Filled Ethylene Vinyl Acetate Research Articles

Vulcanization kinetics and mechanical properties of filled ethylene-vinyl acetate copolymer rubber composites

Abstract The vulcanization reaction of ethylene vinyl acetate copolymer (EVM) rubber is fast, resulting in poor processing safety. EVM is often filled with flame-retardant fillers as insulating or sheathing material for wires and cables. Herein, the effects of flame-retardant magnesium hydroxide (Mg(OH)2), aluminum hydroxide (Al(OH)3) and of the traditional reinforcing fillers carbon black (CB) and silicon dioxide (SiO2) on the vulcanization kinetics of EVM were investigated. The vulcanization characteristics showed that the scorch time (T 10) of the unfilled EVM (KB), SiO2/EVM, Mg(OH)2/EVM, and Al(OH)3/EVM composites was about 1.75 min. T 10 of the CB/EVM composite was 2.22 min. Compared with KB, the activation energy (E a ) increased by about 15 kJ/mol for CB/EVM composites and by about 5 kJ/mol for SiO2/EVM, Mg(OH)2/EVM and Al(OH)3/EVM composites. The results indicate that CB delays the vulcanization time of EVM rubber, slows down the rate of vulcanization reaction and improves the safety of vulcanization. The addition of SiO2, Mg(OH)2 and Al(OH)3 has little effect on the vulcanization reaction. The mechanical properties show that CB/EVM is more uniformly vulcanized and has the best mechanical properties with a tensile strength of 17.61 MPa and elongation at break of 404.58 %. Mg(OH)2/EVM and Al(OH)3/EVM samples have prominent vulcanization non-uniformity resulting in poor mechanical properties.

Structural, thermal and dielectric behaviour of exfoliated graphite nanoplatelets (xGnP) filled EVA/EOC blend composites

Nano-composites of xGnP filled ethylene vinyl acetate (EVA)/ethylene-octene copolymer (EOC) (80–20) blend with 0, 1, 3, 5, 9, 11 wt % of xGnP were fabricated by solution casting followed by compression moulding. The room temperature X-ray diffraction (XRD) pattern and field emission scanning electron microscope (FESEM) of the investigated samples reflect distribution of exfoliated graphite nanoplatelets (xGnP) in the EVA/EOC matrix. The thermo-physical properties of the composites were determined by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). DSC analysis shows that with increase in xGnP contents, crystallisation temperature increase and act as a nucleating agent. TGA analysis data validates the stability of composites with increase in xGnP wt % in the composites. The dielectric and conducting behaviours of the studied samples were investigated by computer controlled impedance analyser within the frequency range of 100 Hz to 5 MHz. The room temperature relative permittivity (εr) value increases with rise in wt % of xGnP loading and achieved maximum at 9 wt % and then it falls. Similar behaviour also noticed in ac conductivity study. The nature of charge carriers in the composites were investigated by utilising non-destructive impedance spectroscopy technique. The theoretical fitting of experimental data of Nyquist plot reveals all the compounds perform the bulk behaviour. Additionally, ac conductivity study validates Johnsher’s universal power law which confirms motions of the charges are translational one. I ∼ V characteristics of the studied samples were carried out by using Keithly electrometer which confirms that conduction behaviour was non-Ohmic at lower wt % xGnP loading but Ohmic conduction was achieved at higher wt % xGnP loading. From both impedance and I ∼ V study we have also confirmed the increases in conductance with increase in wt % of xGnP loading and shows similar phenomena as observed in dielectric study.

Structural, thermal and dielectric behavior of two-dimensional layered Ti3C2Tx(MXene) filled ethylene–vinyl acetate (EVA) nanocomposites

Two-dimensional layered conductive material (MXene) filled polymer composite structures were prepared by implementing the solution casting technique. The polymer matrix ethylene–vinyl acetate copolymer (EVA) and for the inorganic segment MXene i.e., titanium carbide (Ti3C2) is used. The MXene i.e., Ti3C2Tx was first synthesized from its corresponding MAX phase, i.e., Ti3AlC2 by HF etching method. The different weight percentage (wt%) of 0, 1, 3, 5, 8, 10, 12 of filled Ti3C2Tx-EVA composites are synthesized by varying the amount of Ti3C2Tx by keeping EVA constant. The formation of Ti3C2Tx/EVA composites were confirmed by different characterization technique such as SEM, XRD, Raman, FTIR, TGA analysis. The electrical and dielectric permittivity measurements of the synthesized composites were carried out in the frequency range of 1 kHz–1 MHz. The 8 wt% of Ti3C2Tx filled EVA composite exhibit higher dielectric properties with low dielectric loss among all weight percentages. The high dielectric properties are due to high electrical conductivity, proper dispersion of filler and synergetic interaction between the matrix and filler.

