Presence Of Ethylene Vinyl Acetate Research Articles

Electromagnetic wave absorption, EMI shielding effectiveness and electrical properties of ethylene – vinyl Acetate (EVA)/ Polyaniline (PAni) blends prepared by in situ polymerization

Flexible, low cost and scalable microwave absorbing materials are very important for application in the telecommunication area and also in stealth technology for military purpose. In the present work, polyaniline doped with dodecylbenzene sulfonic acid (PAni.DBSA) was synthesized in the presence of ethylene vinyl acetate (EVA) copolymer by in situ inverted emulsion polymerization and the corresponding composites were explored as potential electromagnetic wave absorbing materials and electromagnetic interference shielding materials in the X- and Ku-band frequency range. The properties of the composites, such as rheological, electrical and dielectric properties, were investigated as a function of the composite composition. The findings reveal that the microwave absorption of EVA@PAni composites is influenced by the PAni content, with the optimal attenuation achieved by the composite with 33 vol % PAni. This composite displays superior microwave absorbing performance, with a minimum reflection loss of −39 dB (99.99 % attenuation) at 16.65 GHz. This study demonstrates the potential of EVA@PAni composites as microwave-absorbing materials, mainly in the higher frequency range (Ku band) and open new possibilities of developing flexible, low-cost, lightweight and processable materials for applications in both civil and military field.

Characterization of cellulose acetate/low density polyethylene fibre reinforced composite

Three different compatibilizers were used; namely: Fusabond (FSB) which is a maleic anhydride grafted polyethylene, montanic acid (E wax), and used engine oil (UEO) were incorporated into cellulose acetate/low density polyethylene (CA/LDPE) composites at three fiber contents: 5, 15 and 30 phr. Three series of samples consisting of treated composites using coupling agents were prepared, while one group was left untreated as a reference composite. To assess the performance of the composites, different testing techniques were used. These include attenuated total reflectance spectroscopy(FTIR-ATR), thermogravimetric analysis(TGA), differential scanning calorimetry(DSC), tensile test, dynamic mechanical thermal analysis(DMTA), and scanning electron microscopy(SEM). The presence of ethylene vinyl acetate (EVA) in LDPE enhanced the adhesion at the polymer/fiber interface, as reflected by the increase of Young’s modulus by 75, 166, and 245% respectively compared to neat LDPE, an increase of the storage modulus and a reduction of the damping factor value. Incorporating Fusabond was also found to affect slightly the mechanical properties with high fiber contents compared to the composites without the coupling agent by 13%. On the other hand, the use of montanic acid and used engine oil affected the cellulose acetate fibers distribution within the matrix. The UEO enhanced the dispersion but acted as a plasticizer resulting in a slight reduction of the crystallinity. Moreover, the interaction between the LDPE matrix and the CA fibres was indicated by the resulting fracture surface morphology. The results obtained suggest that the CA/LDPE composites would be suitable for packaging or used in automotive applications.

Preliminary Investigation of Microplastic as a Vector for Heavy Metals in Bye-ma Salt Mine, Wukari, Nigeria

This study is aimed at the preliminary investigation of microplastics as carrier of heavy metals pollution in surface sediment. Heavy metals concentration was determined by FAAS while microplastics characterization was analysed by ATR-FTIR spectrophotometer. The results obtained showed high level of lead (Pb) concentrations which ranged from 21.37 - 32.80 mg/kg across the sampling sites while Cd has the least concentration between 0.04 - 0.80 mg/kg. The concentration of Pb and Cd were above the USEPA permissible limit in sediment. The following absorption bands; 2978.19, 1728.28 and 1458.23 cm-1 with the functional groups; C-H stretch, C=O stretch and CH2 bend indicates the presence of Ethylene vinyl acetate (EVA) in site S2 and S4 respectively. Other microplastics found in the sampling sites are Nylon, Nitrile, Polycarbonate and Poly propylene. This indicates that there is identical distribution of the microplastics in the sampling sites. The quantities of microplastics isolated ranged from 8.11 - 8.16 g across the sites. Aquatic organisms fed on these polymeric materials because of their unique appearance. Hence, heavy metals adsorption will lead to higher concentrations on microplastics which could be ingested and lead serious complication in their intestine.

