Ethylene Vinyl Acetate Research Articles

Processing plastic waste via pyrolysis-thermolysis into hydrogen and solid carbon additive to ethylene-vinyl acetate foam for cushioning applications

A strategy for enhancing value creation from pyrolysis gas and oil, derived from plastic waste, through the generation of two additional outputs of solid carbon and hydrogen was investigated. Three types of hard-to-recycle plastic waste (marine plastic litter, household mixed plastics and cosmetic products packaging) were thermally treated in two stages: (i) decomposition of feedstock into gas and oil via pyrolysis at 600 °C; and (ii) thermolytic conversion of the pyrolysis gas and a fraction of oil into hydrogen and solid carbon at 1300 °C separately. The thermolysis of both pyrolysis gas and oil fractions predominantly resulted in the production of solid carbon (39–70 wt% per plastic feedstock and carbon content of 91.3–98.6 wt%) and H2-rich gas (H2 yield of 5.9–10.8 wt% per plastic waste feedstock and H2 content of 71.4–97.2 vol% per gas volume). The incorporation of pyrolysis oil into the thermolysis process could enhance the outputs of solid carbon and hydrogen. Characterizations of solid carbon and hydrogen obtained from pyrolysis gas and oil fractions were further conducted. The observed similar properties of H2 and solid carbon from pyrolysis gas and oil supported the feasibility of introducing all the pyrolytic products together into the thermolysis process without condensation of oil. To enhance the value of these solid carbon derived from plastics for practical usage, we utilized the obtained solid carbon as a reinforcing agent for polymer composite foam development. The solid carbon reinforced composite foam displayed great abrasion resistance (wear loss: 240 mg), compression strength (0.347 MPa), and dynamic impact properties (energy returned: 124 J/m and energy absorbed: 57.3 J/m), emphasizing the viability of solid carbon as a nucleating agent and reinforcing filler in polymer foam for cushioning applications. Overall, the strategy of pyrolysis-thermolysis, which harnesses both pyrolysis gas and oil, unlocks additional value creation by producing two new outputs from plastic waste. Depending on the market prices for solid carbon and hydrogen, this can substantially change the economics of plastic waste management and create new revenue streams, incentivizing plastic waste collection and processing.

Effects of zeolite loaded with silver, copper, or zinc ions on antimicrobial properties of the ethylene‐vinyl acetate copolymer

AbstractThe improvement of antimicrobial activity of ethylene‐vinyl acetate (EVA) resin is of significant importance from the hygienic point of view. Hence, the present work aimed to improve antimicrobial performance of the polymer with the aid of a novel, effective and low‐cost additive. Accordingly, the effects of incorporating Mobil‐twenty‐two zeolite loaded with silver, copper and zinc salts to EVA on antimicrobial activity of the polymer was investigated in this study. The used zeolite was hydrothermally synthesized and doped with silver, copper, or zinc nitrates. The loaded zeolite particles were added to EVA through melt mixing. The prepared composite samples were then compression molded to obtain thin films with a thickness of about 0.1 mm. X‐ray diffraction experiments and scanning electron microscopy revealed successful synthesis of Mobil‐twenty‐two zeolite and its metal‐salt loading. Moreover, favorable distribution of the loaded zeolite in the polymer matrix was proved by scanning electron microscopy images. Also, stress–strain test unveiled that the addition of the zeolite particles enhances Young's modulus and tensile strength of the polymer while decreases its elongation at break. In addition, among the studied samples, the one containing 2 wt.% of silver‐loaded zeolite showed the highest Young's modulus of 105 ± 4.7 MPa. however, its modulus was only about 2% higher than that of the sample containing 2 wt.% of copper/zinc‐doped zeolite. Moreover, the two mentioned samples showed the highest elongation at break among the samples containing 2 wt.% of the loaded zeolites. Besides, the lowest observed elongation at break was 491% ± 16.2 belonging to the composite sample containing 2 wt.% of copper‐loaded zeolite. Furthermore, the film samples containing either of the loaded zeolite particles exhibited antimicrobial activity against Escherichia coli, Staphylococcus aureus, and Candida albicans, with maximum bacterial and fungal inhibitions of about 56% and 54% in the case of the film samples containing 2 wt.% of silver‐ and copper/zinc‐doped zeolite, respectively. Overall, it was concluded that copper and/or zinc‐loaded zeolites, the effects of which is comparable to that of silver‐loaded zeolite, have the potential for application as low cost additives to induce antimicrobial activity to EVA, while maintaining its beneficial mechanical properties.