Exfoliated graphite nanoplatelet (xGnP) filled EVA/EOC blends nanocomposites for efficient microwave absorption in the S-band (2–4 GHz)

Inspired by hazardous effects of electromagnetic waves on human health related to increasing exposure to electronic devices in day-to-day life we have developed a low cost, light weight and flexible EMI shielding material based on exfoliated graphite nanoplatelets (xGnP) filled ethylene vinyl acetate (EVA)/Ethylene-octene copolymer (EOC) blend composite by melt mixing method. X-ray diffraction revel that inclusion of xGnP affect the crystallinity of EVA/EOC blend which has also been seconded by differential scanning calorimetry (DSC) analysis. Electromagnetic interference (EMI) shielding effectiveness of the nanocomposites and electromagnetic properties were conducted over microwave frequency range of 1.5–8 GHz. It has been observed that with inclusion of xGnP into EVA/EOC matrix there is significantly improvement of EMI SE values in S- band (2–4 GHz) region and highest total EMI SE value of −67.63 dB at 30 wt% of xGnP loading was achieved mainly due to absorption mechanism. The composite exhibit ac conductivity of 455.8 S/m which is much higher than that of neat EVA/EOC blends. The dc conductivity 5.3 × 10−8 S/m was obtained for 30 wt% xGnP EVA/EOC blend. To our belief, this EVA/EOC/xGnP composite can be utilized as an efficient EMI shielding material in S-band.

Dielectric and thermal behavior of 0.75BiFeO3-0.25BaTiO3 filled ethylene vinyl acetate composites

Bismuth ferrite-Barium Titanate (BFO-BT) filled ethylene-vinyl acetate copolymer (EVA) composites have been processed by solution casting technique followed by compression molding. The effects of BFO-BT on structural, thermal and dielectric behaviour of the composites have been investigated using X-ray diffraction, field emission scanning electron microscopy, thermal analysis (DSC, TGA) and impedance analyser. As analysed by XRD and DSC analysis, with increase in BFO-BT content the crystallinity of EVA matrix decreases. BFO-BT has great effect on higher thermal stability of the composites. EVA/BFO-BT composites exhibit significantly enhanced relative dielectric permittivity (εr = 182) near the percolation limit of about 30 phr BFO-BT loading at 25 °C and 1 kHz frequency. With 30 phr BFO-BT loading, the dielectric loss of the composite shows only an approximately 2-fold increase i.e., from 0.04 to 0.091. The capacitance and resistance of grains is found from the exploratory Nyquist plots with the assistance of an electrical circuit. A cautious examination of the experimental complex impedance plots and model fitted plots is contemplated which fulfilled the precision of the information tentatively. With enhanced dielectric properties and thermal stability, the BFO-BT filled EVA composite system can be used for solar cells and energy saving devices.

A Geometry Effect of Carbon Nanomaterials on Flame Retardancy and Mechanical Properties of Ethylene-Vinyl Acetate/Magnesium Hydroxide Composites.

This study was aimed at investigating the effects of carbon nanomaterials with different geometries on improving the flame retardancy of magnesium hydroxide–filled ethylene-vinyl acetate (EM). The thermal stability and flame retardancy were studied by thermogravimetric analysis (TGA), limiting oxygen index (LOI), UL-94 test, and cone calorimeter test (CCT). The in situ temperature monitoring system and interrupted combustion offered direct evidence to link flame retardancy and composite structure. Results demonstrated that carbon nanomaterials enhanced the thermal stability and fire safety of EM. The geometry of carbon nanomaterials played a key role in synergistic flame retardancy of EM, with the flame-retardant order of carbon nanotube > nanoscale carbon black > graphene. Based on an online temperature monitoring system and interrupted combustion test, one-dimensional carbon nanotube was more inclined to form the network structure synergistically with magnesium hydroxide in ethylene-vinyl acetate, which facilitated the generation of more continuous char structure during combustion. In parallel, the mechanical property was characterized by a tensile test and dynamic mechanical analysis (DMA). The incorporation of carbon nanomaterials presented a limited effect on the mechanical properties of the EM system.

