Ethylene vinyl acetate/Mg‐Al LDH nanocomposites by solution blending

Partially exfoliated ethylene vinyl acetate (EVA‐40, 40% vinyl acetate content)/layered double hydroxide (LDH) nanocomposites using organically modified layered double hydroxide (DS‐LDH) have been synthesized by solution intercalation method. X‐ray diffraction (XRD) and transmission electron microscopy (TEM) studies of nanocomposites shows the formation of exfoliated LDH nanolayers in EVA‐40 matrix at lower DS‐LDH contents and partially intercalated/exfoliated EVA‐40/MgAl LDH nanocomposites at higher DS‐LDH contents. These EVA‐40/MgAl LDH nanocomposites demonstrate a significant improvement in tensile strength and elongation at break for 3 wt% of DS‐LDH filler loading compare to neat EVA‐40 matrix. Thermogravimetric analysis also shows that the thermal stability of the nanocomposites increases with DS‐LDH content in EVA‐40. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Ethylene vinyl acetate/ethylene propylene diene terpolymer‐blend‐layered double hydroxide nanocomposites

Ethylene vinyl acetate (EVA‐45)/ethylene propylene diene terpolymer (EPDM) blend‐layered double hydroxide (LDH) nanocomposites have been prepared by solution blending of 1:1 weight ratio of EVA and EPDM with varying amounts of organo LDH (DS‐LDH). X‐ray diffraction and transmission electron microscopy analysis suggest the formation of partially exfoliated EVA/EPDM/DS‐LDH nanocomposites. Measurement of mechanical properties of the nanocomposites (3 wt% DS‐LDH content) show that the improvement in tensile strength and elongation at break are 35 and 12% higher than neat EVA/EPDM blends. Dynamic mechanical thermal analysis also shows that the storage modulus of the nanocomposites at glass transition temperature is higher compared to the pure blend. Such improvements in mechanical properties have been correlated in terms of fracture behavior of the nanocomposites using scanning electron microscopy analysis. Thermal stability of the prepared nanocomposites is substantially higher compared to neat EVA/EPDM blend, confirming the formation of high‐performance polymer nanocomposites. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

Rubber/LDH nanocomposites by solution blending

The rubber nanocomposites containing ethylene vinyl acetate (EVA) having 60 wt % of vinyl acetate content and organomodified layered double hydroxide (DS‐LDH) as nanofiller have been prepared by solution intercalation method and characterized. The XRD and TEM analysis demonstrate the formation of completely exfoliated EVA/DS‐LDH nanocomposites for 1 wt % filler loading followed by partially exfoliated structure for 5–8 wt % of DS‐LDH content. EVA/DS‐LDH nanocomposites show improved mechanical properties such as tensile strength (TS) and elongation at break (EB) in comparison with neat EVA. The maximum value of TS (5.1 MPa) is noted for 3 wt % of DS‐LDH content with respect to TS value of pure EVA (2.6 MPa). The data from thermogravimetric analysis show the improvement in thermal stability of the nanocomposites by ≈15°C with respect to neat EVA. Limiting oxygen index measurements show that the nanocomposites act as good flame retardant materials. Swelling property analysis shows improved solvent resistance behavior of the nanocomposites (1, 3, and 5 wt % DS‐LDH content) compared with neat EVA‐60. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and characterization of ethylene vinyl acetate/Mg–Al layered double hydroxide nanocomposites

Mg–Al layered double hydroxide (LDH)/Ethylene vinyl acetate (EVA‐28) nanocomposites were prepared through solution intercalation method using organically modified layered double hydroxide (DS‐LDH). DS‐LDH was made by the intercalation of sodium dodecyl sulfate (SDS) ion. The structure of DS‐LDH and its nanocomposites with EVA‐28 was determined by X‐ray diffraction (XRD) and transmission electron microscope (TEM) analysis. XRD analysis shows that the original peak of DS‐LDH shifted to lower 2θ range and supports the formation of intercalated nanocomposites while, TEM micrograph shows the presence of partially exfoliated LDH nanolayers in addition to orderly stacked LDH crystallites in the polymer matrix. The presence of LDH in the nanocomposites has been confirmed by Fourier transform infrared (FTIR) analysis. The mechanical properties show significant improvement for the nanocomposite with respect to neat EVA‐28. Thermogravimetric (TGA) analysis shows that thermal stability of the nanocomposites is higher than that of EVA‐28. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1845–1851, 2007     

