Properties Of Ethylene Vinyl Acetate Research Articles

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.

Preparation and Properties of Ethylene Vinyl Acetate Copolymer/Silica Nanocomposites in Presence of EVA-g-Acrylic Acid.

Here we report a facile approach to enhance the dispersibility of ethylene vinyl acetate copolymer (EVA)/silica nanocomposites (for the EVA/silica nanocomposites and interaction between silica nanoparticles (nanosilica) and EVA by adding EVA-g-acrylic acid (EVAgAA) as a compatibilizer, which was formed by grafting acrylic acid onto EVA chains with the aid of dicumyl peroxide). The above nanocomposites with and without EVAgAA were prepared by melt mixing in a Haake intermixer with different contents of silica and EVAgAA. Their structure and morphology were characterized by Fourier transform infra-red (FT-IR) spectroscopy, field emission scanning electron microscopy (FE-SEM), and the mechanical, rheological, dielectrical, and flammability properties of the nanocomposites were also investigated. The FT-IR spectra of the nanocomposites confirmed the formation of hydrogen bonds between the surface silanol groups of nanosilica and C=O groups of EVA and/or EVAgAA. The presence of EVAgAA remarkably increased the intensity of hydrogen bonding between nanosilica and EVA which not only enhanced the dispersion of nanosilica in EVA matrix but also increased the mechanical, viscosity and storage modulus of EVA/silica nanocomposites. In addition, the flammability of EVA/silica nanocomposites is also significantly reduced after the functionalization with EVAgAA. However, the mechanical properties of EVA/silica nanocomposites tended to level off when its content was above 1.5 wt.%. It has also been found that the dielectric constant value of the EVA/EVAgAA/silica nanocomposites is much lower than that of the EVA/silica nanocomposites, which is another evidence of the hydrogen bonding formation between EVAgAA and nanosilica.

Preparation and Properties of Ethylene-vinyl Acetate/linear Low-density Polyethylene/Graphene Oxide Nanocomposite Films

Ethylene-vinyl acetate-based nanocomposites with 18 and 28 wt% vinyl acetate were prepared via solution casting method. To improve the mechanical and barrier properties of ethylene-vinyl acetate, linear low-density polyethylene, and graphene oxide were introduced to matrix. The morphological studies indicated that the graphene oxide diffraction peak disappeared in all prepared nanocomposites, probably due to its exfoliation; also proper dispersion and good interaction between nanofillers and polymer matrix were achieved. By introducing low amount of graphene oxide into the matrix, the mechanical and thermal properties and oxygen permeability were improved especially for those with 28 wt% vinyl acetate monomer.

Foaming and Damping Properties of Ethylene Vinyl-Acetate Copolymer/Polylactic Acid Blends

With ethylene vinyl-acetate copolymer (EVM) and polylactic acid (PLA) blends as the matrix, dicumyl peroxide (DCP) as the curing agent and azodicarbonamide (AC) as the foaming agent, EVM/PLA foamed blends were prepared by compression molding. The effects of different amounts of AC, DCP, and silica, as well as varying foaming time, on the cell structure and damping properties of the EVM/PLA-foamed blends were examined by scanning election microscopy (SEM) and dynamic mechanical analysis (DMA). The results showed that the cell size and damping properties varied little with increasing AC content in the compounds; however, the cell size declined slightly as DCP increased and the damping properties rose slightly, exhibiting an optimum set of properties at 5 phr of DCP. The cell size declined dramatically and damping increased significantly as the foaming time was increased. Moreover, both suddenly increased after 5 min foaming. It was found that the damping properties of the foamed materials increased with decreasing cell size and increasing number of cells. The cell size also decreased and damping properties increased as the silica content was increased. The silica interacted more strongly with EVM than with PLA.

Enhancement in the Electrical and Thermal Properties of Ethylene Vinyl Acetate (EVA) Co-Polymer by Zinc Oxide Nanoparticles

EVA/ZnO nanocomposites of 1%, 2% and 4% ZnO were fabricated by direct probe sonicator method. The ZnO nanopowders were prepared by solvothermal method. As the particle size of the filler incorporated to the polymer matrix decreases, the properties of the polymer-filler interface show dominance over its bulk properties. The dielectric constant and dielectric loss of the composites at ambient temperatures are found to decrease with increasing frequency. The thermal analysis using TGA-DTA is also performed and it is found that the thermal stability of the nanocomposites increases with increasing the filler concentrations. The thermal parameters such as thermal diffusivity (α) and thermal effusivity (e), the thermal conductivity (k) and heat capacity (Cp) were studied using photopyroelectric technique. The band gap of the samples was also determined and found to decrease with increasing filler concentrations. The tensile strength and peel strength of the samples were also investigated and it is found to increase with small inclusion of filler material.