Dielectric relaxation behavior of exfoliated graphite nanoplatelets filled ethylene vinyl acetate copolymer and ethylene propylene diene terpolymer blend

Exfoliated graphite nanoplatelets(xGnP) filled 50:50 blend of ethylene vinyl acetate copolymer(EVA) and ethylene propylene diene terpolymer (EPDM) composites were prepared by solution casting followed by compression moulding method. The microstructure, dielectric characteristics and conducting behaviour were investigated as function of xGnP loading and frequency range of 102 to 5 × 106Hz. Dielectric constant increases with increase in xGnP loading and showed maximum value at 10 phr loading and then decreases with increase in xGnP loading. The enhancement of dielectric constant is due to Maxwell–Wagner–Sillars (MWS) interfacial polarization between the exfoliated graphite nanoplatelets and EVA/EPDM polymer blend interfaces. From Nyquist plot it is observed that with increase in xGnP loading beyond 6 wt% semicircles are obtained which become prominent above 8 wt% loading. AC conductivity values increases with increase in xGnP loading and a percolation threshold of 6 wt% was observed for EVA-EPDM (50:50) blend system which is much lower than the EVA-xGnP as well as EPDM-xGnP systems. The non-linear current–voltage(I–V) characteristics below the percolation threshold is obtained which is due to tunnelling and at higher xGnP loading, a liner I–V characteristic is due to direct contact between the xGnP nanoplatelets.

Mechanical and morphological properties of modified halloysite nanotube filled ethylene-vinyl acetate copolymer nanocomposites

Abstract Halloysite nanotubes (HNTs) were modified by γ-methacryloxypropyltrimethoxysilane (γ-MPS) as it interacts with the aluminol and silanol groups of HNTs present at the edges and surfaces of HNTs. The polymer composites were prepared by means of the solution casting method with ethylene-vinyl acetate (EVA) copolymer having 45% vinyl acetate (VA) content with different weight percent of modified HNTs (m-HNTs). The modification of the HNTs by γ-MPS increases the interfacial and inter-tubular interactions and the degree of dispersion of the HNTs within the EVA matrix which manifest from increase in crosslinking density. The mechanical properties such as tensile strength, tensile modulus and tear strength of nanocomposites were found to increase because of m-HNT. The glass transition temperature (Tg) and the crystalline percentage decreases for EVA/m-HNT nanocomposites were due to the strong interaction between EVA matrix and filler. Also, the EVA/m-HNT nanocomposites exhibited better thermal stability due to the strong inter-tubular interaction.

Effect of multilayered nanostructures on the physico‐mechanical properties of ethylene vinyl acetate‐based hybrid nanocomposites

Exfoliated graphene oxide (GO) and Mg‐Al‐layered double hydroxides (LDHs) nanostructures (LDHs@GO)‐filled ethylene vinyl acetate (EVA)‐based hybrid nanocomposites were prepared by solution reflux technique followed by injection molding. The physico‐mechanical (including morphological, thermal, and mechanical) properties of LDHs@GO‐based‐layered nanostructures and EVA/LDHs@GO (0‐1 wt%)‐based hybrid nanocomposites were analyzed by field emission scanning electron microscopy, Fourier transform infrared spectroscopy, wide and low angle X‐ray diffraction spectroscopy, differential scanning calorimetry, thermogravimetric analysis, and mechanical (tensile and elongation at break) testing. The morphological studies revealed that LDHs sheets were homogeneously inserted in between GO sheets, while LDHs@GO‐based‐layered nanostructures were found to be easily exfoliated in EVA/LDHs@GO hybrid nanocomposites up to 0.7 wt% loading after which agglomeration occurred. The thermal stability of the hybrid nanocomposites was found to be improved at highest LDHs@GO loading of 0.7 wt%. Mechanical properties (tensile strength and elongation at break) of the hybrid nanocomposites were observed to be enhanced by 70 and 80%, respectively, at LDHs@GO loading of 0.7 wt% and highest values of mechanical properties were obtained. Though, the morphological, thermal, and mechanical properties of the composites were improved, the FTIR analysis did not reveal any chemical interaction between EVA and the LDHs@GO‐based‐layered nanostructures. From the overall results, it is obvious that a significant synergism was observed in terms of morphological, thermal, and mechanical properties of EVA/LDHs@GO hybrid nanocomposites with optimum (less than 1 wt%) loading of LDHs@GO‐based‐layered nanostructures. POLYM. COMPOS., 39:3519–3527, 2018. © 2017 Society of Plastics Engineers

