Ethylene Vinyl Acetate Copolymer Research Articles

In situ growth of Ag nanoparticles on the surface of MXene by γ-ray irradiation to fabricate EVA composite: the improvement of flame retardancy, smoke suppression, and mechanical properties

A large amount of toxic smoke and heat generated by the combustion of ethylene vinyl acetate copolymer (EVA) poses a significant threat to human fire escape evacuation. This work aims to use γ-ray to prepare e-MXene@Ag hybrid flame-retardant materials by the method of in-situ reduction, and EVA composites are prepared by melt blending to reduce the smoke and toxic gases produced during combustion significantly. Compared with pure EVA, the total heat release, total smoke release, and the production rate of CO and CO2 produced by the combustion of EVA composite with 1 wt% e-MXene@Ag1.0 decreased by 30.3%, 33.3%, 18.2%, and 20.1% respectively. The fire hazard reduction of EVA composite materials was due to the physical barrier, catalytic carbonization and adsorption of the e-MXene@Ag1.0 hybrid. In addition, e-MXene@Ag1.0 can also further increase the mechanical properties of EVA composites due to its own ‘multi-contact point limit structure’.

Smart reconfigurable electromagnetic metamaterials based on thermadapt shape memory Poly(ethylene–vinyl acetate)

Smart reconfigurable metamaterials can better adapt to changing electromagnetic environments and broaden the range of applications. However, constructing electromagnetic reconfigurable metamaterials, especially those with large areas or applied to complex surfaces via a universal approach, is still a challenge. Here, we introduce a smart reconfigurable metamaterial consisting of a thermadapt shape memory polymer ethylene vinyl acetate copolymer (EVA) matrix and a flowable liquid–metal resonant unit. Based on the excellent self-healing properties of EVA, large-area metamaterials can be constructed by thermal assembly of metamaterial units. In addition, the original shape of the metamaterial can be reprogrammed to apply to complex three-dimensional surfaces with the reprocessing properties of EVA. Moreover, by utilizing the shape memory performance of the EVA, the temporary resonant frequency of the metamaterial can be set by programming and the resonant frequency tuning of the metamaterial can be controlled under external temperature stimulation, achieving noncontact tuning. In the future, this concept can be broadly applied in fields such as complex structure stealth layers and multifunction filters.

Synthesis of stable fluorescent ethylene-vinyl acetate copolymers based on in-situ grafted rare-earth organic complexes and antioxidants through transesterification

Synthesis of stable fluorescent ethylene-vinyl acetate copolymers based on in-situ grafted rare-earth organic complexes and antioxidants through transesterification

Molecular dynamics simulation of the interaction between aggregates and calcium silicate hydrate and influence of ethylene vinyl acetate copolymer modifier

ABSTRACT It is known that the bonding strength of the aggregate/cement interface affects the overall durability of concrete. However, whether the modification of ethylene vinyl acetate (EVA) copolymer affects the interface interaction between aggregates and cementitious materials is unclear. This study analyzed the interface's static structure, dynamic characteristics, and binding energy. The interaction mechanisms between acid and alkali aggregates and hydrated calcium silicate and the modification effect of EVA were compared. The calculation results of relative density distribution and radial distribution function verified the difference in the structure of EVA-modified acidic or alkaline interfaces. EVA polymer chains significantly blocked the flow of Ca atoms in CaO at the CaO/C-S-H interface and weakened the van der Waals effect at the interface. The mean square displacement and time correlation function analysis indicate that all unmodified interfaces have stable interface structures. After EVA modification, the stability of CaCa-HW decreased significantly, hindered the generation of hydration products, and verified the weak Ca atom transport at the CaO/C-S-H interface. In addition, the adhesion energy of SiO2/C-S-H and CaO/C-S-H after EVA modification decreased by 6% and 14.8%, respectively, quantifying the modification effect of EVA.