An Accurate Thermoviscoelastic Rheological Model for Ethylene Vinyl Acetate Based on Fractional Calculus

The thermoviscoelastic rheological properties of ethylene vinyl acetate (EVA) used to embed solar cells have to be accurately described to assess the deformation and the stress state of photovoltaic (PV) modules and their durability. In the present work, considering the stress as dependent on a noninteger derivative of the strain, a two-parameter model is proposed to approximate the power-law relation between the relaxation modulus and time for a given temperature level. Experimental validation with EVA uniaxial relaxation data at different constant temperatures proves the great advantage of the proposed approach over classical rheological models based on exponential solutions.

Decomposition mechanism of fire retarded ethylene vinyl acetate elastomer (EVA) containing aluminum trihydroxide and melamine

The objective of this study is to evaluate the influence of aluminum trihydroxide (ATH) and melamine (MEL) mixture on the flame retardant and smoke release properties of ethylene vinyl acetate (vinyl acetate content of 60 wt%, EVA). The fire retardant properties were evaluated by mass loss calorimetry (MLC), limiting oxygen index (LOI) and UL-94. A home-made smoke test was developed to evaluate the smoke release of the material in a given scenario. It was found that the addition of ATH to EVA leads to improved fire retardant properties and reduced smoke release. Partial substitution of ATH by MEL at different ratios resulted in better results in MLC for a ratio of ATH:MEL of 5:1 and 10:1. Moreover, a lower quantity of smoke was released for EVA–ATH–MEL materials during material decomposition.A ratio of ATH:MEL of 5:1 was found to be the most promising. It was also shown that EVA–ATH–MEL ignited at shorter time in MLC test but longer ignition time in smoke test in comparison to EVA–ATH which is due to different test conditions. To understand the role of melamine on material properties, the degradation pathway of EVA–ATH–MEL was analyzed in details. The dispersion of the additives was examined by scanning electron microscopy (SEM) showing that all additives are homogenously dispersed in the matrix. In the next step the pyrolytic decomposition was investigated using thermogravimetric analysis (TGA) and pyrolysis-gas chromatography–mass spectrometry (py-GCMS). The decomposition of EVA–ATH–MEL was then analyzed in the gas phase using MLC coupled with a Fourier transform infrared spectrometer (MLC–FTIR) and in the condensed phase using solid state nuclear magnetic resonance (NMR) of 13C and 27Al. It was concluded that the additives protected the EVA both by a gas and condensed phase mechanism. The endothermic decomposition of ATH has a cooling effect and dilutes the fuel through release of water in the gas phase. Moreover, in the condensed phase, EVA–ATH–MEL is protected through formation of a char acting as barrier slowing down heat and mass transfer compared to EVA–ATH. Ignition at shorter times of EVA–ATH–MEL in comparison to EVA–ATH was found to be due to higher amount of flammable gases in the gas phase before ignition.

Effect of surfactant on EG dispersion in EVA and thermal and mechanical properties of the system

ABSTRACTThe influence of expanded graphite (EG) and sodium dodecyl sulfate (SDS) modified EG on the structure, thermal stability, and mechanical properties of ethylene vinyl acetate (EVA) was investigated in this study. The EVA filled with EG platelets, with and without anionic SDS modification, was prepared by melt mixing using a Brabender Plastograph mixer. The extent of dispersion and morphology of the composites were characterized using scanning electron microscopy (SEM), optical microscopy (OM), and X‐ray diffraction (XRD). The optical microscopy results show better distribution of the modified EG platelets in the EVA matrix, while the SEM results show an improved interfacial adhesion between the polymer and the SDS‐EG particles. Both the EVA18 copolymer and the EG platelets have monoclinic phases, and both EG and SDS do not seem to have any influence on the melting and crystallization behavior of the EVA18. The addition of EG enhanced the thermal stability of EVA18, and this stabilizing influence was further improved when the EG was treated with SDS. All the tensile properties of EVA/EG improved after surface modification. The storage modulus of EVA generally increased with increasing both the unmodified EG and the SDS modified EG content. There was a shift in the Tg to higher temperatures with an increase in both the EG and modified EG content. The α‐relaxation peak in the SDS modified EG curves was less intense than the β‐relaxation peak, even for the untreated EG composites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41352.