Solvent Transport Through Exfoliated Graphite Nanoplatelets (xGnP) Filled Ethylene Vinyl Acetate Copolymer Vulcanizates

Solvent Transport Through Exfoliated Graphite Nanoplatelets (xGnP) Filled Ethylene Vinyl Acetate Copolymer Vulcanizates

Properties and characterization of ([Mengkuang leaf fiber]‐filled ethylene vinyl acetate)/(natural rubber) blend: Effects of blending sequences and mengkuang leaf fiber loading

(Ethylene vinyl acetate [EVA])/(natural rubber [NR])/(Mengkuang leaf fiber) (MLF) thermoplastic elastomer composites were prepared by using three different blending sequences in an internal mixer. The blending sequences studied were (i) B1: NR was added followed by MLF into the molten EVA; (ii) B2: MLF was added followed by NR into the molten EVA; (iii) B3: MLF was added followed by EVA into the molten NR. The effect of different blending sequences and fiber loadings from 10 to 40 parts by weight per hundred parts of resin on the torque development, tensile properties, thermal degradation, and morphology of EVA/NR/MLF composites was studied. Of the blending sequences investigated, the B1 system is considered the best method for the preparation of EVA/NR/MLF composites. The B1 system produces composites with lower stabilization torque, higher tensile strength, and better thermal stability compared with other systems. At 40 parts by weight per hundred parts of resin of MLF loading, the tensile strength of the composite prepared by using the B1 system was 15% higher than that of B2 system composites, and 8% higher than that of the B3 system. Scanning electron micrographs of the tensile fracture surfaces indicated this system also had good fiber dispersion in the EVA/NR matrix. An increase in MLF loading resulted in an increase of the values of the stabilization torque and the Young's modulus, but a decrease in values of the tensile strength, the elongation at break, and the thermal stability of the composites. Scanning electron microscopy revealed increased fiber pullout in the composites as the loading increased. J. VINYL ADDIT. TECHNOL., 24:109–115, 2018. © 2016 Society of Plastics Engineers

Molecular transport behaviour of organic solvents through halloysite nanotubes filled ethylene–vinyl acetate copolymer

The transport behaviour of three organic solvents (benzene, toluene and xylene) through halloysite nanotubes (HNTs) filled ethylene–vinyl acetate (EVA) copolymer composites have been investigated in the temperature range 303–323 K. The effects of HNTs loading, nature of solvent and temperature on the transport behaviour of solvents through composites were studied. It has been observed that all the systems follow a Fickian mode of transport on increasing temperature. The solvent uptake and sorption coefficient decreases with the increase in halloysite loading while diffusion coefficients and permeation coefficients were found to be dependent on the concentration of filler. The percentage of bounds rubber content and swelling ratio decreases up to 7.5 phr filler content, whereas above 7.5 phr filler loading were found to be increased due to poor dispersion of halloysite in EVA copolymer matrix. The transport behaviour of three organic solvents was further validated by their crosslink density values. The thermodynamic parameters such as enthalpy, entropy and free energy of sorption were evaluated. The positive values of free energy indicate the non-spontaneity of the sorption of HNTs filled EVA in aromatic solvents at 303 K.

