Ethylene Vinyl Acetate Copolymer Research Articles

Study of thermal degradation mechanism of binders for ceramic injection molding by TGA-FTIR

Thermal debinding is the most widely employed method in ceramic injection molding. The gas evolution of binders and their mixture during degradation has been studied by TGA-FTIR. The results show that the thermal degradation of typical binders like ethylene vinyl acetate copolymer(EVA), polystyrene(PS), paraffin wax(PW) and stearic acid(SA) involves three main events of degradation: the first corresponds to the degradation of macromolecule binders into smaller molecules or carbon oxides; the second corresponds to the degradation of small molecular into carbon oxides; and the third corresponds to the oxidation of carbon residues to carbon oxides. The degradation of acrylic resin (AR) involves only one main event of degradation and it corresponds to the degradation of AR into acrylic ester small molecule. Mixture's 3D diagram verified that degradation products of binders are not changed with the mixing of binders. The TGA(DSC) curves of mixture suggest that the mixing of binders decreases the initial degradation temperature of some low molecular weight binders. But it also increases the degradation temperature of some polymer binders. The TGA(DTG) curves of feedstocks reveals that ceramic powders increase the temperature at the beginning of degradation due to a physical or chemical adsorption of ceramic powders on binders.

Voltage–current characteristics of high-density polyethylene conductive composites

The high-density polyethylene (HDPE) conductive composites filled separately with carbon fibers (CFs), ethylene-vinyl acetate copolymer (EVA), and three kinds of carbon blacks (CBs) (including different diameter, BET specific area, and DBP value) were prepared, to investigate the influence of the property, size, and content of the conductive fillers on the nonlinear voltage–current characteristics of the HDPE conductive composites. The results showed that the relationship between the electric current density and the electric field intensity of the three HDPE/CB composites including the HDPE/CF composites, the HDPE/CB/CF composites, and the HDPE/EVA/CB composites was nonlinear. The nonlinear conductivity index of the HDPE/CF composites was kept a low level comparing to the HDPE/CB composites, the HDPE/CB/CF composites, and the HDPE/EVA/CB composites. Moreover, the nonlinear conductive behavior mechanisms were discussed.

Nano/microfibers of EVA copolymer obtained by solution blow spinning: Processing, solution properties, and pheromone release application

ABSTRACTPheromones have been used for monitoring and control of insect pests in crops, reducing the use of pesticides. However, among obstacles for this technology to be more useful, is the control and time to release. In this way, this work aims the evaluation of the release of pheromones using micro/nanofibers of ethylene–vinyl acetate (EVA) produced by blow spinning. Solutions with 0.5–15 wt % EVA were prepared based on the solubility parameter of the copolymer. Fibers were obtained from solutions in the semidiluted concentration regime. Synthetic sex pheromones from the oriental fruit moth, Grapholita molesta and citrus leafminer Phyllocnistis citrella were incorporated into the micro/nanofibers. The morphology and structure of these fibers were evaluated employing field emission scanning electron microscopy and wide‐angle X‐ray diffraction. The fibers sizes (95–426 nm) were dependent on the feed rate of the solution. As a result, pheromone release has occurred linearly over 10 weeks, as determined by thermogravimetry analysis. The solubility parameter influences the amount incorporated in the fiber and the rate of pheromone release. The proposed fiber/pheromone system is interesting since it reduces the use of actives and can be used in several planting cycles and reused. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47647.

Development of metal hydroxide nanoparticles from eggshell waste and seawater and their application as flame retardants for ethylene-vinyl acetate copolymer (EVA)

Recently, calcium hydroxide and magnesium hydroxide nanoparticles have attracted a lot of research interest in different sectors: food, packaging, health, automotive construction and food application. In the present study, we report development of bio-material calcium hydroxide nanoparticles (Ceg-Ca(OH)2), obtained from chicken eggshell collected from the food industries as well as magnesium hydroxide nanoparticles obtained from seawater (Seaw-Mg(OH)2). The flame-retardant behavior of Ethylene-Vinyl Acetate copolymer (EVA) containing different blends of Ceg-Ca(OH)2 and Seaw-Mg(OH)2 nanoparticles has been evaluated using cone calorimeter. Our results showed the interest of combining both nanoparticles. In fact, the partial substitution of small Seaw-Mg(OH)2 content (10 wt%) by Ceg-Ca(OH)2 enables further reduction of pHRR from 251 to 206 kW/m2 without any reduction of the composite time to ignition (52 s). Furthermore, the partial substitution of 40 wt% Seaw-Mg(OH)2 nanoparticles by Ceg-Ca(OH)2 enables high flame retardant effect as well as the generation of cohesive residue.

