.66 ± 2.06 MPs/L) The lowest abundance was detected in the post-monsoon period (11.50 ± 0.40 MPs/L) There was a moderate level of MP contamination in the lower Ganges River water It was shown that discharge and rainfall were correlated with MP abundance.

EVA implants for controlled drug delivery to the inner ear

This study evaluated the potential of poly(ethylene vinyl acetate) (EVA) copolymers as matrix formers in miniaturised implants, allowing to achieve controlled drug delivery into the inner ear. Due to the blood-cochlea barrier, it is impossible to reliably deliver a drug to this tiny and highly sensitive organ in clinical practice. To overcome this bottleneck, different EVA implants were prepared by hot melt extrusion, altering the vinyl acetate content and implant diameter. Dexamethasone was incorporated as a drug with anti-inflammatory and anti-fibrotic activity. Its release was measured into artificial perilymph, and the systems were thoroughly characterised before and after exposure to the medium by optical and scanning electron microscopy, SEM-EDX analysis, DSC, X-ray powder diffraction, X-ray microtomography and texture analysis. Notably, the resulting drug release rates were much higher than from silicone-based implants of similar size. Furthermore, varying the vinyl acetate content allowed for adjusting the desired release patterns effectively: With decreasing vinyl acetate content, the crystallinity of the copolymer increased, and the release rate decreased. Interestingly, the drug was homogeneously distributed as tiny crystals throughout the polymeric matrices. Upon contact with aqueous fluids, water penetrates the implants and dissolves the drug, which subsequently diffuses out of the device. Importantly, no noteworthy system swelling or shrinking was observed for up to 10 months upon exposure to the release medium, irrespective of the EVA grade. Also, the mechanical properties of the implants can be expected to allow for administration into the inner ear of a patient, being neither too flexible nor too rigid.

Ultra-fast light repair, ultrasensitive, large strain detection range PDA@RGO/EVA composites fiber flexible strain sensor

The sensor fabricated from high-molecular polymer is soft, lightweight, and biocompatible; however, traditional high-molecular polymers suffer from viscoelasticity and poor cycle stability. To address these issues, it is essential to develop flexible matrix materials that can overcome viscoelasticity, ensuring high sensitivity and long-term use under large strains for next-generation wearable intelligent devices. In this study, ethylene-vinyl acetate (EVA) with a shape memory effect was utilized as the substrate for a flexible sensor，the shape memory effect of EVA can eliminate the residual strain generated by each long time of use to improve its service life. A polydopamine@reduced graphene oxide (PDA@RGO)/EVA fiber flexible strain sensor was fabricated through melt extrusion, swelling ultrasound, and in-situ polymerization techniques. The resulting sensor exhibits high sensitivity (gauge factor=1801.21), a wide strain detection range (strain = 193 %), and excellent stability and durability (2000 cycles). Notably, the PDA@RGO/EVA fiber flexible strain sensor demonstrates exceptional dual thermal and light repair functions, with light repair achieving a repair speed of 5 seconds, 100 % electrical performance repair efficiency, and perfect consistency in relative resistance response before and after repair. Furthermore, the PDA@RGO/EVA strain sensor can monitor finger and wrist movements in real-time with high accuracy, highlighting its significant potential application in the wearable technology field.

Analysis of the self-healing mechanism of TB compound-modified asphalt based on molecular dynamics

To investigate the intrinsic self-healing behavior of terminal blend (TB)-modified asphalt (TBMA), this study establishes four models of matrix asphalt, TBMA, TBMA containing styrene-butadiene-styrene (TB_SBS), and TBMA containing ethylene vinyl acetate (TB_EVA) based on molecular dynamics, and the self-healing ability of the four types of asphalt was evaluated by means of the diffusion coefficient, diffusion activation energy, and pre-exponential factor. Finally, the study analyzes and validates the self-healing performance of the asphalt through fatigue shear-healing tests. The results showed that the self-healing potentials of the four types of asphalt, as determined by the diffusion coefficient, diffusion activation energy, and pre-exponential factor, were (in descending order) TB_SBS, TBMA, TB_EVA, and matrix asphalt. In addition, the diffusion coefficient of the TBMA was increased relative to the matrix asphalt, SBS polymer further increased the diffusion coefficient, and EVA modifier had an inhibitory effect, which was related to the viscoelasticity and mechanical performance of the material. Besides, the diffusion coefficient enhancement effect of the SBS modifier on the TBMA was greater than the inhibition effect, which mainly derived from the enhancement of the diffusion coefficient of lightweight components in significantly enhancing the self-healing ability the TBMA. From microscopic and macroscopic scales, the shear-fatigue healing tests showed excellent correlation with the simulation results, demonstrating that molecular dynamics can be used to model the self-healing process of asphalt.

Thermal, rheological, and aging characterization of ethylene vinyl acetate polymer modified asphalt binder

Thermal, rheological, and aging characterization of ethylene vinyl acetate polymer modified asphalt binder

Hernia 3D training model: a new inguinal hernia 3D-printed simulator.

