Properties Of Ethylene Vinyl Acetate Research Articles

Efficient and comprehensive recycling of valuable components from scrapped Si-based photovoltaic panels

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: HNO3 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 CH3COOH 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 CuSO4 with pH of 2 ∼ 3 to eliminate Pb and Sn. This article provides significant reference for the recycling of Si-based PV panels.

Rheological, morphological and solid-state viscoelastic properties of ethylene vinyl acetate copolymer/olefin block copolymer (EVA/OBC) blends

Rheological, morphological and solid-state viscoelastic properties of ethylene vinyl acetate copolymer/olefin block copolymer (EVA/OBC) blends

Lower Levelized Cost of Energy Achievement of Silicon Heterojunction Solar Modules with Low Water Vapor Transmission Rate Encapsulants

The damp‐heat (DH) degradation of silicon heterojunction (SHJ) solar modules leads to severe power loss, necessitating superior‐quality encapsulation materials. Herein, it is aimed to investigate the mechanical, thermal, and optical properties of ethylene vinyl acetate (EVA), polyolefin elastomer (POE), and thermoplastic polyolefin (TPO). TPO demonstrates the lowest water vapor transmission rate (WVTR) of only 3.14 g (m2·day)−1, which is approximately seven times lower than that of EVA. The Fourier transform infrared spectroscopy of EVA demonstrates a loss of the carbonyl group, revealing the formation of acetic acid under DH stress, which is not observed in POE and TPO. Both glass/back sheet and glass/glass (G/G) modules show a significant influence of encapsulant material on DH degradation. The maximum output power (Pmax) of the G/TPO/G single‐cell module maintains 96.6% of its initial value after 1000 h DH stress. After sealing the edge, the G/G commercial‐size modules encapsulated with lower WVTR encapsulants display excellent DH reliability, and Pmax degrades <4.8% after 3000 h of DH stress. The predicted levelized cost of energy (LCOE) decreases ≈0.11 US cents/(KW h), which boosts additional power generation and illustrates the remarkable potential for the SHJ solar modules meeting the requirements of reliable, sustainable, and low‐LCOE systems.

Effect of Hemp Hurd Biochar and Humic Acid on the Flame Retardant and Mechanical Properties of Ethylene Vinyl Acetate

In this work, the combination of biochar produced through a pyrolytic process of hemp hurd with commercial humic acid as a potential biomass-based flame-retardant system for ethylene vinyl acetate copolymer is thoroughly investigated. To this aim, ethylene vinyl acetate composites containing hemp-derived biochar at two different concentrations (i.e., 20 and 40 wt.%) and 10 wt.% of humic acid were prepared. The presence of increasing biochar loadings in ethylene vinyl acetate accounted for an increasing thermal and thermo-oxidative stability of the copolymer; conversely, the acidic character of humic acid anticipated the degradation of the copolymer matrix, even in the presence of the biochar. Further, as assessed by forced-combustion tests, the incorporation of humic acid only in ethylene vinyl acetate slightly decreased both peaks of heat release rate (pkHRR) and total heat release (THR, by 16% and 5%, respectively), with no effect on the burning time. At variance, for the composites containing biochar, a strong decrease in pkHRR and THR values was observed, approaching -69 and -29%, respectively, in the presence of the highest filler loading, notwithstanding, for this latter, a significant increase in the burning time (by about 50 s). Finally, the presence of humic acid significantly lowered the Young's modulus, unlike biochar, for which the stiffness remarkably increased from 57 MPa (unfilled ethylene vinyl acetate) to 155 Mpa (for the composite containing 40 wt.% of the filler).

A Systematic Investigation on the Influence of Intumescent Flame Retardants on the Properties of Ethylene Vinyl Acetate (EVA)/Liner Low Density Polyethylene (LLDPE) Blends.