Achieving heat storage coatings from ethylene vinyl acetate copolymers and phase change nano-capsules with excellent flame-retardant and thermal comfort performances

The heat-storage coatings from ethylene vinyl acetate (EVA) copolymers were developed by incorporating in-situ synthesized phase change nano-capsules (NEPCMs). The coatings were applied to the interior walls of the building, aimed at enhancing thermal storage and flame-retardant performances. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) are utilized to evaluate the chemical composition of the NEPCMs. At the same time, the thermal properties and microstructure of NEPCMs and the coatings are analyzed using differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The enthalpy of NEPCMs is 158.14 J/g, while that of heat-storage coatings is 56.45 J/g. NEPCMs and heat-storage coatings exhibit excellent thermal storage performance even after 200 heating-cooling cycles, demonstrating the excellent thermal stability of NEPCMs and heat-storage coatings. Furthermore, excellent flame-retardant properties are also provided by the heat-storage coating. In dynamic heat transfer experiments, under the same conditions, the heat-storage coatings were capable of maintaining the chamber in the thermal comfort zone (24–28 °C) for 141 min, while the conventional coatings lasted only 34 min. The results show that incorporating heat-storage coatings can effectively enhance the thermal regulation performance of interior walls and improve the thermal comfort of indoor environments. Therefore, heat-storage coatings hold a high potential for application in energy-saving buildings.

Combining Siloxane-Based polybenzoxazine with Poly(ethylene-co-vinyl acetate/hydroxyl) for tougher, more Stable, and Self-Healable materials

Cross-linked EVOH containing dynamic silyl ether bonds with improved toughness and processability have been prepared by taking advantage of both ethylene vinyl alcohol (EVOH) and benzoxazine chemistry. For that, the cross-linked EVOH was synthesized through a trans etherification reaction between siloxane mono-functional benzoxazine and pendant hydroxyl groups on ethylene vinyl alcohol (EVOH) copolymer. The precursor EVOH copolymer was obtained by hydrolysis of the commercially available and inexpensive ethylene–vinyl acetate copolymer (EVA). The chemical structures of polymers were analyzed by proton nuclear magnetic resonance (1H NMR) spectra and Fourier transform infrared (FTIR) spectroscopy. The curing and thermal stability were researched by using differential scanning calorimetry (DSC) and a thermogravimetric analyzer (TGA), respectively. The mechanical properties via the stress–strain analysis were examined to identify the effect of the benzoxazines with the silyl ether group on the toughness and self-healing ability of the modified EVOH.

4D Printing of novel poly(ethylene-vinyl acetate) / poly(butyl methacrylate-co-isobutyl methacrylate) shape memory polymer blends

4D printing is a technology that combines additive manufacturing with shape memory polymers, aiming to enhance the functionality of 3D printed structures. Filaments made from thermoplastic polymers are commonly used in Fused Deposition Modeling (FDM), which is one of the most prevalent types of 3D printing. Here, novel heat-responsive shape memory polymer blends were produced from ethylene-vinyl acetate copolymer (EVA) and poly(butyl methacrylate-co-isobutyl metacrylate) polymers. The effect of blend composition on the morphological, thermal, mechanical, and shape memory properties was investigated. The blend (60E-40B) containing 60 % by weight EVA and 40 % by weight BMA-co-iBMA exhibited optimum shape memory performance with a shape fixing (Rf) of 94.1 % and a shape recovery (Rr) of 94.5 % at a shape transition temperature (Ttrans) of 55 °C. Filament for the 60E-40B blend was produced for FDM type 3D printers, and 4D parts for various applications were printed using this filament. These 4D printed parts, designed for robotic grippers, self-assemble rivets, movable cog-wheel teeth, surface traps, and finger splints, displayed shape recovery characteristics in both hot oven and hot water environments.

Improved processability for ultra‐high molecular weight polyethylene/polyolefin elastomer composites: Effect of ethylenevinyl acetate copolymer

Improved processability for ultra‐high molecular weight polyethylene/polyolefin elastomer composites: Effect of ethylenevinyl acetate copolymer

Gamma radiation-induced grafting of poly(butyl acrylate) onto ethylene vinyl acetate copolymer for improved crude oil flowability

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.

Environmental fatigue crack growth of PV glass/EVA laminates in the melting range