Ability of Sulfate Reducing Bacteria to Utilize Polymer and Rubber Materials

Polymer materials are an integral part of our lives, but their use is a global environmental problem. Despite this, the development of modern approaches to the utilization of used polymer and rubber materials is currently relevant, including the using of anaerobic microbial destruction of polymers by sulfatereducing bacteria. The aim of the work. To study the ability of sulfate-reducing bacteria to utilize rubber and polymer materials such as solid rubber, ethylene vinyl acetate and foamed polyethylene. Methods. Microbiological (cultivation of sulfate-reducing bacteria, method of serial dilutions), biochemical (Lowry method, measurement of enzymatic activity), physical and chemical (gravimetry, iodometry, potentiometry, gas chromatography-mass spectrometry). Results. It was shown that in the presence of the studied materials as the sole sources of carbon, the amount of sulfate-reducing bacteria increased by 2–3 orders compared to the control without adding the materials. On the 90th day of the experiment the destruction coefficients of the studied materials were low and reached KD=0.21–2.88%. In the cultivation medium with the introduced studied materials, the metabolic and enzymatic activity of sulfate-reducing bacteria are changed, in particular, the production of hydrogen sulfide in the presence of ethylene vinyl acetate and foamed polyethylene increased by 0.8–3 times, and rubber – decreased by 1.2–3.5 times. The catalase activity of the studied bacterial cultures was decreased by 1.4–3.4 times compared to the control without adding of materials. During the exposure period with adding the materials, the lipase activity of bacterial cultures decreased and in some cases almost disappeared. The introduction of materials led to increasing of the short-chain fatty acids synthesis by Desulfovibrio desulfuricans DSM642 and D. vulgaris DSM644 strains, while, on the contrary, Desulfovibrio sp. 10 strain showed the decreasing in acid production. The introduction of rubber only in D. vulgaris DSM644 culture leads to the increasing of acetic and propanoic acids synthesis by 59% and 49.5%, respectively, compared to the control without the introduction of the studied materials. The synthesis of acetic acid in the presence of foamed polyethylene and ethylene vinyl acetate in the cultural liquid of sulfate-reducing bacteria increased by 46.2–419.5% and 69.8–92.6%, and propane – by 23.1–46.2% and 71.9–159.0%, respectively. Conclusions. The presence in cultivation media of rubber, foamed polyethylene and ethylene vinyl acetate as a sole carbon sources led to the changes in enzymatic activity (catalase and lipase), the intensification of hydrogen sulfide synthesis by bacteria was observed as well as acetic, propanoic and butanoic acids synthesis increased. This indicates the potential of sulfate-reducing bacteria to utilize the studied materials via acid formation.

Crystallization and mechanical properties of basalt fiber-reinforced polypropylene composites with different elastomers

In this study, composites based on polypropylene (PP), basalt fiber (BF), polypropylene-graft-maleic anhydride (MAPP) and different elastomers were manufactured by extrusion compounding and injection molding. The main focus of this study was to comparatively investigate the effect of three kinds of elastomers (ethylene–propylene–diene monomer (EPDM), polyethylene–octene (POE) and ethylene–vinyl–acetate (EVA)) on non-isothermal crystallization and mechanical properties of the composites with various BF contents. The tensile test results showed that BF had a reinforcing effect on PP resin, and the addition of MAPP further improved the tensile properties by the enhancement of PP/BF interfacial bonding. Among the elastomers, EPDM was more effective in improving the tensile strength and tensile modulus, while POE significantly toughened the impact strength. Micrographs of scanning electron microscope on the impact fracture surfaces indicated a good dispersion by the addition of POE and EPDM, while some agglomerations were observed in the presence of EVA. The non-isothermal crystallization kinetics were investigated based on Avrami and Mo equations at six different cooling rates by using differential scanning calorimetry. Micrographic images of polarized optical microscopy showed that the spherulite size of PP reduced in the presence of EPDM and EVA.

Devulcanization of Natural Rubber in Composites with Distinct Crosslink Densities by Twin-Screw Extruder

In this study, the effects of the devulcanization process realized by an intermeshing co-rotating twin-screw extruder (ICTSE) on three vulcanized Natural Rubber (NR) composites with different crosslink densities (CD) have been investigated. The extrusion parameters were fixed, as well as the initial material granulometry and auxiliary thermoplastic added to the process. After composites vulcanization, they were characterized accordingly their soluble fraction (SF), crosslink density (CD), mechanical properties and thermogravimetry (TGA). The extrusion was performed on the vulcanized elastomers pursuing selectively crosslink rupture and the same characterization previously cited was conducted on the devulcanized material, except the mechanical properties analysis. The extrusion demonstrate effective devulcanization, evidenced in the increasing of soluble fractions, reduction in crosslink density and thermal stability gain. These results are directly affected by preliminary differences on materials structure and presence of ethylene vinyl-acetate (EVA) on extrusion.