Effect of Li1.3Al0.3Ti1.7(PO4)3 on semiconductive composites: Positive temperature coefficient (PTC) performance and inhibition of space charge injection

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. Li1.3Al0.3Ti1.7(PO4)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.

Comprehensive investigation into the thermal rheological behavior and relaxation characteristic of single/composite polymers in laminated glass

Polymeric interlayers are of significance for the structural capability of thin-walled laminated glass members both before and after glass fracture. Polymers present evident temperature and time dependence, which should be carefully assessed in the design process. To improve mechanical properties dependent on the temperature and time, novel interlayers including modified ethylene-vinyl acetate (PVE®) and composite PVE/PC (SGE®), have been developed along with the sound resistance of the interfacial adhesion to aging. In this work, dynamic mechanical thermal analysis tests were carried out to investigate the thermal rheological behavior and relaxation characteristic of polyvinyl butyral (PVB), ionomer (SentryGlas®, SG), PVE, PC and SGE. The results show that PVE and SGE follow the complex thermal rheological behavior as a result of the existence of two different types of relaxation transitions, whilst PVB, SG, and PC are thermorheologically simple materials. The arctangent function was introduced to describe the temperature dependence of PVB and SG. The relaxation modulus of polymers was subsequently derived based on the approximation equation and inverse Fourier transform. The results of the inverse Fourier transform indicate that vertical shift might need to be considered for PVE and SGE. The application of the approximation equation was assessed and its limitation was discussed. Finally, the relaxation characteristics of five polymers were described using the generalized Maxwell model based on the weighted least squares method.

Influence of UV exposure time and simulated marine environment on different microplastic degradation.

This study investigated the influence of environmental factors (UV radiation and salinity) in the degradative process of microplastics (MPs). MPs derived from polypropylene (PP), polystyrene (PS), and ethylene-vinyl acetate (EVA) were subjected to accelerated photodegradation while being submerged in distilled water or artificial seawater. Depending on the polymer, changes in surface properties, new functional chemical group formation and oxidative index, and thermal characteristics of samples were observed. After photodegradation experiments, EVA-MPs samples showed an increase in their thermal resistance, besides the changes in their surface. PP-MPs crystallinity index increased upon exposure to UV radiation. PS samples showed a higher carbonyl and hydroxyl index after 30h of UV exposure. The methodology exploited applies to any location in the world and can be comparable once considering the total ultraviolet index (UVI). The saline medium increases the crystallinity index of PP and EVA-MPs samples and intensifies the formation of new carbonyl and hydroxyl bonds in EVA-MPs samples. The results showed that several environmental factors should be considered in interpreting MPs photodegradation.

High-quality 3D printing of ethylene vinyl acetate with direct pellet-based FDM for medical applications: Mechanical analysis, energy absorption and recovery evaluation

Ethylene Vinyl Acetate (EVA) is a biocompatible and non-toxic copolymer known for its applications in medicine, drug delivery systems, and energy absorption. This paper presents a novel method for 3D printing EVA using the Fused Deposition Modeling (FDM) technique. By directly utilizing pellet-form EVA material and employing pneumatic pressure for extrusion, we addressed the issue of filament buckling commonly encountered in traditional filament-based printing. A custom-made pellet printer enabled direct feeding of polymer pellets. The mechanical properties, microstructure of the printed EVA parts was analyzed to evaluate the suitability of the direct pellet printing technique for producing high-quality EVA components. The results showed acceptable printing quality and favorable mechanical properties (about 1000% elongation at break and 6.59 MPa tensile strength). Additionally, a cyclic compression test was conducted, subjecting specimens to various strains (30%,80% and 120%) and assessing their compressive and energy absorption properties undergoing significant deformations. Observations reveal a noticeable decline in the mechanical properties after the first compression cycle. The mechanical properties tend to stabilize and reach a steady state from the second cycle onwards until the sixth cycle. Furthermore, a compression cyclic test with various strain rates conducted, investigated the functional performance of the printed EVA components in engineering and biomedical applications, considering the impact of strain rate. Observations indicate that lower strain rates tend to enhance the material's ability to withstand deformation before yielding. This study contributes to expanding the potential of EVA in additive manufacturing, particularly in biomedical and energy absorption systems.