Influenceof Vinyl Acetate Content on the Surface Hydrophobic Recovery of Ethylene Vinyl Acetate Copolymer after Plasma Modification

AbstractIn this paper, two kinds of ethylene vinyl acetate copolymers (EVA) with different vinyl acetate (VA) contents were modified by plasma technique. The surface hydrophobic recovery and the nanostructure of the samples were evaluated by water contact angle measurement and positron annihilation lifetime spectroscopy, respectively. The water contact angle results indicated that higher VA content would result in faster hydrophobic recovery after plasma modification. The positron annihilation results indicated that two kinds of EVA samples exhibited similar o‐Ps lifetime, and EVA with higher VA content showed higher o‐Ps intensity. The results implied that the faster hydrophobic recovery after plasma modification should be contributed to the easier relaxation of chain segments for the EVA with higher VA content.

Intumescent ethylene-vinyl acetate copolymer: Reaction to fire and mechanistic aspects

The concept of intumescence was applied to flame retard ethylene vinyl acetate copolymer (EVA). The paper examines two types of intumescence based on expandable graphite (EG, physical expansion) and on modified ammonium polyphosphate (AP760, chemical expansion). The incorporation of expandable graphite (EG) at relatively low loading (10 wt%) in EVA permits the reduction up to 65% of peak of heat release rate (pHRR) measured by cone calorimetry. The mode of action occurs via the formation of an expanded carbonaceous layer acting mainly as heat barrier limiting heat and mass transfer as evidenced by the temperature measurement as a function of time during cone calorimetry. The incorporation of small amount of ZnCO3 in EVA-AP760 enhances strongly the performance: pHRR was not reduced using the sole AP760 while it is decreased by 54% when only 2 wt% of AP760 is substituted by ZnCO3. A strong synergistic effect was therefore observed. Solid state NMR of 31P and 13C on cone residues prepared at different characteristic times evidenced the mechanism involved is the reinforcement of the protective char by the formation of phosphate glass limiting the creation of cracks and increasing the char strength.

Poly(lactic acid)/ethylene vinyl acetate copolymer blend composites with wood flour and wollastonite: Physical properties, morphology, and biodegradability

In the present study, poly(lactic acid) (PLA), a biodegradable plastic, was melt‐blended with five weight percentages (10–50 wt%) of ethylene vinyl acetate (EVA) copolymer, a non‐biodegradable plastic, having a vinyl acetate content of 19 wt% and a melt flow index of 530 g/10 min, on a twin screw extruder, followed by an injection molding. The blends at 10 and 20 wt% EVA revealed a noticeably increased impact strength and strain at break over the pure PLA, and the blend at 10 wt% EVA exhibited the highest impact strength and strain at break. The 90/10 (wt%/wt%) PLA/EVA blend was then selected for preparing either single or hybrid composite with wood flour (WF) and wollastonite (WT). The filler loading was fixed at 30 parts by weight per hundred of resin throughout the experiment, and the WF/WT weight ratios were 30/0, 20/10, 15/15, 10/20, and 0/30. The prepared composites were examined for their mechanical and thermal properties, melt flow index, flammability, water uptake, and biodegradability as a function of composition. All the composites showed a filler‐dose‐dependent decrease in the impact strength and strain at break, but an increase in the tensile and flexural modulus (optimal at 0/30 WF/WT) and tensile and flexural strength (optimal at 30/0 WF/WT) as compared with the neat 90/10 (wt%/wt%) PLA/EVA blend. In addition, the melt flow index, char residue, anti‐dripping ability, water uptake, and biodegradability of the composites were also higher than those of the neat blend. J. VINYL ADDIT. TECHNOL., 25:313–327, 2019. © 2019 Society of Plastics Engineers