AbstractThe delamination of encapsulants in photovoltaic (PV) modules is a common issue that leads to power loss due to optical losses. Encapsulant debonding is usually examined under monotonic loading conditions subsequent to environmental exposure such as damp heat. Service‐relevant, superimposed environmental‐mechanical fatigue loads are not considered adequately. Hence, the environmental fatigue delamination resistance of thermally toughened double glass laminates with an ethylene vinyl acetate copolymer (EVA) adhesive layer was investigated in this study. Focus was given to the melting range of EVA, in which the non‐crosslinked crystalline phase fraction is already in the partly molten state. Double cantilever beam specimens were tested on an electrodynamic test machine at temperatures of 60, 70, 80, and 90°C and relative humidity (rh) levels of 2%, 30%, 50%, and 80%. The fractured surfaces were characterized by digital microscopy, Fourier transform infrared spectroscopy (FTIR), X‐ray photoelectron spectroscopy (XPS), and differential scanning calorimetry (DSC). The cyclic fatigue tests revealed a decay in delamination resistance at elevated temperature and humidity levels. At 70°C, the delamination resistance was low, regardless of the relative humidity. Most of the laminates failed by debonding. XPS analysis showed a reduction of the C=O and C–O content, along with an increase in Si–O content with increasing relative humidity. For laminates tested at 60 and 70°C, an EVA recrystallization peak was observed in DSC experiments. This peak was shifted to significantly higher temperatures at 80% rh. XPS and DSC indicated local hydrolysis within the porous fracture process zone ahead of the crack tip. Consequently, acetic acid formation led to a decrease in delamination resistance, resulting in lower fatigue threshold values. The investigations confirmed the significant impact of environmental conditions on the fatigue delamination resistance within glass/encapsulant laminates. Notably, acetic acid formation and a significant reduction in delamination properties were observed after around 100 h of environmental fatigue exposure.

Modelling the non-isothermal curing kinetics of peroxide crosslinking polyolefin copolymers for photovoltaic module lamination

This study presents a model for determining the non-isothermal curing kinetics of peroxide crosslinking polyolefin copolymers used for encapsulation of silicon solar cells in photovoltaic modules. Therefore, rheological data of ethylene vinyl acetate copolymer (EVA) and polyolefin elastomer (POE) were analyzed. The curing kinetics were described assuming a temperature dependent Arrhenius rate coefficient and implementing a reaction rate model. Validation was performed under isothermal and non-isothermal conditions. An excellent agreement of experimental and model data was ascertained. The model was used to determine the non-isothermal crosslinking conversion during lamination of EVA or POE based photovoltaic mini-modules. Temperatures were tracked by positioning seven sensors within the mini-modules. Moreover, a thermal simulation model was implemented. Also on module level, the experimental results corroborated the simulated data. A lamination temperature of 150 °C led to insufficient curing of POE based modules. Similar conversion rates were achieved for EVA and POE encapsulants at 150 and 160 °C, respectively.

Recycled rubber wastes-based polymer composites with flame retardancy and electrical conductivity: Rational design, modeling and optimization

Polymer recycling techniques experience a maturity period of design and application. Rubbers comprise a high proportion of polymer wastes, highly flammable and impossible to re-melt. Polymer composites based on ground tire rubber (GTR) and ethylene-vinyl acetate copolymer (EVA) containing carbon black (CB) (1–50 phr), with variable EVA/GTR weight composition (10/90, 25/75, 50/50, 75/25 and 90/10), and processing temperature (Low: 100 °C and High: 200 °C) were designed applying Design of Experiments (DOE) approach of Optimal Design. The properties and performance features were experimentally evaluated. The tensile strength (TS) and elongation at break (EB) were optimized using Desirability Function (DF) approach. A wide fluidity window (Labeled POOR, GOOD, and EXCELLENT) and mechanical properties were observed. Overall, higher values of EB were assigned to samples processed at 200 °C. Cubic regression modeling and DF optimization of TS and EB indicated unlikely that one expect a TS ≥ 3 MPa, while EB values more than 500% were likely regardless of CB content for EVA-rich composites. The electrical properties of CB/EVA/GTR samples were examined by impedance spectroscopy technique. An interesting relationship was observed between the DC conductivity and the EVA/GTR ratio and processing temperature. GTR-rich samples showed much higher conductivity than EVA-dominated samples, attributed to the presence of CB in the rubber waste, which, together with the added CB, was able to create conduction paths for the transported electrons. Higher processing temperature of 200 °C improved dispersion of the added CB, i.e. a more even distribution of the conductive phase in the matrix. The uniform and evenly dispersed domains of particles were detected by SEM images for highly CB loaded composites. Surprisingly, 50/50 EVA/GTR composites were resilient against flame, while thermally stable ones in TGA measurements were highly CB loaded ones.