Ethylene vinyl acetate copolymer/halloysite nanotubes nanocomposites with enhanced mechanical and thermal properties

Ethylene vinyl acetate (EVA) nanocomposites filled with halloysite nanotubes (HNTs) were prepared by melt compounding. The homogenous dispersion of HNTs into the EVA matrix was evaluated by SEM and TEM analysis. The addition of HNTs does not influence on the phase separation structure and crystallinity of EVA nanocomposites. Due to the reinforcing effect of HNTs embedded in the EVA elastomer matrix, along with an increase of HNTs concentration, the improvement in tensile properties, by means of modulus at an elongation of 100% and tensile strength, was observed. It was found that tensile strength increased by 27% for EVA nanocomposite with 8 wt% of the HNTs. The values of elongation at break at low HNTs' loading increase and subsequently at higher loading are comparable to the neat EVA copolymer. The elastic deformability and reversibility of the EVA nanocomposites with different HNTs content was analyzed. The cyclic tensile tests showed that prepared nanocomposites have values of permanent set slightly higher than for neat EVA copolymer. Furthermore, the limiting oxygen index value for the EVA based nanocomposite with the highest HNTs content (8 wt%) increased from 19.5 to 24.8%. The results show, that thermo-oxidative stability were improved by the incorporation of HNTs into EVA copolymer matrix.     

Effect of layered silicate on EPDM/EVA blend nanocomposite: Dynamic mechanical,thermal, and swelling properties

Polymer blend nanocomposites have been developed by solution method using ethylene propylene diene terpolymer (EPDM), ethylene vinyl acetate (EVA‐45) copolymer, and organically modified layered silicate. Morphological investigation made by wide‐angle X‐ray diffraction and transmission electron microscopic analysis indicates intercalated structure of EPDM/EVA nanocomposites with partial disorder. Scanning electron microscopic studies exhibit the phase behavior of EPDM/EVA blend nanocomposites. Dynamic mechanical thermal analysis shows a significant increase in storage modulus in the rubbery plateau. The decrease in damping (tan δ) value and enhanced glass‐transition temperature (T_g) demonstrate the reinforcing effect of layered silicate in the EPDM/EVA blend matrix. The tensile modulus of these nanocomposites also showed a significant improvement with the filler content. The main chain scission of EPDM/EVA blend nanocomposites compared with the neat EPDM/EVA blend showed substantial improvement in thermal stability in nitrogen, whereas a sizeable increase is observed in air. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Rubber–clay nanocomposite by solution blending

Ethylene vinyl acetate rubber (45% vinyl acetate content, EVA‐45) and organomodified clay (12Me‐MMT) composites were prepared by solution blending of the rubber and the clay. A combination of X‐ray diffraction, scanning electron microscopy, and transmission electron microscopy studies showed that the composites obtained are on the nanometer scale. The measurements of the dynamic mechanical properties for different compositions over a temperature range (?100 to +100°C) showed that the storage moduli of these rubber–clay nanocomposites are higher above the glass to rubber transition temperature compared to the neat rubber. The tensile strength of the nanocomposites is about 1.6 times higher than that of the EVA‐45. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2216–2220, 2003     

New generation layered nanocomposites derived from ethylene‐co‐vinyl acetate and naturally occurring graphite

New ethylene‐co‐vinyl acetate (EVA, with 60% vinyl acetate content) based nanocomposites were prepared with graphites modified by various techniques and a commercially available expanded graphite (EG). The infrared spectra and the surface energy measurements indicated better oxidation and higher surface energy of the graphite modified by mixed acids followed by high temperature treatment (GO). Interlayer space and surface area were increased as a result. EG possessed higher surface area. GO was found to distribute in finer tactoids of average thickness of 25 nm in the matrix, as compared with the unmodified graphite (UG), having average tactoid thickness more than 40 nm along with aggregation. EG also showed finer dispersion in the EVA matrix with some network formation. The dynamic mechanical and the mechanical properties were superior at the 2 wt % concentration of the GO, beyond which the improvement was less, possibly because of aggregation of GO. Greater EVA‐GO interaction at 2 wt % concentration was also supported from the swelling analysis, thermal conductivity, and the thermo‐oxidative degradation data of the hybrid composites. The melt viscosity was lower at 2 wt % GO concentration. EG based nanocomposites registered similar properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation and characterization of ethylene vinyl acetate copolymer/montmorillonite nanocomposite