Definition of the thermal and fire-protective properties of ethylene-vinyl acetate copolymer nanocomposites

To create a fire retardant coating that can be applied in the hydrocarbon fire, the nanocomposites of the ethylene-vinyl acetate (EVA) copolymer with montmorillonite (MMT), thermally expanded graphite (EG) are synthesized and their structure, physicochemical and thermal properties are studied. Using IR spectroscopy and X-ray phase analysis, it is found that the EVA nanocomposites with montmorillonite and nanographite obtained in solution and melt have the same structure. Thermal-oxidative degradation of the EVA copolymer and nanocomposites on its basis in the temperature range of 100–700 °C is investigated. It is proved that nanoclay and nanographite as a part of nanocomposites increase thermal characteristics of the original polymers. The thermal stability of the studied compounds increases in the series: polymer<polymer-EG<polymer-MMT <polymer-MMT-EG. It is shown that the presence of nanoparticles in the polymer matrix reduces the EVA thermal decomposition rate at a temperature above 450 °C and increases the coke residue mass after the destruction of the initial EVA copolymer at a temperature of 250 °C. The synergistic effect of the MMT/EG mixture on the processes of slowing down the thermal degradation of the EVA copolymer is found. The effect of organomodified montmorillonite and graphite in the EVA nanocomposites on the thermal destruction of the intumescent system of ammonium polyphosphate/melamine/pentaerythritol is studied. The synergistic effect of the mixture of clay and graphite nanoparticles in a hybrid nanocomposite is revealed. Synergism consists in increased fire resistance of metal structures by almost 20 % compared with the coating containing the polymer-nanoclay or polymer-nanographite nanocomposite. Based on the results obtained, the intumescent base of fire retardant paint for steel structures, which is recommended for use to increase the fire-resistance rating of metal in the hydrocarbon fire is developed

The Effect of Direct-to-Plant Styrene-Butadiene-Styrene Block Copolymer Components on Bitumen Modification.

Five types of material, styrene-butadiene-styrene block copolymer (SBS), ethyl-vinyl-acetate (EVA), naphthenic oil, maleic anhydride grafted ethylene-vinyl acetate copolymer (EVA-g-MAH) and butylated hydroxytoluene (BHT) were used as the raw ingredients for manufacturing direct-to-plant SBS in this paper. Thirteen kinds of direct-to-plant SBS with different EVA/SBS and naphthenic oil/SBS were prepared as well as the processes diagrammatic sketch of dispersion and swelling of direct-to-plant SBS modifier in bitumen were discussed. Microscopic images of direct-to-plant SBS modified bitumen with different components were obtained using fluorescence microscopy. The micro-images were analysed and quantified with MATLAB software. The influence of key components on the micro-morphology of direct-to-plant SBS-modified bitumen is discussed, followed with the tests on melting points and the melting indexes of direct-to-plant SBS with different EVA/SBS and naphthenic oil/SBS. The performances test of bitumen and bituminous mixture modified by these direct-to-plant SBS were also conducted. Results show that, with the ratio improvement of EVA/SBS or naphthenic oil/SBS, the number of the pixel dot number of area (SBS) in microscopic images increased. Enlargement of the pixel dot number of centre line elongate and the structure fineness was observed, indicating that the dispersion and swelling effect of the SBS modifier in bitumen had been improved. Meanwhile, the macro index, such as the melting point and melting index of direct-to-plant SBS, was also improved corresponding to the increase of EVA/SBS ratio or naphthenic oil/SBS ratio. With the addition of EVA or naphthene oil content, penetration and ductility of direct-to-plant SBS modified bitumen received gradual enhancement, but the softening point and viscosity were found out to be decreased. The high-temperature and low-temperature performances of direct-to-plant SBS modified bituminous mixture can be effectively improved by adding EVA or naphthenic oil. By meeting the required performances of direct-to-plant SBS, modified bitumen and bituminous mixture, the component of direct-to-plant SBS is recommended as, SBS:EVA:naphthenic oil:EVA-g-MAH:BHT is 1:0.1–0.5:0.05–0.2:0.03:0.05. For the compatibleness of SBS with different bitumen are different, necessary tests verification is recommended to be carried out prior to usage.