Ethylene vinyl acetate as compatibilizer on cure characteristics and mechanical properties of (natural rubber)/(Recycled acrylonitrile‐butadiene rubber) blends

Ethylene vinyl acetate (EVA) has been used as a compatibilizer for (natural rubber)/(recycled acrylonitrile‐butadiene rubber) (NR/NBRr) blends, vulcanized by sulfur. EVA offers excellent heat, ozone, and weather resistance, whereas the vinyl acetate groups provide oil resistance to the blend. It exhibits good tear resistance and may be crosslinked. However, EVA exhibits poor low‐temperature flexibility. NBR gloves have excellent resistance to punctures, tears, and many types of chemicals, while NR has good physical and mechanical properties. NR/NBRr blends were prepared with various compositions with the EVA content fixed. Tensile properties, hardness, and swelling behavior tests were performed to determine the compatibility of NR/NBRr blends in the presence of EVA. Results indicated that incorporation of EVA into NR/NBRr blends improved tensile strength, modulus, and elongation at break compared with NR/NBRr blends without EVA. The improvement in hardness and reduction in resilience on compatibilization are due to an increase in crosslink density, which gives NR/NBRr blends better swelling resistance. Scanning electron microscopy of the fracture surfaces indicates that, with the addition of EVA in NR/NBRr blends, better adhesion between NR and NBRr was obtained, thus improving the compatibility of NR/NBRr blends. J. VINYL ADDIT. TECHNOL., 23:135–141, 2017. © 2015 Society of Plastics Engineers

Plasticized chitosan/polyolefin films produced by extrusion

Plasticized chitosan and polyethylene blends were produced through a single-pass extrusion process. Using a twin-screw extruder, chitosan plasticization was achieved in the presence of an acetic acid solution and glycerol, and directly mixed with metallocene polyethylene, mPE, to produce a masterbatch. Different dilutions of the masterbatch (2, 5 and 10wt% of plasticized chitosan), in the presence of ethylene vinyl acetate, EVA, were subsequently achieved in single screw film extrusion. Very small plasticized chitosan domains (number average diameter <5μm) were visible in the polymeric matrix. The resulting films presented a brown color and increasing haze with chitosan plasticized content. Mechanical properties of the mPE films were affected by the presence of plasticized chitosan, but improvement was observed as a result of some compatibility between mPE and chitosan in the presence of EVA. Finally the incorporation of plasticized chitosan affected mPE water vapor permeability while oxygen permeability remained constant.

The effect of gamma irradiation on mechanical, and thermal properties of recycling polyethylene terephthalate and low density polyethylene (R-PET/LDPE) blend compatibilized by ethylene vinyl acetate (EVA)

A study has been made on the compatibility of recycled polyethylene terephthalate (R-PET) and low density polyethylene (LDPE) blend in the presence of ethylene vinyl acetate (EVA) as a compatibilizing agent prepared by extrusion hot stretching process. EVA content in the blend as a compatibilizing agent was an enhancement effect on radiation crosslinking of R-PET/EVA/LDPE blends and the highest radiation crosslinking was obtained when the EVA content was reached at 10 % EVA when irradiated by gamma irradiation. Blends containing different (EVA) ratios were irradiated to different doses of gamma irradiation 25, 50 and 100 kGy. The effect of the compatibilizer and radiation on mechanical, thermal properties of R-PET together with LDPE and morphology has been investigated. It was found that gamma irradiation together with the presence of compatibilizing agent (EVA) has positive effect on the mechanical and thermal properties of R-PET/LDPE blend. The structural properties of R-PET/LDPE modified by gamma irradiation and EVA as compatibilizing agent was examined by SEM. Also, it was found that the optimum concentration of EVA and gamma irradiation dose was found to be 10 % EVA and 100 kGy, respectively.