Ethylene vinyl acetate copolymer (EVA) and monmorillonite (MMT) nanocomposites have been investigated as a function of vinyl acetate content and molecular weight of EVA and types of substituted alkyl ammonium of MMT. It is found that vinyl acetate content and type of substituted alkyl ammonium are important factors for the intercalation behaviour of MMT in MMT/EVA nanocomposite. Maleic anhydride grafted high‐density polyethylene was used as a compatibilizer to improve the intercalation behaviour of MMT. X‐ray diffraction and transmission electron microscopy were used to characterize the intercalation/exfoliation behaviour, and mechanical properties were measured. © 2003 Society of Chemical Industry     

Preparation and characterization of ethylene‐vinyl acetate nanocomposites: enhanced flame retardant

Ethylene‐vinyl acetate (EVA) nanocomposites with enhanced flame retardance were prepared by the sol–gel process in the melt. Two EVAs with different vinyl acetate (VA) contents and aluminium isopropoxide were used as organic and inorganic phases. The nanocomposites were prepared in a batch mixer under constant processing conditions and were analysed by several characterization techniques. Aluminium isopropoxide presented low activation energy, which allows the synthesis of the nanoparticles without a post step treatment. The reaction mechanism is proposed. Nanocomposites with smaller and well dispersed metal nanoparticles were produced with an EVA with higher VA content. EVA nanocomposites achieve the requirements for 94 V‐0 classification. © 2013 Society of Chemical Industry     

Pre‐dispersing of montmorillonite nanofiller: Impact on morphology and performance of melt compounded ethyl vinyl acetate nanocomposites

Ethyl vinyl acetate (EVA) copolymers are potential materials for biomedical applications due to their exceptional mechanical properties and biocompatibility. As new medical device designs continue to reduce in size, new materials are required that exhibit improved strength and toughness. In this research, EVA nanocomposites containing synthetic montmorillonite (MMT) are being investigated as new biomedical materials with similar flexibility, biocompatibility, and biostability to neat EVA, but with far superior tensile strength and toughness. We show that the pre‐dispersing of the organo‐MMT prior to melt compounding with the EVA matrix can facilitate nanofiller exfoliation and dispersion in the EVA, thereby enabling significant improvement of EVA nanocomposite performance when high organo‐MMT loading (5 wt %) was added. It was observed that the polarity of pre‐dispersing medium influenced the nanofiller's surfactant organization and distribution, organo‐MMT exfoliation, and dispersion in the EVA, and also interphases of the host copolymer. Consequently, changes in morphology have brought noticeable effects on the mechanical and thermal properties of the EVA. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43204.     

Multiwalled carbon nanotube/montmorillonite hybrid filled ethylene‐co‐vinyl acetate nanocomposites with enhanced mechanical properties,thermal stability,and dielectric response

Homogeneous multiwalled carbon nanotube/montmorillonite hybrid filler (HMM) dispersion was prepared by co‐ultrasonication and was subsequently used to prepare ethylene‐co‐vinyl acetate (EVA) nanocomposites by solution blending method. XRD and TEM analysis of HMM confirm significant interaction between the montmorillonite (MMT) layers and multiwalled carbon nanotubes (MWCNT) in line with previous reports. Analysis of the nanocomposites shows the constituent fillers to be homogeneously dispersed in EVA matrix. Mechanical properties of neat EVA are remarkably improved with HMM content up to 3 wt% followed by reversion. Maximum improvement observed in tensile strength, elongation at break, and toughness are 424%, 109%, and 1122%, respectively. Results show maximum thermal stability at 4 wt% and best dielectric response at 1 wt% HMM content. Exceptional mechanical and dielectric properties of EVA nanocomposites attained may be attributed to homogeneous dispersion of fillers and improved polymer–filler interaction. Comparison shows excellent synergy between MWCNT and MMT towards mechanical reinforcement of EVA. POLYM. ENG. SCI., 58:1155–1165, 2018. © 2017 Society of Plastics Engineers     