Improved Flame-Retardant and Ceramifiable Properties of EVA Composites by Combination of Ammonium Polyphosphate and Aluminum Hydroxide.

Ceramifiable flame-retardant ethylene-vinyl acetate (EVA) copolymer composites for wire and cable sheathing materials were prepared through melt compounding with ammonium polyphosphate (APP), aluminum hydroxide (ATH) and fluorophlogopite mica as the addition agents. The effects of ammonium polyphosphate, alumina trihydrate, and APP/ATH hybrid on the flame retardant, as well as on the thermal and ceramifiable properties of EVA composites, were investigated. The results demonstrated that the composites with the ratio of APP:ATH = 1:1 displayed the best flame retardancy and the greatest char residues among the various EVA composites. The tensile strength of the composites was 6.8 MPa, and the residue strength sintered at 1000 °C reached 5.2 MPa. The effect of sintering temperature on the ceramifiable properties, microstructures, and crystalline phases of the sintered specimen was subsequently investigated through X-ray diffraction, Fourier transform infrared, and scanning electron microscopy. The XRD and FTIR results demonstrated that the crystal structure of mica was disintegrated, while magnesium orthophosphate (Mg3(PO4)2) was simultaneously produced at an elevated temperature, indicating that the ceramization of EVA composites had occurred. The SEM results demonstrated that a more continuous and compact microstructure was produced with the rise in the sintering temperature. This contributed to the flexural strength improvement of the ceramics.

Shape Memory Properties of Melt-Blended Olefin Block Copolymer (OBC)/Ethylene-Vinyl Acetate Blends

The completely crosslinked shape memory polymer blends (SMPs) traditionally suffer from recycling problems due to their network structure. In this paper we describe the thermal, mechanical, and shape memory behavior of physical blends of OBC (Olefin block copolymer) and EVA (Ethylene-vinyl acetate copolymer), with and without modification of one or both of the components, prepared using a melt-blending method. These behaviors of the modified blends, based on maleated OBC (OBC-g-MA) and/or vinyltriethoxysilane (VTEOS) modified EVA, included OBC/EVA-g-VTEOS, OBC-g-MA/EVA, and OBC-g-MA/EVA-g-VTEOS blends; they were investigated to compare with the OBC/EVA blend. The SEM (scanning electron microscopy) observations showed that the compatibility of the silane and maleic anhydride modified OBC/EVA blends were better than that of the unmodified OBC/EVA blend. The crystallization temperatures of OBC and EVA in the modified blends were higher than those in the neat blend. The OBC-g-MA/EVA-g-VTEOS blend had the highest modulus and thermal stability of all investigated blend systems due to the numerous interactions between maleic anhydride and silane. The shape memory performance, as defined by the shape fixity ratio (Rf) and shape recovery ratio (Rr), was higher for the modified blends of one or both of the modified components than that for the OBC/EVA blend. These modified blends were readily reprocessible, like thermoplastic vulcanizates, and still retained shape memory behavior, in contrast with the fully crosslinked shape memory polymer blends; thus they were also improved in terms of the environmental aspects of processing.

Effect of both Modified &amp; Unmodified Nanosilica on Morphological and Thermal Properties of Model TPE Blend Systems

A comparative study between the modified and unmodified nanosilica to fine tune the morphological and thermal properties of a model low-density polyethylene (LDPE) – ethylene vinyl acetate copolymer (EVA) thermoplastic elastomer blend system is explored in this article. The nanosilica particles were melt-blended with the LDPE/EVA system through the variation of the sequence of addition. The blends were compression molded, and their morphological and thermal properties were evaluated. The incorporation of nanosilica particles produced a drastic improvement in thermal stability as compared to the control blend. The morphological studies clearly indicated that modified nanosilica had a homogeneous dispersion in the bi -component polymer matrix leading to strengthening of silica-polymer interface. Interestingly, after modification the sequence did not play a major role in affecting the morphology of this system. Overall, although the properties of the unmodified nanosilica filled blends are strong functions of the sequence of addition, but, interestingly, the properties of the modified nanosilica filled blends do not depend much on the preparation procedure.