A Novel Hydroxyapatite/Ethylene-Vinyl Acetate/Copolymer 66 Composite for Hard Tissue Regeneration

The stiffness and bioactivity of polyamide 66 (PA66) have been previously improved by the addition of hydroxyapatite (HA); however, the toughness and processing ability of the HA/PA66 composite need further improvement. In this paper, ethylene-vinyl acetate (EVA) copolymer was used as a modifier to toughen the composite and improve the melt processability. The HA/EVA/PA66 ternary composites were prepared by a twin screw extruder and injection molding, and analyzed by XRD, DSC, SEM, and mechanical testing. The results demonstrate that EVA has good miscibility with a PA66 matrix and result in a uniform distribution of fine HA particles in the composite. With increasing EVA incorporation, the brittle fracture of PA66 and HA/PA66 gradually became ductile fracture. EVA can effectively improve the impact strength and melt processability of the composite; the increased brittleness of HA/PA66 composite by HA addition can be counteracted by incorporation of EVA modifier. The increase in impact strength of the HA/EVA/PA66 composite can be explained on the basis of better stress transfer in the presence of EVA and by finer dispersion of HA particles.

Morphology and thermal properties of maleic anhydride grafted polypropylene/ethylene–vinyl acetate copolymer/wood powder blend composites

AbstractMaleic anhydride grafted polypropylene (MAPP) was blended with ethylene–vinyl acetate (EVA) copolymer to form MAPP/EVA polymer blends. Wood powder (WP) was mixed into these blends at different weight fractions to form MAPP/EVA/WP blend composites. Differential scanning calorimetry (DSC) analysis of the blends showed small melting peaks between those of EVA and MAPP, which indicated interaction and cocrystallization of fractions of EVA and MAPP. The presence of MAPP influenced the EVA crystallization behavior, whereas the MAPP crystallization was not affected by the presence of EVA. Scanning electron microscopy, Fourier transform infrared spectroscopy, and DSC results show that the WP particles in the MAPP/EVA blend were in contact with both the MAPP and EVA phases and that there seemed to be chemical interaction between the different functional groups. This influenced the crystallization behavior, especially of the MAPP phase. The thermogravimetric analysis results show that the MAPP/EVA blend had two degradation steps. An increase in the WP content in the blend composite led to an increase in the onset of the second degradation step but a decrease in onset of the first degradation step. The presence of WP in the blend led to an increase in the modulus but had almost no influence on the tensile strength of the blend. The dynamic mechanical analysis results confirm the interaction between EVA and MAPP and show that the presence of WP only slightly influenced the dynamic mechanical properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Optimization of polyethylene/binder/polyamide extrusion blow-molded films. III. Slippability improvement with fatty acid amides

The slippability of packaging films has to be controlled to facilitate confectionary operations and guarantee an easy opening for filling. In the case of single-layer polyethylene (PE) films, the addition of slip agents made of fatty acid amides such as erucamide or oleamide usually allows the tailoring of the coefficient of friction (COF) in the film to match industrial targets, which depend on the final application. The coupling of Fourier transform infrared spectroscopy and atomic force microscopy analysis showed that this method has a limited efficiency and may even be detrimental in the case of multilayer PE + ethylene vinyl acetate (EVA)/maleic anhydride grafted polyethylene (PEgMAH) + EVA/polyamide films. The reason is that the migration of the slip additives toward the outermost surface of the PE layer, which leads to a reduction in the COF, are strongly affected by both the existence of the adjacent layers and the presence of EVA in the PE and PEgMAH layers. Nevertheless, a proper knowledge of the effect of this perturbation allows one to reach a slippability level that is required for some confectionary operations and/or for an easy opening for filling without the degradation of the heat sealability. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Influence of ethylene vinyl acetate on the spinnability and mechanical properties of poly(propylene)/zeolite‐Ag blend fibers

AbstractThe spinnability and mechanical properties of poly(propylene) (PP)/zeolite‐supported Ag+ (zeolite‐Ag)/ethylene vinyl acetate (EVA) ternary blend fibers were studied. It was found that the spinning temperature of the ternary blend fibers was decreased in the presence of EVA. The addition of 2 wt % EVA substantially improved the spinnability of the blend system by enhancing its flowability. It was also found that the ternary fiber with EVA28 (28 wt % vinyl acetate content) showed balanced improvement of mechanical properties by a concomitant increase in modulus and tensile strength. The improvements of spinnability and mechanical properties suggested that a core–shell structure of zeolite‐Ag/EVA28 particles, with zeolite‐Ag as the core and EVA28 as the shell, was formed and remained during the melt‐mixing process of the blended chips and during the course of fiber processing. EVA probably enhanced the binding between the zeolite‐Ag and the PP matrix, as made evident in SEM microphotographs. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1460–1466, 2005