Effect of Electron Beam Irradiation on Mechanical and Thermal Properties of Ethylene Vinyl Acetate/Polyamide 6/High Density Polyethylene Nanocomposite

The effect of electron beam irradiation on mechanical properties of Ethylene vinyl acetate (EVA) with polyamide 6/high density polyethylene/HDPE-g-MAH and montmorillonite (MMT) were prepared by melt blending the characterization were investigated. The composites were characterized by Fourier Transform Infrared (FTIR) spectrophotometer and Thermogravimetric Analyzer (TGA) The samples were cross-linked by electron beam and irradiated at the dosage range of 0-200 kGy and 3.0 MeV. The mechanical properties of the samples which are tensile test and flexural test were measured by universal tensile machine whiles hardness was measured using Rockwell hardness tester. The gel content was performed to determine the formation of crosslinking and it showed improvement with increase dose up to 150 kGy. The result shows the increasing of tensile strength, tensile modulus, and hardness at the dosage 150 kGy but slightly decline at dose up to 200 kGy. Meanwhile TGA test showed that both irradiated and unirradiated samples have same trend characterization but irradiated samples are slightly more thermal stability. As a conclusion the electron beam irradiation enhance mechanical and thermal properties of ethylene vinyl acetate/polyamide 6/high density polyethylene nanocomposite.

Mechanical Ageing Protocol Selection Affects Macroscopic Performance and Molecular Level Properties of Ethylene Vinyl Acetate (EVA) Running Shoe Midsole Foam

Existing attempts to evaluate footwear via cyclic compression fail to sufficiently represent biofidelic force-time curves or provide the underlying mechanism of EVA foam fatigue. A uniaxial biofidelic waveform was compared to a sine wave of the same frequency to examine differences in (1) net displacement, (2) absorbed energy, and (3) peak force from ASTM F1614. A non-destructive molecular-level technique (ATR-FTIR) recorded differences in hydroxyl, ester, and unsaturated moieties due to EVA degradation. It was concluded that (1) biofidelic waveforms may better simulate human running, (2) material degradation is discernible, and (3) inferences regarding polymeric degradation and macroscopic performance require further investigation.

Technofunctional Properties of Films Made From Ethylene Vinyl Acetate/Whey Protein Isolate Compounds

One challenge faced by the plastics industry is that crude oil will become scarcer and more expensive in the future. Furthermore, an increase in plastic waste is leading to a strongly growing demand for sustainable alternatives to traditional, crude oil-based polymers in the packaging sector. The aim of this study was to investigate the influence of the incorporation of whey protein isolates (WPIs) on the technofunctional properties of ethylene vinyl acetate (EVA) films. The compounding EVA with WPI was conducted in a co-rotating twin-screw extruder at varying processing temperatures. WPI and hydrolysed WPI with a degree of hydrolysis of 10% were used up to 35% (w/w) as filler. The tensile strength and elongation at break of the resulting EVA-based films decreased significantly with increasing filler content. Because of the hydrophilicity of WPI, the water vapour permeability of the films increased. Advantageously, the oxygen barrier was enhanced by 50–80% compared with that of pure EVA films, which offered the potential of using whey proteins as a filler in compounds for packaging materials for their oxygen barrier properties. In addition, this study provides a promising perspective on the thermoplastic processing of whey protein formulations in the future. Copyright © 2013 John Wiley & Sons, Ltd.