Optimization of Autoclave Reactors to Improve Bearing Life Using the Taguchi Method and the Response Surface Methodology

Plastic pervasiveness in daily life has increased in tandem with population growth. Ethylene–vinyl acetate (EVA) is emerging as a popular compound for manufacturing plastic, which is obtained from ethylene and vinyl acetate synthesis. EVA is produced using autoclave reactors, which often encounter bearing damage under specific operating conditions. This research aims to optimize the parameters in autoclave reactors to enhance bearing life. The study focuses on two crucial factors: the number of impellers and the temperature, with bearing life as the response variable. Simulations using finite-element analysis were conducted to obtain the fatigue life of bearings and validated using real-time company data stating the damage of bearings within 80 days. The optimization process employed the Taguchi method (TM) and the response surface methodology (RSM). A comparison of these techniques revealed that temperature had the most significant influence on the response. Interestingly, both methods yielded the same optimal parameters: seven impellers and a temperature of 150 °C. The simulation results using these optimized parameters demonstrated a noteworthy 3.095% increase in bearing life compared to the initial design. The RSM outperformed the Taguchi method in accurately predicting response values with minimum prediction error under optimal conditions.

Influence of Multiple Modifications on the Fatigue Behavior of Bitumen and Asphalt Mixtures

Abstract The study included six bitumens, one unmodified and five modified, and their corresponding asphalt mixtures. The first bitumen was the base bitumen and further five variants were made by the authors using the same base bitumen and different combinations of modifiers which included styrene-butadiene-styrene (SBS), Fischer–Tropsch wax (FTW), ethylene vinyl acetate (EVA), reactive elastomeric terpolymer (RET), and natural asphalt (NA). The influence on the fatigue life of bitumen and asphalt due to modification, bitumen rheology, preload, water storage, and aging was studied. A new temperature range was developed—the fatigue-relevant temperature range (FRTR) for specifying fatigue test temperatures for bitumen and asphalt. A new methodology that includes preload and water storage was also done to study the active adhesion behavior between bitumen and aggregates and its influence on fatigue life. Overall, modifications showed positive influence on the fatigue behavior of bitumen and asphalt. Variants E (SBS and RET) and F (SBS and NA) showed the greatest positive influence with an increase in the fatigue life by 500% and 210% for bitumen and 200% and 375% for asphalt respectively. With water storage, the fatigue life reduced by 500% for unmodified asphalt and in the range of 333–1350% for modified ones. Due to aging, the fatigue life reduced from 700% for unmodified and between 700% and 2500% for modified asphalt mixtures.

Carbon fibers/nickel nanocomposite particles reinforced ethylene vinyl acetate stretchable conductive polymer: fabrication, microstructure, electrical and mechanical properties

Carbon fibers/nickel nanocomposite particles reinforced ethylene vinyl acetate stretchable conductive polymer: fabrication, microstructure, electrical and mechanical properties

Investigation on using graphite filler for 3D printing of flexible electrically conductive polymer by extrusion‐based additive manufacturing