Because of their high filler loadings, commercial-grade clean flame-retardant materials have unstable mechanical properties. To address this issue, intumescent polymers can be used to develop clean flame retardants with very low levels of smoke and toxicity generation. An intumescent flame retardant (IFR) system composed of red phosphorus (RP), zinc borate (ZB), and a terpolymer of ethylene, butyl acrylate, and maleic anhydride (EBM) was used to prepare EVA (ethylene-vinyl acetate) and EVA/LLDPE (linear low-density polyethylene) composites; their mechanical and flammability properties were systematically investigated. The limiting oxygen index (LOI) of the EVA/LLDPE (as base material) composite containing RP and ZB mixed with nonhalogenated flame retardant, mainly magnesium hydroxide (MH) and coadditives, including processing aids and thermal stabilizers, was established. RP was found to have little effect on the tensile properties of EVA/LLDPE 118W/120 phr flame-retardant (MH + RP) composites. There was a minute difference in the effective trend of RP between tensile strength and elongation at break. Following the addition of ZB, the elongation at break of the composites gradually decreased with increasing RP content and then leveled off when the RP content was over 10 phr. Mechanical properties (elongation at break and tensile strength) can be best maintained at below 10 phr content of RP. The mechanical properties decreased with lower amounts of EBM content. In addition, flame retardancy increased when the EBM content decreased. The findings further revealed that MH and RP have poor compatibility, yielding poor mechanical properties. The LOI greatly increased with RP content, even though the total content of flame retardants (main + intumescent flame retardant) was the same in all formulations. Only over 5 phr RP content formulations passed V-0 of the UL-94 test. When under 5 phr, the RP content formulations did not pass V-0 of the UL-94 test.

Structural, thermal, mechanical and viscoelastic properties of ethylene vinyl acetate (EVA)/olefin block copolymer (OBC) blends

In this study, ethylene vinyl acetate and olefin block copolymer (OBC) blends were prepared by melt-compounding. The effect of vinyl acetate (VA:12 and 28 wt%) and OBC (10–50 wt%) content on the morphological, thermal, and mechanical properties of EVA/OBC blends were studied in detail. Short-term flexural creep tests were also reported to investigate the time-dependent behavior of the blends. Non-isothermal crystallization results showed that, fractionated crystallization around 75C was observed in EVA (28%) blends. The creep study showed that the creep behavior of the blends significantly improves with the addition of OBC. The four-element Burgers model and the two parameter power law (Findley’s) model were fitted creep curves of the blends well. The addition of OBC promoted significant gains in terms of the mechanical and solid-state viscoelastic properties.

Basalt Fiber Modified Ethylene Vinyl Acetate/Magnesium Hydroxide Composites with Balanced Flame Retardancy and Improved Mechanical Properties.

In this study, we selected basalt fiber (BF) as a functional filler to improve the mechanical properties of ethylene vinyl acetate (EVA)-based flame retardant materials. Firstly, BF was modified by grafting γ-aminopropyl triethoxysilane (KH550). Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscope (SEM), and energy dispersive X-ray spectroscopy (EDS) were used to comprehensively prove the successful modification of the BF surface. Subsequently, the modified BF was introduced into the EVA/magnesium hydroxide (MH) composites by melt blending. The limiting oxygen index (LOI), UL-94, cone calorimeter test, tensile test, and non-notched impact test were utilized to characterize both the flame retardant properties and mechanical properties of the EVA/MH composites. It was found that the mechanical properties were significantly enhanced without reducing the flame retardant properties of the EVA/MH composites. Notably, the surface treatment with silane is a simple and low-cost method for BF surface modification and the pathway designed in this study can be both practical and effective for polymer performance enhancement.

Effect of Mixing Method on Properties of Ethylene Vinyl Acetate Copolymer/Natural Rubber Thermoplastic Vulcanizates.