Improvement in the Superhydrophobicity of Cellulose Aerogels Using Cationic Polymers

In this study, a cross-linked cellulose aerogel was first prepared using a cellulose wet-gel treated with a mixture of cationic poly (aminoamide)-epichlorohydrin and vinyl acetate ethylene copolymer. Following this, a cross-linked superhydrophobic cellulose aerogel was successfully fabricated using a simplified silanization process. The silane-coated cellulose aerogel exhibited an excellent oil absorption capacity (18 to 65 times the dry weight of the cellulose aerogel) without water absorption, and the recovered dimensions of the cellulose aerogel after compression were improved via the cationic polymer treatment. This material, thus, exhibits great potential as an oil absorbent.

EFFECTS OF MAGHNITE NANOCLAY MODIFICATION AND COMPATIBILIZATION ON THE PHYSICAL AND MORPHOLOGICAL PROPERTIES OF POLY(VINYL CHLORIDE)/POLY(ETHYLENE-CO-VINYL ACETATE) BLENDS

In this research work poly(vinyl chloride)(PVC), ethylene vinyl acetate copolymer (EVA), and Maghnite nanoclay (MGT) were used to prepare PVC/EVA nanocomposites. The MGT clay was intercalated with octadecyltrimethylammonium chloride (ODTMA) and grafted with γ-aminopropyltriethoxysilane (APTES). The blend nanocomposites were prepared through the melt mixing of PVC/EVA blend at a weight ratio of 50/50 (wt%/wt%) with 20 wt% of compatibilizer; ethylene vinyl acetate grafted with an alcohol (EVA-g-OH) and 3 wt% of modified MGT clay using a Brabender plastograph. The nanocomposites so prepared were characterized using X-ray diffraction, TGA/DTA, mechanical tests and SEM. The results showed that when PVC was blended with EVA, with the modified MGT and with the compatibilizer, synergistic effects in the thermal stability and mechanical properties were observed.

Synergistic effect of polydopamine-polyethylenimine copolymer coating on graphene oxide for EVA nanocomposites and high-performance triboelectric nanogenerators.

While the demand for lightweight high-strength nanocomposites is immense, their progress has been severely limited due to inferior filler dispersion and filler–matrix interface adhesion. This article reports a novel modification of graphene oxide (GO) encapsulated by the copolymer of polydopamine (PD) and polyethylenimine (PEI) via a Michael addition reaction, aiming to create robust ethylene vinyl acetate copolymer (EVA) nanocomposites even at very low amounts of filler loading by overcoming the above hindrances. It has been found that the addition of only 1.2 wt% modified GO (i.e., PD–PEI–rGO) increased the tensile strength, Young's modulus and storage modulus of EVA composites by 80%, 50% and 24%, respectively. These increments surpass many recent claims on relevant composites. Excellent molecular level dispersion was also observed from the fracture surface SEM images. Being amine-rich with high electron-donating capability and mechanically robust, the nanocomposite served as an outstanding tribopositive material, thereby generating 7.49 V and 4.06 μA output voltage and current, respectively, when employed in a triboelectric nanogenerator (TENG). The high electrical outputs led the device to light up 43 blue LEDs instantaneously upon hand pressing, demonstrating that the nanocomposite is indeed a promising candidate for harvesting green energy. Moreover, the nanogenerator displayed outstanding cyclic performance stability (even after 8000 cycles) and environmental durability.

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.