Effect of electron beam irradiation on (waste tire dust)-filled ethylene vinyl acetate in the presence of bisphenol a diglycidyl ether

The effect of bisphenol A diglycidyl ether (BADGE) and electron beam (EB) irradiation on the properties of waste tire dust (WTD) -filled ethylene vinyl acetate (EVA) has been studied. The EVA/WTD ratio was fixed to 80:20, whereas the BADGE concentration varied from 1 to 5 wt%. The samples were then irradiated using a 3.0-MeV EB machine at 50 kGy to 200 kGy at increments of 50 kGy. All the samples were subjected to various mechanical, physical, and thermal tests. Prior to irradiation, the mechanical properties of the composites show a gradual decrease with increasing BADGE concentration. Such observation is attributed to the plasticizing effect of the BADGE, as indicated by the reduction in mixing torque and a 14% increase in the elongation at break with the addition of 5 wt% BADGE. Results of gel fraction indicated that BADGE did not accelerate the irradiation-induced crosslinking of EVA/WTD composites. The scanning electron micrographs and tan d curves of EVA/WTD composites showed evidence that the addition of BADGE and EB irradiation of the EVA/WTD improves the compatibility of the composite. The overall results revealed that the irradiated EVA/WTD composite without BADGE gives a better enhancement in mechanical properties compared with the composites incorporated with the BADGE. J. VINYL ADDIT. TECHNOL., 00:000–000, 2015. V C 2015 Society of Plastics Engineers

The effects of a polyol on the damping properties of EVM/PLA blends

Silica filled ethylene-vinyl acetate rubber (EVM) and poly lactic acid (PLA) blends were used as the matrix. DMA was used to investigate the effects of a polyol on the damping properties of the blends. The damping mechanism was investigated by DSC and variable temperature infrared spectroscopy. The results showed that the super branched polyol played the role of a compatibilizer in EVM/PLA blends and it had better affinity with PLA. The polyol greatly improved the damping properties of the EVM/PLA blends due to its inherent dynamic mechanical properties as well as via hydrogen bonds with the blend polymers. 10 and 30 parts polyol broadened the effective temperature range from 66.5 °C to 104.8 °C and 183.3 °C, respectively. The variable temperature IR spectra showed the presence of hydrogen bonds between the OH and CO and COC in the EVM/PLA/polyol composite, and a red shift occurred when the hydrogen bonds between COC and OH dissociated.

Effect of Zeolite Modification via Cationic Exchange Method on Mechanical, Thermal, and Morphological Properties of Ethylene Vinyl Acetate/Zeolite Composites

In this research, organozeolite filled ethylene vinyl acetate (EVA) composites were prepared in a melt-mixing process and followed by compression molding using hot press machine according to standard test specimen. Prior to mixing process, zeolite was modified via cationic exchange of alkylammonium ions. The effect of zeolite or organozeolite loading from 5 up to 25 volume percentages on the properties of EVA/zeolite composites was evaluated. A combination of Fourier Transform Infrared Radiation (FTIR) and scanning electron microscopy (SEM) coupled with energy dispersive X-ray (EDX) analysis were done to characterize the resultant organoclay. Tensile test was performed in order to study the mechanical properties of the composites. EVA filled with organozeolite showed better tensile properties compared to EVA filled with unmodified zeolite, which might be an indication of enhanced dispersion of organophilic clay in the composites. Meanwhile, morphological study using SEM revealed the fibrillation effect of organozeolite. Besides, thermal properties of the composites were also characterized by using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results showed that the application of the cation exchange treatment increases both decomposition and melting temperature of EVA/zeolite composites.

Conductive membranes of EVA filled with carbon black and carbon nanotubes for flexible energy-storage devices

A novel class of flexible carbon black and carbon nanotube filled ethylene-vinyl acetate copolymers (ExByCz) were designed and fabricated as substrates for high-performance flexible supercapacitors' electrodes. The electrodes that employed these substrates exhibited good rate capability, high specific capacitance (214.6 F g−1), high specific power density (10 950 W Kg−1) and high energy density (30.4 W h Kg−1).