Ethylene propylene diene terpolymer/ethylene vinyl acetate/layered silicate ternary nanocomposite by solution method

A new ternary nanocomposite has been developed using ethylene propylene diene terpolymer (EPDM), ethylene vinyl acetate (EVA‐45) copolymer, and organically modified layered silicate (16 Me‐MMT) from sodium montmorillonite (Na⁺‐MMT). Wide angle X‐ray diffraction and transmission electron microscopic analysis confirmed the intercalation of the polymer chains in between the organosilicate layers and the nanoscale distribution of 16 Me‐MMT in polymer matrix, respectively. The measurement of mechanical properties for 2–8 wt% of 16 Me‐MMT loadings showed a significant increase in tensile strength, elongation at break, and modulus at different elongations. Such an improvement in mechanical properties has been correlated based on the fracture behavior of nanocomposite by SEM analysis. Thermal stability of EPDM/EVA/layered silicate ternary nanocomposites also showed substantial improvements compared with the neat EPDM/EVA blend, confirming thereby the formation of a high performance nanocomposite. POLYM. ENG. SCI., 46:437–843, 2006. © 2006 Society of Plastics Engineers     

Enhancement of radiation‐resistant effect in ethylene–vinyl acetate copolymers by the formation of ethylene–vinyl acetate copolymers/clay nanocomposites

Ethylene–vinyl acetate (EVA) copolymers/clay nanocomposites, prepared by using nonreactive organophilic clay and reactive organophilic clay, were characterized by X‐ray diffraction and by high‐resolution transmission electron microscopy. The influence of gamma irradiation on the structure and properties of the pure EVA and EVA/clay nanocomposites was systematically investigated. In the presence of gamma radiation, the clay can effectively restrain the increase of the storage modulus of EVA/clay nanocomposites, which was supported by dynamical mechanical analysis. Gamma irradiation had almost no effect on the thermal properties of EVA/clay nanocomposites by using nonreactive organophilic clay, but it obviously improved the thermal stability of EVA/clay nanocomposites by using reactive organophilic clay. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2532–2538, 2005     

The effect of trimethylol propane tetraacrylate (TMPTA) and organoclay loading on the properties of electron beam irradiated ethylene vinyl acetate (EVA)/natural rubber (SMR L)/organoclay nanocomposites

Ethylene vinyl acetate (EVA)/natural rubber (SMR L)/organoclay nanocomposites were prepared by melt blending technique with 0–10 phr organoclay loading and 3 phr TMPTA. Electron beam initiated crosslinking on these samples was carried out using a 3.0 MeV electron beam machine with doses ranging from 50 to 200 kGy. XRD results proved that dispersion of organoclay in the nanocomposites was slightly improved by irradiation with TMPTA. This was further supported by transmission electron microscopy images, where the nanoscale dispersion of organoclay was more homogenous throughout the irradiated polymer matrix compared to nonirradiated samples. TMPTA also increased the gel fraction yield, tensile properties and thermal stability of the irradiated neat EVA/SMR L and its nanocomposites. TMPTA was found to act as a crosslink initiator, which promotes crosslink bridges via free radical mechanism in EVA/SMR L matrix. SEM observation shows that the fracture behavior of the irradiated neat EVA/SMR L and its nanocomposites with TMPTA is significantly different compared to the fracture behavior of the nonirradiated neat EVA/SMR L. The distinct failure surface structure formed in the irradiated samples with TMPTA explains the overall higher value of tensile properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Thermal and physicomechanical properties of ethylene-vinyl acetate copolymer and layered double hydroxide composites

A series of ethylene-vinyl acetate (EVA) copolymer films have been prepared with different compositions viz. 2, 4, 6, and 8 wt % layered double hydroxide (LDH) nanoparticles by solution intercalation method. These solution-casted EVA/LDH nanocomposite films were dried and characterized by differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. EVA/LDH films were further tested for tensile strength, density, moisture content, solubility resistance, flammability, and electrical properties. The DSC and FTIR analysis indicate strong interactions between the LDH layers and vinyl acetate groups in EVA. Further, EVA nanocomposite films show enhanced tensile strength, limiting oxygen index (LOI), and flammability rating for the addition of LDH without sacrificing the electrical properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Microstructure and thermal properties of ethylene‐(vinyl acetate) copolymer/rectorite nanocomposites