Effect of zinc borate on flammability/thermal properties of ethylene vinyl acetate filled with metal hydroxides

In this work, zinc borate was used as a flame retardant in ethylene vinyl acetate/magnesium hydroxide or aluminum hydroxide flame-retardant formulations. High content zinc borate leads to significant improvements of flame retardancy through limiting oxygen index, UL-94 and cone calorimeter experiments. The protective char formation revealed significant structural modifications due to the presence of zinc borate. It was demonstrated that during polymer heating, aluminum hydroxide and magnesium hydroxide decomposed to Al2O3 and MgO which resulted an increase in ignition time. Moreover, formation of Al2O3 or MgO in situ from aluminum hydroxide or magnesium hydroxide during polymer combustion is the first event. Concurrently, zinc borate degraded and formed a vitreous protective coating, which yielded the substrate with an efficient char which acted as a physical barrier and a glassy cage for better protection of polymer substrate.

Tensile, rheological properties, thermal stability, and morphology of ethylene vinyl acetate copolymer/silica nanocomposites using EVA-g-maleic anhydride

In this article, we present a study on the properties of ethylene vinyl acetate copolymer/silica nanocomposites prepared in absence and presence of EVA-g-maleic anhydride as a compatibilizer between silica nanoparticles and ethylene vinyl acetate matrix. A series of ethylene vinyl acetate/silica nanocomposites with different contents of silica nanoparticles were prepared by solution method. EVA-g-maleic anhydride with 0.5 wt% maleic anhydride groups was added to all ethylene vinyl acetate/silica nanocomposites. Fourier transform infrared, field emission scanning electron microscopy, rheology behavior, and thermogravimetry analysis were used to characterize the structure, morphology, rheological, and thermal properties of the nanocomposites, respectively. The Fourier transform infrared spectra and field emission scanning electron microscopy micrographs showed that the hydroxyl groups on the surface of silica nanoparticles interact with maleic anhydride groups in EVA-g-maleic anhydride and lead to a finer dispersion of individual silica nanoparticles in the ethylene vinyl acetate matrix. The rheological properties and thermal stability of ethylene vinyl acetate/silica nanocomposites were significantly increased after adding EVA-g-maleic anhydride into the nanocomposites. Mechanical properties including tensile strength and elongation at break of the nanocomposites were mainly affected by the content of silica nanoparticles. For the tensile strength as well as elongation at break of the nanocomposites, a maximum value was observed at the content of 0.5 wt% of silica nanoparticles. The addition of EVA-g-maleic anhydride into ethylene vinyl acetate/silica nanocomposites resulted in a further improvement of mechanical properties of the nanocomposites.

Electrical and Mechanical Properties of Ethylene Vinyl Acetate Based Composites

In this study various composites based on the commercial ethylene vinyl acetate polymer matrix and multiwalled carbon nanotubes were prepared by casting from solution in the form of thick films. The degree of dispergation of carbon nanotubes in the polymer matrix was examined by scanning electron microscopy. Electrical conductivity and mechanical properties of those composites were investigated. It was observed that the electrical conductivity of composites increases with an increase of multiwalled carbon nanotubes content. The mechanical properties of composites were only slightly changed when compared with properties of neat ethylene vinyl acetate matrix.

Linear and non-linear viscoelastic properties of ethylene vinyl acetate/nano-crystalline cellulose composites

This paper reports on the melt rheological properties of ethylene vinyl acetate containing between 0 and 10 wt.% of nano-crystalline cellulose (NCC). A complete set of rheological tests including frequency sweeps, shear transients, and uniaxial elongations was performed. Frequency sweeps showed that at low frequencies, a pseudo solid-like behavior was obtained for NCC concentrations higher than 5%. This behavior was related to hydrogen bonding between NCC particles and the creation of particle networks as the result of particle–particle interactions. For transient shear tests, all compositions presented a stress overshoot at high shear rates before reaching a steady state. It was found that the amplitude of this overshoot depends on both NCC content and shear rate. On the other hand, the time to reach the maximum was found to be highly shear rate dependent but concentration dependence was rather weak. For uniaxial extensional flow, higher extensional viscosity was observed with increasing NCC content. On the other hand, strain hardening was found to decrease with increasing NCC content.