Barros et al. demonstrated a 3D printed model that exhibits anatomical representativeness, low cost, and scalability. The model was created based on subtraction data obtained from computed tomography scans. Images were modeled and reconstructed in 3D to display the male inguinal region, typically viewed using a laparoscopic approach. To evaluate the functionality and quality of the anatomical representation of the hernia 3D training model. A model was created based on subtraction data derived from computed tomography scans of the pelvic bones and lumbar spine using the Blender 3.2.2 software program. Images were modeled and reconstructed in 3D to display the male inguinal region, typically viewed using a laparoscopic approach. Polylactic acid plastic was used to print the model. Some structures were made using ethylene vinyl acetate to enable possible material replacement and model reutilization. Thirty surgeons with various training levels were invited to use the model. Transabdominal inguinal hernioplasty was performed by simulating the same steps as those of a laparoscopic surgery, and the surgeons answered a questionnaire regarding the simulation. Twenty-eight surgeons responded, seven of whom were experts in the treatment of abdominal wall hernias. The model was deemed easy to use, realistic, and anatomically precise, establishing it as a valuable supplement to minimally invasive surgery training. The evaluation of this 3D model was favorable, as it accurately depicted the inguinal region anatomically, while also proving to be cost-effective for training purposes. The model could be a good option, particularly beneficial for training surgeons at the beginning of their careers.

Influence of Some Factors on Propolis Dilution by Honey Bees

Propolis is a sticky resinous substance collected from buds, leaves, stems of wild plants and processed by bees. Currently, bee behaviour during the collection of propolis, its botanical origin and sources of production have been studied. The process of propolis accumulation in bee nests and the factors influencing the intensity and productivity of bee colonies need to be further studied, which will allow to control the propolis productivity of bees in the future. To better understand the behavior of bees when liquefying propolis with enzymes from the mandibular glands, we conducted studies using specially designed collectors. Three different types of mesh were used in the collectors: ethylene vinyl acetate (EVA), polyethylene, and nylon. All three types of meshes had different hole diameters. As a result of the study, we determined the diameter of propolis droplets formed in all collectors, deviations from roundness, and the distance at which the droplets fly away from the edge of the glass substrates. We conclude that the type of mesh materials does not influence the behavior of bees in liquefying propolis. The size of the mesh holes affects the distance from the edge of the glass substrate to the centre of the propolis drops.

Comparative Study of the Foaming Behavior of Ethylene-Vinyl Acetate Copolymer Foams Fabricated Using Chemical and Physical Foaming Processes.

Ethylene-vinyl acetate copolymer (EVA), a crucial elastomeric resin, finds extensive application in the footwear industry. Conventional chemical foaming agents, including azodicarbonamide and 4,4'-oxybis(benzenesulfonyl hydrazide), have been identified as environmentally problematic. Hence, this study explores the potential of physical foaming of EVA using supercritical nitrogen as a sustainable alternative, garnering considerable interest in both academia and industry. The EVA formulations and processing parameters were optimized and EVA foams with densities between 0.15 and 0.25 g/cm3 were produced. Key findings demonstrate that physical foaming not only reduces environmental impact but also enhances product quality by a uniform cell structure with small cell size (50-100 μm), a wide foaming temperature window (120-180 °C), and lower energy consumption. The research further elucidates the mechanisms of cell nucleation and growth within the crosslinked EVA network, highlighting the critical role of blowing agent dispersion and localized crosslinking around nucleated cells in defining the foam's cellular morphology. These findings offer valuable insights for producing EVA foams with a more controllable cellular structure, utilizing physical foaming techniques.

Integrating machine learning and the finite element method for assessing stiffness degradation in photovoltaic modules

This study introduces a novel machine learning (ML) method utilizing a stacked auto-encoder network to predict stiffness degradation in photovoltaic (PV) modules with pre-existing cracks. The input data for the training process was derived from numerical simulations, ensuring a comprehensive representation of module behavior under various conditions. The findings highlight the robust predictive capability of the model, as evidenced by its impressive R2 value of 0.961 and notably low root mean square error (RMSE) of 4.02%. These metrics significantly outperform those of other conventional methods, including the artificial neural network with R2 of 0.905 and RMSE of 9.43%, the space vector machine with R2 of 0.827 and RMSE of 17.93%, and the random forest (RF) with R2 of 0.899 and RMSE of 11.02%. Moreover, the findings suggest that the predictive dynamics of degradation are affected by the varying weight functions of different input parameters, such as climate temperature (CT), grain size (GS), material effort, and pre-crack size, as the degradation level changes. Furthermore, a geometric analysis reveals model deficiencies where significant overestimations correlate with thicker glass components, while pronounced underestimations are predominantly associated with thinner layers of polycrystalline silicon wafer and Ethylene Vinyl Acetate in the module. As a case study, it demonstrated that to maintain a constant degradation level between 1.30 and 1.32 in a PV module with components featuring consistent geometric attributes, the input parameters must be kept within specific ranges: CT ranging from 33 °C to 57 °C, GS ranging from 36 to 81 μm, material effort ranging from 0.74 to 0.81, and pre-crack size ranging from 24 to 32 μm. Therefore, this underscores that the ML model not only predicts degradation but also delineates the parameter space required to achieve a consistent output value.