Ethylene Vinyl Acetate Matrix Research Articles

Synthesis of stable fluorescent ethylene-vinyl acetate copolymers based on in-situ grafted rare-earth organic complexes and antioxidants through transesterification

The synthesis and application of rare earth organic complexes (REOCs) are gaining attention due to their advantages including low excitation thresholds and high luminescence efficiencies. However, their integration as functional fillers in polymer matrices is constrained by challenges related to poor dispersion and limited stability. This study introduces a novel method for synthesizing stable fluorescent polymers by co-grafting europium (Eu) complexes and the antioxidant 3,9-bis-{1,1-dimethyl-2[β-(3-tert-butyl-4-hydroxy-5-methylphenyl-)propionyloxy]ethyl}-2,4,8,10-tetraoxaspiro[5.5]-undecane (AO-80) onto an ethylene-vinyl acetate (EVA) matrix through an in-situ synchronous grafting strategy, aiming to address these dual challenges of poor dispersion and rapid aging. In this study, Eu complexes characterized by low excitation thresholds and high hexahydrate (EuCl3) and selected ligands - 1,10-phenanthroline (Phen), alpha-thienyl trifluoroacetone (HTTA), and 4-acetoxybenzoic acid (4-ABA). Through transesterifications, the Eu complexes were successfully grafted onto the EVA chain, achieving a uniform dispersion within the EVA matrix to form fluorescent polymers. Furthermore, the incorporation of antioxidant AO-80 as a radical scavenger can significantly mitigate fluorescence attenuation. Through detailed exploration of transesterifications under various conditions, optimal grafting rates of 11.34% for EVA with Eu complexes and 22.87% for EVA with AO-80 were achieved. The synthesized fluorescent polymers of EVA synchronously grafted with Eu complexes and AO-80 have been proven to obtain markedly improved fluorescence stability and aging resistance by outdoor aging tests. Our findings not only validate the in-situ reaction grafting method as an efficient strategy for producing polymer composites with excellent fluorescence stability but also pave the way for future research aimed at overcoming the limitations of REOCs in photovoltaic and agricultural applications.

Removal of encapsulant ethylene-vinyl acetate for recycling of photovoltaic modules: Hansen solubility parameters analysis

Delamination of photovoltaic modules is crucial for the recovery of solar cell materials. In this article, we investigate the swelling of ethylene-vinyl acetate (EVA) using various organic solvents at a temperature range between 25 and 55°C. The swelling of the encapsulant EVA caused by the interaction of organic solvents aids in the separation of glass, solar cell, and Tedlar layer in the recycling of photovoltaic modules. Further, we quantify the interactions between the encapsulant EVA and the organic solvents by the solvent weight ratio and solvent volume ratio of EVA. The quantification of interactions between encapsulant EVA and various organic solvents is used to estimate the Hansen solubility parameters of encapsulant EVA. The temperature-dependent variation of physical properties of organic solvents and their effect on encapsulant EVA swelling are described. Organic solvents retained in encapsulant EVA matrix after drying at room temperature can be viewed as a method to reduce emissions of volatile organic compounds during recycling. Additionally, our experiments suggest that d-limonene, xylene, and toluene are the most effective solvents for delamination of end-of-life photovoltaic modules for recycling.

Acoustical Efficiency and Physico-Mechanical Characteristics Study for New Composite Material: Ethylene Vinyl Acetate and Wood Sawdust

Developing neoteric composite materials (CM) that improve the acoustic efficiency and mechanical properties become the target of many scientists in the last decade. This paper presents research on developing new CMs using Ethylene Vinyl Acetate (EVA) and sawdust (SD) of different weight concentrations which can be help to improve the acoustic and mechanical properties of the EVA polymer materials. Prototypes of EVA composite in form of flat plates with different weight concentrations of sawdust namely; 0, 2.5, 5, 10, 20 and 30% were produced. One of the interesting applications of this new CMs is to use it as a floor covering in buildings and manufactures. The acoustic efficiency parameters namely, impact noise reduction and sound absorption are experimentally studied. The obtained results articulate that covering floors with the designed composite material of EVA/SD as filler can decrease ISR up to 14 dB. Also, it gives peak sound absorption coefficient about 0.6 for 30 % of SD at mid-frequency band. The greatest proportion of SD aggregate EVA does not entail a higher acoustic performance. The tensile strength of the composite increases to 15.5% when the SD content is 5% and the tensile strength drops with increase the SD content up to 30%. Therefore, SD may be utilized as filler and consolidation in the EVA matrix, which will save expenses and assist the environment.