Thermoplastic vulcanizate (TPV) has excellent elastomeric properties and can be reprocessed multiple times. TPV is typically produced by using the dynamic vulcanization (DV) method in which rubber is crosslinked simultaneously with thermoplastics. Peroxide-crosslinked TPV can increase the compatibility between rubber and thermoplastics but loses its reprocessability due to excess crosslinking in the latter. In this work, we overcome this obstacle by using a two-step mixing method to prepare fully crosslinked elastomers of ethylene vinyl acetate copolymer (EVA) and natural rubber (NR). Each sample formulation was prepared with three different mixing methods for comparison: NR-DV, Split-DV, and All-DV. For NR-DV, NR was crosslinked prior to the addition of EVA together with the thermal stabilizer (TS). For Split-DV, a small amount of EVA and NR was crosslinked prior to the addition of EVA and TS. In the All-DV method, EVA and NR were crosslinked, and then TS was added. The appearance and processability of the samples were affected by the degree of crosslinking. NR-DV showed a non-homogeneous texture. Although the samples of the All-DV method appeared homogeneous, their mechanical and rheological properties were inferior to those of the Split-DV method. The mechanical properties of the Split-DV samples were not significantly changed after reprocessing 10 times. Therefore, Split-DV is the preferred method for TPV production.

Effect of electron beam irradiation on the thermal and mechanical properties of ethylene-vinyl acetate copolymer/polyamide blends

The effect of electron beam (e-beam) irradiation on the thermal and mechanical properties of ethylene-vinyl acetate copolymer/ternary polyamide (EVA/tPA) blends was studied. The e-beam irradiation was carried out over a range of dose from 50 kGy to 500 kGy with trimethylolpropane trimethacrylate (TMPTMA) and triallyl isocyanurate (TAIC) as cross-linking coagents. With increasing irradiation dose, the gel fraction of the EVA/tPA blends increased significantly. After irradiated by e-beam at 500 kGy, the insoluble fraction of EVA/tPA blends with 3 parts per hundred rubber TMPTMA increased from 28% to 86%. The tensile strength of EVA/tPA/TMPTMA-3 (70/30/3) considerably increased up to 172% with a value of 10.01 MPa at 500 kGy due to an increase in cross-linking compared to the EVA/tPA/TAIC-3 (70/30/3) blend. However, the melting temperature and crystallization peak temperature of EVA/tPA blends decreased with increasing irradiation dose. Thermogravimetric analysis demonstrated that the irradiation cross-linking could improve the thermal stability of the EVA/tPA blends. The degradation kinetics of the EVA/tPA blends at elevated temperatures were studied using the Kissinger, Flynn–Wall–Ozawa, and Friedman methods. Irradiation cross-linked EVA/tPA blends exhibited a remarkable improvement in their oil resistance, with the identified improvement being most prominent in the EVA/tPA/TMPTMA-3 blend.

Optimal analysis for thermal conductivity variation of EVA/SCF composites prepared by spatial confining forced network assembly

In this paper, the influences of internal mixing, spatial confining forced network assembly (SCFNA) method, and the addition of dicumyl peroxide (DCP) crosslinker on the comprehensive properties of ethylene vinyl acetate copolymer/short carbon fiber (EVA/SCF) composite were investigated systematically. The results showed that both the increase of rotational temperature and the decrease of rotational speed during the internal mixing would do benefit to the maintenance of the SCF length and the enhancement of thermal conductivity (TC) of the EVA/SCF composite. During the SCFNA process, the distance between SCFs within the EVA/SCF composite trended to decrease with the increasing of compression degree. Thus, the thermal conductive networks would be compacted and the TC of the EVA/SCF composite can be enhanced by more than one order of magnitude while the material system kept unchanged in this process. Besides, we found the addition of DCP crosslinker would lead to a slight decrease in the melting and crystallization temperature of the EVA/SCF composite. The increase of DCP concentration would further result in the destruction of structural regularity of EVA matrix and the orientation difficulty of SCFs in the composite system.

The SÖderberg Socket 2.0: A Technical Note.