Quantitative Analysis for Estimating the Content Ratio of Ethylene Vinyl Acetate Copolymer (EVA)/Very Low Density Polyethylene (V-LDPE) Blended Foam

Recently, ethylene vinyl acetate (EVA) and very low density polyethylene (V-LDPE) blended foam (EVA/V-LDPE-foam) used in various industrial fields has been studied in order to improve the mechanical properties such as lightness and cushioning. The content ratio of EVA and V-LDPE was one of the important factors to control mechanical properties. The determination of the ratio of the above was desired from the view of quality control. The ratio could be determined through comparison between the content of vinyl acetate of non-linked EVA(VA wt%N) and EVA/polyethylene (PE) foam (VA wt%F). However, it was difficult to determine VA wt%N by the conventional analytical techniques. In this study, a trace amount of non-cross-linked EVA in the cross-linked foam is focused on the determination of VA wt%N. Separation of non-linked EVA was attempted by using solubility-difference between EVA and V-LDPE which were extracted from the foam to 10 vol% acetonitrile in chloroform solution. As a result, non-linked EVA was separated from non-linked components including a trace amount of V-LDPE by elution-time-difference. VA wt%N was estimated by Fourier-transform infrared spectroscopy (FT-IR) and the content ratio was determined through comparison between VA wt%N and VA wt%F.

Development of Pre-treatment Agent Based on Vinyl Acetate-Ethylene Copolymer Emulsion for Pigment Ink in Digital Textile Printing

Development of Pre-treatment Agent Based on Vinyl Acetate-Ethylene Copolymer Emulsion for Pigment Ink in Digital Textile Printing

Study the rheological properties of waxy oil with modified pour point depressants for the South Turgai oil field in Kazakhstan

This work describes the performance of poly(ethylene-co-vinyl acetate) (EVA) copolymer and modified poly(ethylene-co-vinyl acetate) (EVA-M) as pour point reducer. Commercially available EVA copolymer modified with sodium hydroxide in methanol. Partially hydrolyzed EVA was obtained and Fourier Transform InfraRed (FTIR) analysis of the modified EVA was recorded. The modified and unmodified EVA was used to crude oil of South Turgai, Kazakhstan, in order to improve the flowability of the crude oil. According to the rheological behavior of oils in the South Turgai, the findings showed that modified EVA lowered the dynamic viscosity greater compared to unmodified EVA and heat treatment. Dynamic viscosities and yield points of different oils with various temperatures with using EVA and EVA-M were studied systematically. Finally microphotograph of crystal structures two oils with using EVA and EVA-M, under same conditions, were compared and discussed.

Regulation of electrophysical properties of fireproof polymer compositions filled with hydromagnesite for cable products

The level of electrophysical properties of fireproof polymer compositions, depending on the influence of ingredients, has not been sufficiently studied. This is especially true of the effect of the modifier on the properties of the insulation and sheath of cable products. Therefore, the object of research is the electrophysical properties of fireproof composite materials: ethylene-vinyl acetate copolymer, filled with hydromagnesite. Composition of the copolymer with a melt flow index of 2.5 and 5 g/10 min, hydromagnesite with an average median particle diameter of 1.4 μm, aminosilanes with a dynamic viscosity of 2 MPa·s and 2.5 MPa·s are investigated. An isolation test apparatus, an insulation resistance meter, an AC bridge are used. Electrophysical characteristics are obtained, which allow to determine the composition that provides the optimal values for insulating materials and materials of cable sheaths with increased fire safety requirements. The methods of electrophysical studies are used to determine the effect of the properties of the ingredients of polymer compositions on the electrical strength, specific volume electrical resistance, the dielectric loss tangent, and dielectric constant. Electric strength increases when using the polymer matrix EVA-1 and modifier 1 from 21 to 40 kV/mm; when using the polymer matrix EVA-2 and modifier 2 from 22.5 to 42 kV/mm. The specific volume electrical resistance increases significantly for polymer compositions filled with hydromagnesite, using the polymer matrix EVA-1 and modifier 1. Its value increases from 1∙10 13 to 6.6∙10 14 Ohm cm. Using the polymer matrix EVA-1 results to reduce the dielectric constant. A significant decrease in this indicator from 4.1 to 3.6 is observed when using modifier 1 with a lower dynamic viscosity (2 MPa s). The tangent of dielectric loss angle also decreases from 0.013 to 0.0046 when using the modifier 1. It is advisable to use the results of the research to develop the composition of fireproof polymer compositions for cable products.