Effective decapsulation method for photovoltaic modules: Limonene-induced EVA controlled swelling under sonication and debonding mechanism analysis

Waste crystalline silicon (c-Si) solar cells are rich in metal resources. The detachment of ethylene-vinyl acetate (EVA) copolymer is a critical step in the recycling of end-of-life (EoL) c-Si photovoltaic (PV) modules, but a clean and high-efficiency adhesive removal method is absent. In this study, we presented a green solvent-based approach using limonene with ultrasound assistance for the efficient delamination of EVA from c-Si PV modules. By adjusting the concentration of limonene solution, the degree of swelling of EVA was effectively controlled, reducing the risk of battery damage caused by uneven swelling. The application of an ultrasonic physical field to the swelling system expedited the diffusion and penetration of the swelling agent between the EVA layers, while simultaneously supplying energy for the fracture of cross-linking bonds. Under the optimized laboratory-scale condition (70 °C, 0.5 h and 0.1 M limonene), complete separation of the glass and backsheet from the EVA bonding layer was achieved. The intact c-Si solar cells thus have the potential to be fully recovered in subsequent processes. FT-IR tests and density functional theory (DFT) simulations confirmed that under ultrasound conditions, limonene molecules selectively attacked crosslinking bridges and side chains of ethyl vinyl acetate in the EVA molecular chain. This induced the breakdown of the EVA crosslinked network structure, resulting in a reduction in adhesive strength and ultimately achieving interlayer separation in 20min. The findings of this study provide theoretical support and technical insights for the clean and efficient recycling of PV modules.

Insights into Factors Affecting Ethylene-Vinyl Acetate Copolymer Crystallinity in Islatravir Implant.

Islatravir, a highly potent nucleoside reverse transcriptase translocation inhibitor (NRTTI) for the treatment of HIV, has great potential to be formulated as ethylene-vinyl acetate (EVA) copolymer-based implants via hot melt extrusion. The crystallinity of EVA determines its physical and rheological properties and may impact the drug-eluting implant performance. Herein, we describe the systematic analysis of factors affecting the EVA crystallinity in islatravir implants. Differential scanning calorimetry (DSC) on EVA and solid-state NMR revealed drug loading promoted EVA crystallization, whereas BaSO4 loading had negligible impact on EVA crystallinity. The sterilization through γ-irradiation appeared to significantly impact the EVA crystallinity and surface characteristics of the implants. Furthermore, DSC analysis of thin implant slices prepared with an ultramicrotome indicated that the surface layer of the implant was more crystalline than the core. These findings provide critical insights into factors affecting the crystallinity, mechanical properties, and physicochemical properties of the EVA polymer matrix of extruded islatravir implants.

Tribological performance of ficus carica oil modified with ethylene vinyl acetate and sodium dodecyl benzenesulfonate

Purpose Due to the environmental issues caused by petroleum lubricants used in lubrication, the concept of creating various bio-lubricants requires research globally. Thus, this study aims to develop, characterize and test the base ficus carica oil (fig oil) for its ethylene vinyl acetate copolymer (EVA) and sodium dodecylbenzene sulfonate (SDBS) content. Design/methodology/approach The sample characterization was done using the Fourier transmission infrared spectrum, whereas the morphologies of the EVA, SDBS particles and lubricated surfaces were carried out under scanning electron microscope equipment. To ensure the homogeneity of the solution (base oil and additives), the formulations were subjected to the sonication process. The anti-friction and anti-wear properties of EVA and SDBS particles as lubricant additives were investigated using a ball on a flat high-frequency reciprocating rig tribo-tester. Findings According to the findings, the base oil’s anti-friction and anti-wear capabilities can be greatly enhanced by the additions. revealed that the best results were obtained when 1.2% EVA + 2% SDBS was applied for the examination of wear (597.8 µm) and friction coefficient (0.106). Commercial references were used, nevertheless, and the results were excellent. This is because the particles in the contact area during lubrication have strong solubility and quickly penetrate the contact zone. The lubricating mechanisms were explained by a tribological model of the EVA + SDBS and SDBS particles. Research limitations/implications The coefficient of friction and wear reduction caused by the use of the additives will certainly enhance system performance and protect the machine components from excessive wear that could cause damage or failure. Originality/value The originality and uniqueness of this work are officially affirmed by the authors. The authors’ autonomous and original contribution to the development of sustainable lubrication is represented in this work. To the best of the authors’ knowledge, no other study has been published or made publicly available that duplicates the precise scope and goals of our research, and this conclusion is based on a thorough literature assessment.