Transtibial prosthesis socket trim lines have remained fairly consistent over the past decade, and based on methods such as a supracondylar cuff suspension. However, with vacuum suspension methods, trim lines can change. An objective of this technical note was to inform practitioners how to fabricate a socket in a better way. A step-by-step fabrication guide is provided for the prosthetist. A unilateral transtibial amputee was selected for this technical note. We provide a detailed description of the different steps of fabrication as well as patient feedback. The fabrication involved fabrication of a vacuum socket using Pre-preg carbon fiber and anti-bacterial Ethylene-Vinyl-Acetate (EVA), as a proximal flexible brim. The properties of EVA and Pre-preg carbon fiber allow for fabrication of a transtibial socket with a flexible proximal brim. The new design resulted in greater comfort and increased range of motion in the patient studied. The patient subjectively noted enhanced squatting and cycling capabilities while using the updated socket and flexible proximal brim. This technical note presented a fabrication guide for a new style of socket and preliminary patient feedback. Clinical studies evaluating functional and biomechanical effects of this new socket design are needed.

Preparation and properties of nano zinc oxide doped ethylene vinyl acetate nanocomposites for solar cell encapsulation

Long term stability of the encapsulant is needed to resist heat, moisture, ultraviolet (UV) light and other weathering stresses. In this study, a new way of improving the properties of ethylene vinyl acetate (EVA) encapsulant was reported by doping a very small quantity (0.05 wt%, 0.1 wt% and 0.15 wt%) of nano Zinc Oxide (n-ZnO). EVA/n-ZnO composites were made by solvent casting process with addition of surface modified n-ZnO, followed by compression moulding to achieve thin films with thickness of 0.4 mm to 0.5 mm. Then, the intrinsic EVA and EVA/n-ZnO nano-composites were characterized to check the electrical, thermal, mechanical, and optical properties. The nano-composites exhibited superior electrical insulation than the intrinsic one. High temperature electrical insulation was remarkably good for the nano-composites. The effect of n-ZnO was also prominent in the mechanical behavior of encapsulants; tensile strength increased from 3.7 MPa (for intrinsic EVA encapsulant) to 15.3 MPa (for 0.1 wt% nano-composite). Elongation at break was also increased for nano-composites. EVA nano-composites were able to maintain low dielectric constant and low dissipation factor even at elevated temperature. Another one important criteria is light (UV and visible) transmission through the encapsulant. UV and visible light transmittance spectrum of EVA nano-composites were found better than the commercially available encapsulant. Therefore, n-ZnO was successfully doped on to the EVA matrix to provide better electrical, thermal, mechanical, and optical properties even at elevated temperature.

Effect of electron beam irradiation on the properties of EVA/EPDM blends

Effect of electron beam (EB) irradiation on the properties of ethylene vinyl acetate (EVA)/ethylene–propylene–diene monomer (EPDM) (50/50) blends was studied. The blends were firstly melt-compounded at 130°C followed with being irradiated using 4.0 MeV EB energy at doses ranging from 0 kGy to 200 kGy. It is found that the dosage of irradiation plays a key role in the properties of the blends. With the increasing dosage of irradiation, tensile strength and thermal stability were enhanced. The irradiation exerts a cross-linking effect on the blends, and the increase in density is responsible for the enhanced properties. Dynamic mechanical and thermal analyses and morphology indicate that irradiation does not play any negative role in the compatibility between EVA and EPDM. Hot set test reveals that irradiation could improve the heat deformation property of blends. Thus, it is reasonable and interesting to modify EVA/EPDM blends using EB irradiation to further increase its properties.

Thermo-mechanical recycling effects on morphology and properties of ethylene vinyl acetate copolymer/olive husk flour composites

The effects of thermo-mechanical recycling through repeated extrusion cycles on morphology and properties of neat ethylene vinyl acetate copolymer (EVA) and EVA/olive husk flour (OHF) composites (70/30 w/w) with and without ethylene–butyl acrylate–glycidyl methacrylate (EBAGMA) compatibilizer were investigated in a single screw extruder machine up to five repeated cycles. The study showed that no significant modifications in the properties of the virgin EVA/OHF composite were observed along the recycling and this stability was further enhanced in the presence of EBAGMA. Indeed after five repeated extrusion cycles, the chemical structure and properties of both uncompatibilized and compatibilized composites remained unchanged compared to the neat polymer, which was subjected likely to cross-linking, in the fifth cycle. Furthermore, SEM analysis showed a better dispersion of OHF particles in EVA matrix and a good filler–polymer interfacial adhesion, being, however, more pronounced for the compatibilized composite.