AbstractThe rapid use of additive manufacturing (AM) in electronic industry identifies the need of flexible electrically conductive materials suitable for 3D printing. Challenges like buckling of flexible filament and complexity in addition of conductive fillers makes pellet‐based extrusion the most suitable alternative for part printing. In the present work, graphite powder is combined with ethylene vinyl acetate (EVA) to print flexible electrically conductive parts. EVA graphite composite with filler loading up to 30% has been investigated for its electrical conductivity and part printability. The composite made was found electrically conductive and suitable for part printing. The parts were printed on a CNC milling machine by using a retrofitted material extrusion tool with nozzle of 0.4 mm diameter and temperature range of 130–140°C. Parts were printed on a detchable heating bed placed on the milling machine setup. Samples of EVA with graphite filler by weight of 5%, 10%, 20%, and 30% were printed and were checked for electrical conductivity. When the filler content was increased from 10% to 20%, the electrical resistance of the composite was reduced by 62.6%. The presence and uniform dispersion of graphite flakes in the polymer matrix of EVA were guaranteed by the rheological and morphological characterization of the composite. Applications of 3D printable flexible electrically conductive parts lies in numerous domains including biosensors, wearable health monitoring devices, capacitors, field effective transistors, light emitting diodes, solar cells, and electronic displays.Highlights CNC milling machine‐assisted 3D printing is used for part printing. Graphite powder is combined with EVA pellets. Pellet‐based extrusion is used to print flexible parts. 3D printability of parts with resistivity 32.64 Ω‐cm was achieved.

Dielectric Properties of Composites Based on Ethylene Vinyl Acetate Filled with a Hollandite-Like Ceramic Material K1.5Co0.75Ti7.25O16

Polymer-matrix composites based on ethylene vinyl acetate (EVA) and KxCoyTi8 – yO16 solid solutionwith a hollandite-like structure (KCoTO(H)) are obtained and studied as promising materials for componentsof electronic devices. The filler is synthesized by modifying X-ray amorphous potassium polytitanate(PPT) K2O·nTiO2 (n = 4.3) in a CoSO4·7H2O solution under alkaline conditions, followed by thermal treatmentat 900°C. The structure of the synthesized material and the morphology of particles are studied by X-rayphase analysis (XPA) and scanning electron microscopy (SEM), respectively. KCoTO(H) is introduced in theEVA polymer matrix by mixing a preliminarily prepared polymer solution and a dispersion of filler powder inan appropriate solvent in amounts of 10, 20, 30, 40, and 50 vol %. The frequency behavior of the permittivity,dielectric loss tangent, and conductivity of the obtained composites is studied by impedance spectroscopy. Itis established that an increase in the KCoTO(H) content in the composite contributes to the growth of all thestudied dielectric characteristics of a relatively pure EVA polymer matrix in the entire frequency range of0.1 kHz–1 MHz (the maximum values are noted at a 50 vol % of the filler and f = 102 Hz: ε = 518, tanδ = 4,and σ = 1.35 S/cm).

Neural Network-Based Estimation of Flexural Performance for Polymer Permeable Concrete

Pervious concrete is increasingly used to reduce runoff water and improve water quality near pavements and parking lots, but highway pavement structures cannot use it due to its high porosity and reduced strength. To address the issue of lower flexural strength in permeable concrete, this study designs and conducts 11 different tests with varying mix ratios. The objective is to ensure that the resulting concrete satisfies both permeability and compression resistance requirements. The uniform test method is employed to measure the flexural strength of the concrete after a period of 28 days. This study employs neural networks to analyze the flexural performance of polymer permeable concrete by considering various input factors such as cement consumption, water consumption, STA (4.75 to 9.5 mm stones), STB (9.5 to 16 mm stones), VAE (vinyl acetate-ethylene) polymer content, and SAP polymer content. The objective is to optimize the mix proportion of polymer permeable concrete and identify a suitable ratio that satisfies the requirements of pavement structural flexural performance.

Thermal Image Analysis of Photovoltaic Panel for Condition Monitoring Using Hybrid Thermal Pixel Counting Algorithm and XGBoost Classifier

The use of thermal infrared imaging and the advancement of image processing techniques have developed fault diagnosis of Photo Voltaic (PV) panels without the need to incorporate expensive electrical detection circuitry. PV thermal image processing, supports in continuous monitoring of panels without disturbing the continuity of operation and mitigates the problem of manual inspection involved over a large area. The thermal pictures of photo voltaic panels are used to identify the nature of faults such as bypass diode, cell under fault condition, circuit which is under open condition, hot spot, polarization, Cracking, Corrosion, discoloring and delamination. An automatic PV Computer Aided Diagnosis (CAD) based condition monitoring systems with thermal image analysis is developed to identify and classify the different fault conditions such as Hotspot, Ethylene Vinyl Acetate (EVA) Discoloration, Delamination and Open Circuit. The proposed system involves a hybrid thermal pixel counting algorithm to identify the thermal patterns. The Extreme Gradient Boosting algorithm (XGBoost) is used to detect the numerical characteristics of the captured image thermal variations to support in classification. The experimental results show that the proposed Hybrid Thermal Pixel Counting (HTPC) Algorithm with XGBOOST Classifier gives better detection accuracy with improved computational speed.