Generalized nomogram for determining the type of structure and composition of fire-resistant polymer composite materials with fire-retardant fillers

A generalized nomogram for designing the type of structure and compositions of dispersion-filled polymer composite materials (DFPCM) with flame retardant fillers having high combustion resistance and a high oxygen index (OI) is proposed on the example of polymer composite based on ethylene-vinyl acetate copolymer (EVA) and magnesium hydroxide of EcoPyrene brand. The nomogram combines into a single whole the previously obtained dependencies for the calculation and organization of different types of structure of DFPCM and data on combustion resistance and OI values.

Development and characterization of 3D printed ethylene vinyl acetate (EVA) as drug delivery device for the treatment of overactive bladder

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.

Assessing Field Degradation of Photovoltaic Modules by Near‐Infrared Absorption Spectroscopy of Ethylene Vinyl Acetate Encapsulant

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.

Preparation and performance analysis of polyamide-based rapid repair material for asphalt pavement shallow groove

In order to effectively remedy shallow grooves on asphalt pavements, this study presents an innovative solution, termed Polyamide-based Asphalt Pavement Shallow Groove Rapid Repair Material (PA-SGRRM). This material employs polyamide 6 (PA6) as the matrix resin, in conjunction with polypropylene (PP), ethylene-vinyl acetate copolymer (EVA), and maleic anhydride-grafted polyethylene-octene copolymer (POE-g-MAH). It is manufactured through an extrusion granulation process. At the outset, a molecular dynamics approach was employed to assess the compatibility of the primary constituents and the adhesion between the matrix resin and asphalt, confirming the rationale behind the material selection. Subsequently, the orthogonal experimental design method was utilized to investigate the influence of design parameters (POE-g-MAH content, PP content, and EVA content) on the flexural strength, tensile strength, low-temperature toughness, and melt flow rate of PA-SGRRM. Following this, we prepared samples with the optimal proportions of EVA and POE-g-MAH and conducted a separate analysis to evaluate the impact of PP on the saturated moisture content of PA-SGRRM. Finally, we employed Scanning electron microscopy (SEM) to observe the microstructures of the low-temperature fracture surface and ambient temperature tensile fracture surface of the PA-SGRRM and employed Fourier transform infrared spectroscopy (FTIR) to deduce the primary chemical reactions occurring within the PA-SGRRM. The results demonstrated that POE-g-MAH played a crucial role in enhancing the compatibility of the simulated hybrid system consisting of PP and PA6. Additionally, it was observed that adhesion between PA6 and asphalt existed, with a gradual decrease as temperature rose. The content of POE-g-MAH and PP were the two primary parameters influencing the performance of PA-SGRRM. POE-g-MAH exerted a significant adverse impact on the flexural strength, tensile strength, and melt flow rate of PA-SGRRM, while substantially improving its low-temperature toughness. The PP positively reduced the water absorption characteristics of PA-SGRRM. Based on the experimental results, the optimal combination of design parameters for PA-SGRRM is recommended.

Repairing Performance of Polymer-Modified Cement-Based Thin Spray-On Liners on Pre-Cracked Rock-like Specimens

With the development of coal mining and the increase in excavation depth, the stress on roadway surrounding rock is also increasing. This creates conditions for crack development in the roadway, so it is urgent to develop rock repair materials with excellent performance. The ability of thin spray-on liner (TSL) to repair rock and concrete opens up the possibility of reusing abandoned roadways. The ability of TSL to support the surrounding rock is also important in preventing the generation of roadway waste. In this paper, styrene–acrylic emulsion (SAE), vinyl acetate–ethylene copolymer emulsion (VAE), and polyvinyl alcohol powder (PVA) were used to prepare three TSLs. Rock-like materials were configured using cement mortar according to similar principles. Three types of TSLs were tested for basic properties such as viscosity and mechanical strength, which provided data to support the explanation of the repair performance of TSLs. Three TSLs were used to repair pre-cracked rock-like specimens (PR). The number of brushing times and the angle of PR’s cracks were regarded as test variables. Changes in the mechanical strength of repaired PRs were tested by compressive and flexural tests. TSL repair performance was evaluated with the help of mechanical strength changes. Results show that polyvinyl alcohol powder modified cement-based thin spray-on liner is most suitable for repairing rock cracks; as the thickness of the brush slurry increases, its repair performance continues to improve. This paper can provide experience and a theoretical basis for the research of other rock repair materials, and it is also instructive for repairing shotcrete in the roadway.