The Physical and Mechanical Properties of Ethylene Vinyl Acetate Modified Binder

During its service life, road pavement can easily crack, perforated or deformed. These damages happen as a result of low quality asphalt which indicated by its penetration index and stiffness value. 60/70 penetration asphalt modified by EVA polymer is expected to increase penetration index and stiffness value. Some experiments in the laboratory were carried out based on specified requirements and SNI-2011 asphalt testing procedures. The solid EVA was mixed with the liquid asphalt pen 60/70 at a medium to high temperature until it reaches 250 °C. During the mixing, this mixture was stirred for approximately ±15 minutes until homogeneous. These experiments consist of ductility test, penetration test, softening point test, flash point test, fire point test, specific gravity test, lose on heating test and asphalt stickiness to aggregate test. From the experiment, it can be concluded that the addition of 3.5% EVA in the asphalt pen 60/70 is generally acceptable based on the ductility value of SNI-2011 qualification. The addition of 3.5% give the ductility value of 130 cm, flash point of 300 °C, fire point of 310 °C, softening point of 54 °C, specific gravity of 1.020 gr/cc, asphalt stickiness to aggregate of 100% covered, and lose on heating of 0.037%. Nevertheless the experiment results in penetration value of 37.27 which doesn’t conform the qualification of asphalt pen 60/70. This penetration value resulting in penetration index value of -0.9. This shows that the asphalt resist to the temperature changing. Theoretical predictions of asphalt characteristics using BANDS 2.0 showed that the addition of EVA can increase the penetration index and the stiffness of the bitumen.

Mechanical, rheological and oxygen barrier properties of ethylene vinyl acetate/diamond nanocomposites for packaging applications

In this work, the effects of the surface-modified nanodiamond particles (NDs) on the barrier, rheological, mechanical and thermal properties of ethylene vinyl acetate (EVA) composites for the packaging applications were investigated. Fourier transform infrared spectroscopy, as well as thermal gravimetric analysis were employed to study the grafting of vinyltriethoxy silane (VTS) on the surface of NDs. Afterwards, EVA samples containing 0, 0.1, 0.5, 1, 1.5 and 2 wt% of surface-modified NDs were prepared by a two-stage process including the solution and injection processes. In order to evaluate the physicochemical, rheological, mechanical and thermal properties of the EVA/NDs samples, field emission scanning electron microscopy, contact angel measurement, rheometric mechanical spectroscopy, tensile test, differential scanning calorimetry, and thermogravimetric analysis were employed. The result showed a more uniform dispersion of modified NDs in the EVA matrix. Also, the oxygen permeability rate of EVA films in the presence of NDs was reduced remarkably. Furthermore, the mechanical characteristic and thermal stability of the EVA matrix were enhanced significantly in the presence of the modified NDs and the EVA/NDs nanocomposite films have this capability to use for the packaging applications.

Enhancement of flame retardancy and radiation shielding properties of ethylene vinyl acetate based radiation shielding composites by EB irradiation

Flame-retardant radiation shielding composites were processed using EVA matrix with magnesium hydroxide (Mg(OH)2), zinc borate (ZB) and bismuth oxide as filler materials. As filler content increased, the elongation at break and tensile strength of the materials decreased. Oxygen index (OI) of composites was higher than 27.2% when ZB content exceed 14 wt%. μm of materials gradually increased with the increase of bismuth oxide when tested by 137Cs. On the contrary, μm of materials decreased with the increase of bismuth oxide when tested by 60Co. Neutron shielding ratio of samples gradually increased with the increase of ZB when tested by Am-Be neutron source. Sample E with good comprehensive performances was selected and then modified by high energy EB irradiation. The mechanical properties, flame retardancy, and radiation shielding performances of modified composites were higher than those of the ordinary composites with the same filler mass fraction after being modified by electron beam irradiation with a dose of 175 kGy.