Effect of sulfuric acid on cementitious composites containing ethylene-vinyl acetate and styrene-butadiene rubber

This study focuses on the influence of ethylene-vinyl acetate (EVA) and styrene-butadiene rubber (SBR) on the sulfuric acid resistance of ordinary Portland cement (OPC)-sulfoaluminate cement (SAC) repair mortar. Mortars were exposed to sulfuric acid solution for 60 or 180 days. The degradation kinetics, mineralogical as well as microstructural changes of these samples were analyzed. The results showed that EVA and SBR decreased the mechanical properties of OPC-SAC repair mortar but improved the mortar resistance to sulfuric acid attack. Both EVA and SBR could homogenize and refine the pore structure, reduce the number of connected and open pores, and fill the invasion channels of H+ and SO42−. The dual three-dimensional network structure formed by polymers in OPC-SAC mortar could delay the propagation of microcracks and limit the residual hydration and corrosion products around the core, forming a protective barrier.

Improvement of solder interconnections applied on back contact solar cells with low-temperature copper paste busbars

This work addresses the solderability and the reliability of n-type IBC ZEBRA cells with screen printed copper paste busbars. Improvement of the solderability by Sn60Pb40 solder alloy coated PV ribbon using an industrial automated IR stringer is reported. For qualification of the module reliability, climate chamber thermal cycling (TC) and damp heat tests (DH) were performed on mini modules with variations in material combinations: low temperature silver and copper pastes, each of them demanding dedicated soldering process parameters and two different encapsulation materials: polyolefin elastomers (POE) and ethylene vinyl acetate (EVA). All tested modules passed 3 x IEC TC and 2 x IEC DH, while the modules with EVA encapsulant passed DH 3000 as well. The copper paste metallized modules with EVA encapsulant showed no degradation in pseudo fill factor (pFF) and open circuit voltage (VOC), proving the statement that no copper diffuses into the silicon bulk.

Influence of Lamination Conditions of EVA Encapsulation on Photovoltaic Module Durability

Encapsulation is a well-known impact factor on the durability of Photovoltaics (PV) modules. Currently there is a lack of understanding on the relationship between lamination process and module durability. In this paper, the effects of different lamination parameters on the encapsulant stability due to stress testing have been investigated from both on-site production quality and long-term stability viewpoints. Rather than focusing on single stability factors, this paper evaluates lamination stability using a number of indicators including EVA (ethylene-vinyl acetate copolymer) curing level, voids generation, chemical stability, optical stability, and adhesion strength. The influences of EVA curing level on the stability of other properties are also discussed. It is shown that laminates stability increases with increasing curing level to an upper limit, beyond which leading to the formation of voids, reduced transmittance stability, discoloration, and unstable interfaces. A minimum gel content is identified but an upper limit should not be surpassed. The best range of gel content for the materials tested here is 84–90%. Samples with gel content below 70% show low chemical and optical stability, weak adhesion strength, and EVA flowing. Laminates with gel content over 92% are more likely to become yellow and are less stable in adhesion.