Morphological, transport, and adsorption properties of ethylene vinyl acetate/polyurethane/bentonite clay composites

AbstractThe effect of polyurethane (PU) foam on the morphological and transport properties of ethylene vinyl acetate (EVA) with 9% vinyl acetate and the potential application of 3%bentonite/28.5% PU/68.5% EVA composites fabricated via the melt‐blending method in heavy‐metal extraction from water systems were investigated. EVA did not swell in water, whereas the PU/EVA blend attained a maximum percentage of deionized water uptake of 2.158 mol %. A 3% bentonite/28.5% PU/68.5% EVA composite blend successfully removed 90% of Pb2+ from an aqueous solution with an initial concentration of 30 mg/L, whereas 3% bentonite/97% EVA could only extract 7.323% of Pb2+ ions. Pb2+ adsorption was found to obey the Langmuir adsorption isotherm and pseudo‐second‐order kinetic model. Thermodynamic studies demonstrated that the adsorption was favorable at room temperature and the uptake of Pb2+ was mostly by physical adsorption, as also indicated by the value n = 2.449 (where n is an empirical parameter indicating transport mode) from the Freundlich adsorption isotherm. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Crosslinking and grafting ethylene vinyl acetate copolymer with accelerated electrons in the presence of polyfunctional monomers

In this study, we have studied the effects of polyfunctional monomers (PFMs) on physical properties of ethylene vinyl acetate (EVA) copolymer crosslinked with electron beam (EB) or peroxides. The PFMs used were triallylcyanurate, triallylisocyanurate, trimethylolpropane trimethacrylate, zinc diacrylate, and ethylene glycol dimethacrylate. Using PFMs has led to (1) optimum cure time t90 decrease from 19′25″ to 17′30″–18′45″, (2) scorch time increase from 2′ to maximum 3′45″, (3) increasing the crosslink density of peroxide or EB-cured systems by increasing the efficiency of productive radical reactions. The most efficient PFM for EVA copolymer blends has been triallylisocyanurate. Tensile strength and tear strength of samples crosslinked with EB for all irradiation doses are significantly better than those obtained for samples crosslinked with peroxides (differences up to 190%). The results show that EB irradiation gave the best results

Mechanical, Thermal and Electrical Properties of Ethylene Vinyl Acetate Irradiated by an Electron-Beam

The effects of electron beam irradiation of (ethylene vinyl acetate) EVA containing 18% vinyl acetate was studied. The EVA sample was then irradiated by using 3 MeV electron beam machine at doses ranging from 120 to 360 kGy in air at room temperature and analyzed for mechanical, thermal and electrical properties. It was revealed by DSC analysis that the crystallinity of the electron-beam radiated EVA decreased slightly as verified by a marginal reduction in the densities and heats of melting. Thermal degradation of EVA occurred through two steps as shown by the thermogravimetric curve with maximum rates of 350 and 450°C, respectively. The results obtained from both gel content and hot set tests showed that under the irradiation conditions employed, the EVA sample cross-linked by the electron beam irradiation, and the degree of cross-linking in the amorphous regions was dependent on the irradiation dose. A significant improvement in the tensile strength of the neat EVA samples was obtained upon electron-beam radiation up to 210 kGy with a concomitant decline in elongation of break. Various electrical properties of EVA such as surface and volume resistance, breakdown voltage and dielectric constant were studied as a function of radiation dose. It was revealed that the surface resistance and volume resistivity of the EVA reaches a maximum at a 190 kGy dose of radiation. No considerable change of breakdown voltage and dielectric constant was observed with increasing irradiation dose. These studies suggest that radiation-cured EVA is more thermally and mechanically stable than pure EVA. Similarly, the results from the electrical properties revealed that surface and volume resistance are higher than pure EVA.

The Rheological and Mechanical Properties of Ethylene-Vinyl Acetate (EVA) Copolymer and Organoclay Nanocomposites

Ethylene-vinyl acetate copolymer, EVA (containing 28% vinyl acetate (VA)) and organoclay, tallow benzyl dimethyl ammonium ion with montmorillonite (ranging from 1 to 8 wt%) were melt processed in order to determine the relationship between the polarity of the polymer matrix and the organoclay structure on the properties of the resulting nanocomposites. The effect of clay loading on the rheological and mechanical properties of the nanocomposites is systematically investigated. The intercalated nanocomposites showed a dependence of the properties on the amount of clay loading. Increasing the amount of clay resulted in an improvement in tensile strength and elongation at break. In addition the EVA/clay nanocomposites displayed an enhancement of both storage modulus, E′, and loss modulus, E′′, at low frequencies. Addition of clay decreased the flow activation energy, thereby enhancing the polymer melt flow. Thus clay acted as a lubricant for the EVA polymer.