Effect of carbonized wood fiber and carbon black loading on density, tensile properties, electrical conductivity and swelling of ethylene vinyl acetate copolymer composites

Abstract Challenges faced to develop conducting polymer composites (CPCs) comprised of poor electro-active stability, control of the mobility, mechanical properties, presentation and concentration of bioactive molecules. Carbonized wood fiber (CWF) with diameter size of 110 µm was successfully produced from waste wood fiber grade B by using conventional furnace machine at 700°C in air atmosphere for 3 hours. In this study, the effect of CWF and carbon black (CB) on the properties of ethylene vinyl acetate (EVA) composites was studied. The samples were prepared by using brabender plasticoder at temperature 160°C with rotor speed of 50 rpm. The result indicated that EVA/CB composites showed higher density, void content, tensile strength, and electrical conductivity but lower elongation at break and swelling compared to EVA/CWF composites. Both composites showed increment in density, void content, and electrical conductivity, and reduced tensile strength, elongation at break, and swelling with increasing of filler loading in EVA composites.

Effect of intumescent compositions on flammable properties of ethylene vinyl acetate and polypropylene

SummaryAn intumescent flame retardant (IFR) system was prepared by 2 ways. Firstly, bis(2,6,7‐trioxa‐1‐phosphabicyclo[2,2,2]octane‐1‐oxa‐4‐hydroxymethyl) phosphonate methyl (bis‐PM) was synthesized and characterized by 1H nuclear magnetic resonance (NMR), 31P NMR, and Fourier transform infrared spectroscopies. This carbonization agent was mixed with melamine (ME), ammonium polyphosphate (APP), and pentaerythritol (PER) to constitute an IFR system. Secondly, an IFR system by reaction was prepared by reaction, and the presence of compositions in product was confirmed by 1H NMR and Fourier transform infrared. Both of systems enhanced the flammable retardation of ethylene vinyl acetate (EVA) and polypropylene (PP). Flammability and thermal behaviors of IFR‐EVA and IFR‐PP were investigated by vertical burning test (UL‐94 V) and thermogravimetric analysis. Results indicated that the IFR systems performed excellent flame retardancy and antidripping ability for PP. At 30 wt% loading, the optimum flame retardant formulations that are bis‐PM/ME: 4/1, bis‐PM/ME/PER: 3/1/1, APP/ME/PER: 3/1/1, and bis‐PM/ME/PER/APP: 1.5/1.5/1/1 give UL‐94 V‐0 rating. However, V‐0 rating results were only obtained for EVA when systems contain bis‐PM/ME: 4/1 and bis‐PM/ME/PER: 3/1/1. The char yield from decomposition of the IFR‐EVA and IFR‐PP has effects on the flame retardancy and antidripping behaviors of EVA and PP.

Pre-dispersing Process of Montmorillonite by Water and Toluene: Influence on Thermal Properties of Ethylene Vinyl Acetate / Montmorillonite Nanocomposites

Organanically modified montmorillonite (organo-MMT) was incorporated into ethylene vinyl acetate (EVA) copolymer to improve its thermal stability. A processing procedure, the so called ‘predispersing’ process of the organo-MMT was introduced prior to melt compounding process of both constituents in order to facilitate the nanofiller dispersion in the EVA matrix. Water and toluene were used as pre-dispersing medium, while magnetic stirring and ultrasonication were utilized as pre-dispersing method. The effects of pre-dispersing medium and method on thermal behaviour of neat EVA and EVA nanocomposites were analysed. It was anticipated that improvement in organo-MMT dispersion would enhance the matrix-nanofiller interactions, thereby the thermal properties of the resultant EVA/MMT nanocomposite. Based on thermal studies by thermogravimetric analysis (TGA), the organo-MMT nanofiller pre-dispersed by ultrasonication in water medium for 2 minutes (MMT(W)2m – u) resulted in most significant thermal stabilizing effect to the EVA copolymer. This was due to the significant improvement in the organo-MMT dispersion when the above mentioned pre-dispersing parameters were employed. Apparently, the result indicates that the high temperature behaviour of the nanocomposite can be affected by the strength of interphase interactions between the matrix and nanofiller which is also influenced by the dispersion of the organo-MMT.