Volatile out gassing characteristics of highly filled ethylene vinyl acetate binder materials: Gas phase infra-red spectroscopy

Gas phase Infra-red (IR) spectroscopy has been used to investigate volatile out gassing properties of highly filled poly (ethylene-co-vinyl acetate) materials. A Scout-EN™ heated gas cell was interfaced to a vacuum FTIR spectrometer, and the quantification of evolved species was achieved through calibration of the gas cell with certified gas standards. The volatile out gassing properties were monitored as a function of time under vacuum conditions (<1 mbar). Acetic acid, carbon dioxide and water were identified as the major out gassing products through IR absorption peaks at 1797, 2354 and 3853 cm−1, respectively. A comparison of three highly filled poly (ethylene-co-vinyl acetate) resins is reported. In each case, low molecular weight silicone impurities linked to processing operations were identified in the headspace. Successive out gassing runs (pump downs) showed a diminishing equilibrium release level, suggesting a reduction in initial concentration of volatiles within the material. Two different initial phases of species may exist in highly filled materials; ‘weakly-bound’ and relatively ‘tightly bound’ phases of volatile species. The gas phase IR test methodology reported here is a useful analytical tool for investigating out gassing characteristics at the individual and multi-material levels, providing parameter estimates and material sensitivity data for system level ageing models in support of core programmes in materials qualification and life assessment.

Fabrication and characterization of HCl‐treated clinoptilolite filled ethylene vinyl acetate composite films

AbstractAs received and HCl treated Clinoptilolite (C)‐ethylene vinyl acetate (EVA) composites were prepared via the melt‐mixing technique, and extruded through a single‐screw extruder to obtain composite strips with an average thickness of 0.5 mm. The films were then characterized for their morphological, structural, thermal, and mechanical properties. Optical micrographs show that at higher C loading, the particles form large agglomerates, resulting in the formation of voids on the surface of the films. With increasing zeolite loading, the films become brittle, resulting in reduced Young's modulus. Acid treatment of the C tends to affect the crystal structure of the zeolite, resulting in poor tensile properties of the HCl‐treated zeolite‐filled EVA films. Addition of the zeolite also increased the crystallinity of the structure, acting as a nucleating agent in the EVA crystallization. Modeling of the tensile yield data with Pukanszky model indicate that there is poor interfacial adhesion between the polymer matrix and the filler particles. Thermal characterization studies showed that addition of the zeolites retarded the onset degradation temperature of EVA. However, degradation temperatures including Tmax and the final decomposed temperature were increased, suggesting improved thermal stability due to reduced inter‐chain mobility in the composite materials as a result of increased zeolite loading. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Thermal and Mechanical Properties of Zeolite Filled Ethylene Vinyl Acetate Composites

Ethylene vinyl acetate (EVA) composites filled with zeolite (25 vol.%) were prepared using an internal mixer followed by compression molding machine. In order to enhance the thermal properties and fire retardancy of the composites, an intumescent flame retardant consisting of ammonium polyphosphate (APP)/pentaerythritol (PER) was incorporated into the composites. Two kinds of flame retardants were used which are untreated APP (APP1) and silane treated APP (APP2), where their effectiveness was evaluated by means of differential scanning calorimetry (DSC) and also thermogravimetric analysis (TGA). The results showed that both types of flame retardants have the ability to enhance the thermal stability of EVA/zeolite composites by producing charred layer which protects the underlying composites from the action of flame. Moreover, the incorporation of APP1 and APP2 has a significant effect on the composites degree of crystallinity. Meanwhile the results of tensile testing showed that the composites with APP2/PER exhibit better tensile properties compared to that with APP1/PER. This is expected since the application of silane-treated APP (APP2) could improve the dispersion of APP particles within EVA matrix.

Diffusion and solubility of mineral oils through ethylene-vinyl acetate copolymer

This paper reports a study of mineral oil diffusion through a filled ethylene-vinyl acetate crosslinked polymer, together with some comparisons with aliphatic linear hydrocarbons. Permeation was monitored by classical gravimetric measurements leading to values of solubility and diffusion coefficient at several temperatures ranging from 20 to 120 °C. Diffusion coefficients display a change in activation energy at at ca. 70 °C for mineral oils but not for simple hydrocarbons. The values obtained were discussed regarding available structure-diffusivity relationships and diffusion models derived from free volume theory. A relationship between penetrant evaporation temperature and its diffusivity was observed and tentatively justified.