Effect of composition and structure of ethylene-vinyl acetate copolymer on its alcoholysis kinetics: A combined experimental and DFT study

The alcoholysis process of ethylene–vinyl acetate copolymer (EVA) is both important and complex. In this work, we conduct experimental and computational investigations to examine the alcoholysis kinetics and mechanism of EVA with an ethylene content if less than 50 mol%. Our findings indicate that the overall structure of EVA polymer chain has little effect on the alcoholysis rate. However, the local structure of the acetate group, particularly its association with the ethylene content, significantly affects the overall alcloholysis. To predict the influence of ethylene content on the overall rate constant, we propose an empirical model based on detailed kinetic studies of triads. Additionally, we discover a self-acceleration phenomenon in EVA alcoholysis, although it is less pronounced compared to polyvinyl acetate. Furthermore, we employed quantum chemical calculation using density functional theory (DFT) to confirm the effect of structure on EVA alcoholysis. Notably, we investigate, for the first time, the influence of neighboring hydroxyl group on self-acceleration phenomenon through theoretical calculations. This work offers valuable insight into EVA alcoholysis and may serve as a guide for exploring its mechanism and designing processes for producing EVA related polymer materials.

Chemical Delamination Applicable to a Low-Energy Recycling Process of Photovoltaic Modules

This work follows the current trend and need to ensure the best recyclability of retired materials. This paper focuses on experiments with chemical delamination of polymer layers on crystalline silicon photovoltaic cells. The aim of the study is to separate individual components of a PV module so that the components can be subsequently recycled with low energy demand. The ultimate goal is to separate whole silicon cells for reuse rather than for recycling. Several solvents (e.g., toluene, cyclohexane, tetrahydrofuran, and the commercial solvent U 6002 (a mixture of xylene and 2-ethoxyethylacetate)) were used to disrupt the polymer layers. The results showed toluene to be the most effective solvent, which acted the fastest and was able to disrupt the EVA (ethylene-vinyl acetate) film structure the most. The main problem of the investigated chemical delamination was the concurrent solvent absorption by the EVA film. This phenomenon was observed for all solvents. The absorption prevented the dissolution of the EVA film and changed its dimension, causing the adhering silicon cells to crack. While, as the final experiment shows, chemical delamination is, as done, a more energy-intensive process in terms of total energy consumption than the current chemical mechanical processes, we propose in the next development the recapture of toluene from the swollen EVA.

Rheological behaviors and foaming behaviors of crosslinked ethylene–vinyl acetate with polyfunctional monomers

AbstractTo produce ethylene–vinyl acetate (EVA) foams with a higher foaming ratio and stable cell size, the efficiency of the crosslinking reaction is required to conduct simultaneously with the blowing reaction. Hence, the multifunctional monomer trimethylolpropane trimethacrylate (TMP) as a crosslinking promoter and a crosslinking agent dicumyl peroxide are used together as a crosslinking system to EVA foaming, when chemical blowing agent azodicarbonamide (ADC) is used. The TMP concentration of approximately 1.0 phr (per hundred resin) is most effective for balancing the expansion ratio and fine cell size. In the SEM diagram and expansion ratio results, it can be found that when the concentration of TMP ranges from 0 to 1.0 phr, the cell mean size is reduced from 360.3 to 140.5 μm and the expansion ratio is reduced from 13.6 to 9.1 at 170°C. The results of time‐sweep experiment of thermogravimetric analysis (TGA) show that the foaming time of ADC in the melt increases with the addition of TMP. Capillary rheometer and rotational rheometer tests show that the viscosity and the crosslinking efficiency of the melt are improved with the TMP addition. The curing time has been reduced from 2.93 to 2.22 min for 170°C.

The role of paraffin wax on the properties and printability of ethylene vinyl acetate-based feedstocks for alumina fused filament fabrication

Fused filament fabrication (FFF) is a versatile and inexpensive additive manufacturing (AM) technique for fabrication of complex shaped ceramic structures. The composition of the binder phase in ceramic-filled feedstock is crucial in determining its rheological behaviour during processing as well as the ability to obtain a defect-free part following debinding and sintering. In this study, the effect of paraffin wax (PW) addition to alumina feedstock with ethylene vinyl acetate (EVA) binder, on feedstock preparation, printability, and debinding has been investigated. The PW incorporation resulted in successful fabrication of a flexible filament with a bending (fracture) strain of 4±1 %. The addition of PW however did not have a significant impact on the debinding of the developed alumina filaments. The printed parts could only be successfully debinded up to 2 mm wall thickness. The subsequent sintering of the debinded parts resulted in a relative density of 98 %.