Ethylene‐(vinyl acetate) copolymer (EVA)/rectorite nanocomposites were prepared by direct melt extrusion of EVA and organo‐rectorite. The microstructures and thermal properties of EVA nanocomposites were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), solid‐state nuclear magnetic spectroscopy, positron annihilation spectroscopy, thermal gravimetric analysis (TGA) and dynamic mechanical analysis techniques. XRD pattern and SEM images show that the intercalated structure is formed and rectorite is finely dispersed in EVA matrix. When organoclay content of the hybrid increases to 7.5 wt%, or pristine rectorite was used instead of organoclay, the crystallization behavior of EVA nanocomposite changes greatly and the ratio of the monoclinic to orthorhombic crystal increases significantly. The relative fractional free volume of the nanocomposite decreases with the increasing organo‐rectorite content, and the values of damping factor (tan δ) for all nanocomposites are lower than that of pure EVA. These facts illuminate that intercalated structure restricts the segment motion and mobilization of polymer chain. TGA results of EVA nanocomposites in air indicate that deacylation of EVA is accelerated because of the catalytic effect and the thermal degradation of the main chain is delayed owing to the barrier effect of silicate layers. Copyright © 2005 Society of Chemical Industry     

Dynamic–mechanical properties of modified poly(ethylene‐co‐vinyl acetate)

To study the relationship among relaxation peaks observed in dynamic mechanical experiments and the structure of poly(ethylene‐co‐vinyl acetate) (EVA), EVA copolymers with different substitution in the carbonyl group were synthesized. EVA was hydrolyzed to obtain poly (ethylene‐co‐vinyl alcohol) and was subsequently reacted with formic, hexanoic, and octanoic acids. The copolymers synthesized were characterized by infrared spectroscopy. Analysis of the DMA spectra of the copolymers showed that their relaxation behavior depends on the vinyl acetate concentration. The α‐ and β‐transitions were observed in EVA copolymers with 8 and 18 wt % of functional groups, and the relationship among relaxation process with the structure of polymer was investigated. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1371–1376, 2005     

Influence of screw speed on the mechanical and rheological properties of poly(ethylene‐co‐vinyl acetate)—organomodified montmorillonite nanocomposites

Poly(ethylene‐co‐vinyl acetate) (EVA) and organophilic montmorillonite clay nanocomposites were manufactured in a co‐rotating twin‐screw extruder using screw speeds ranging between 200 and 800 rpm. The morphology and thermal‐mechanical and rheological properties were studied to establish processing–morphology–property relationships. Particularly for samples produced under higher screw speed ranges, X‐ray diffraction and transmission electron microscopy revealed a tendency of increased exfoliated clay. Although the mechanical properties improved by the presence of clay, they were not altered by the screw speed. The rheological behavior in the solid and melt states were evaluated and showed that the storage modulus of neat EVA subjected to higher screw speed undergoes more pronounced decrease in the storage modulus than the nanocomposites, suggesting that the clay minimizes the effect of the screw speed. This minimization effect could be explained in the light of the assessment of relaxation times that showed stronger physical interactions with the nanocomposites in the molten state. POLYM. COMPOS., 36:854–860, 2015. © 2014 Society of Plastics Engineers     

Ethylene vinyl acetate and ethylene vinyl alcohol copolymer for thermal spray coating application

Ethylene vinyl acetate (EVA) copolymer with varying vinyl acetate (VAc) content, viz. 18%, 28% and 40% has been hydrolyzed using alcoholic NaOH solution. Fourier Transform Infrared Spectroscopy (FTIR) analyses of hydrolyzed polymer showed the presence of both OH group and acetate group indicating that the EVA has been partially hydrolyzed. Differential Scanning Calorimeter (DSC) and Thermo Gravimetric Analyzer (TGA) of EVA and hydrolyzed EVA showed large difference in melting and decomposition temperature, respectively. Hydrolyzed EVA showed higher tensile strength and elongation at break compared to corresponding EVA. Blends of different grades of EVA and ethylene vinyl alcohol (EVAl) with low density polyethylene (LDPE) were applied on grit blasted mild steel surface by flame spray technique. FTIR analysis of blends before and after coating showed no degradation during flame spray. Measurement of adhesion strength of these coating showed that adhesion strength increased on hydrolysis of EVA.