High‐Resolution Printed Ethylene Vinyl Acetate Based Strain Sensor for Impact Sensing

AbstractThe strongly growing interest in digitalizing society requires simple and reliable strain‐sensing concepts. In this work, a highly sensitive stretchable sensor is presented using a straightforward and scalable printing method. The piezoresistive sensor consists of conductive core–shell microspheres embedded in an elastomer. As the elastomer, ethylene vinyl acetate (EVA) is employed as an efficient and cost‐effective alternative compared to polydimethylsiloxane (PDMS). EVA allows for a significantly lower percolation threshold and low hysteresis compared with PDMS. Using 35 µm microspheres, a detection limit of 0.01% is achieved. When using 4 µm microspheres, the sensor shows a detection limit of 0.015% and electromechanical robustness against 1000 cycles of 0–1% strain. The stretchable strain sensor is successfully implemented as an impact sensor and a diaphragm expansion monitoring sensor. Fast (20 ms) and high‐resolution response as well as mechanical robustness to strain values greater than the linear working range of the sensor are demonstrated. The results of this research indicate the promising potential of employing conductive microspheres embedded in the EVA matrix for fast and precise strain detection applications.

A novel strategy for preparing ethylene‐vinyl acetate composites with high effective flame retardant and smoke suppression performance by incorporating piperazine pyrophosphate and Ce‐MOF

AbstractCerium‐containing metal organic framework defined as Ce‐MOF was prepared and then combined with piperazine pyrophosphate (PAPP) for preparing flame retardant ethylene vinyl acetate (EVA) copolymer composites. The samples of EVA/PAPP/Ce‐MOF achieved UL‐94 V‐0 rating with the limiting oxygen index (LOI) value of 31.3% when 17 wt% PAPP/Ce‐MOF with the mass fraction of 97:3 was introduced. Under the same loading amount of PAPP, the EVA/PAPP only obtained UL‐94 V‐1 rating with the LOI value of 26.9%. Cone calorimeter test confirmed that the total heat release and total smoke production of EVA/PAPP/Ce‐MOF significantly reduced from 132.8 MJ m−2 and 11.5 m2 for EVA/PAPP to 98.8 MJ m−2 and 7.3 m2, with a reduction of 25.6% and 36.5%, respectively. Besides, the maximum smoke density decreased from 488.8 and 375.9 for EVA and EVA/PAPP to 177.5 for EVA/PAPP/Ce‐MOF. It indicated that the addition of Ce‐MOF and PAPP effectively exerted synergistic flame retardant and smoke inhibition effect for EVA. Moreover, the addition of Ce‐MOF enhanced the compatibility of PAPP with EVA matrix, and water resistance of EVA/PAPP/Ce‐MOF was higher than that of EVA/PAPP. The x‐ray photoelectron spectroscopy texts of residual char of EVA composites indicated that the cerium ion complexed with phosphoric acid and polyphosphate generated by the thermal decomposition of PAPP and then more phosphorus elements remained in condensed phase. As a result, the sufficient, crosslinking and dense char layer with excellent intensity was formed, and the heat, combustible gas and smoke were efficiently inhibited. Consequently, the EVA materials were endowed excellent fire safety as well as low heat and smoke release.

Dual modification of EVA by long chain phosphaphenanthrene grafted MXene and black phosphorene nanosheets for simultaneously enhanced thermal stability and flame retardancy

It is significant to develop high-efficient fire retardants all the time. Ethylene vinyl acetate (EVA) features flammability and poor fire resistance ability, which severely hindered its extensive application with advanced requirements. Herein, a novel strategy was proposed to combining long chain phosphaphenanthrene grafted MXene (DPP-MXene, also donated as DM) and black phosphorene nanosheets (BP) with EVA to fabricate EVA/DMBP nanocomposites with high fire resistance. Thermogravimetric analysis (TGA) proved that DMBP synergistic system can significantly improve the thermal stability and char forming ability of EVA as proved by delayed thermal decomposition temperatures. The combustion test results suggested that the addition of 3 wt. % DMBP into EVA matrix can induce the EVA/DMBP-3 composites with favorable flame resistance property, the UL-94 V-0 rating and limiting oxygen index (LOI) value (26.7 %) was achieved for the EVA/DMBP-3 components, and significantly decrease in total heat release (THR) (21.5 %) and peak heat release rate (PHRR) (48.1 %) were achieved by addition of 3 wt. % DMBP into EVA elastomer, indicated its incombustible nature. Furthermore, it was found that the incorporation of DMBP synergistic system only yielded the EVA/DMBP-3 composites with slight reduction of the tensile strength and elongation at break as compared to neat EVA. The high efficiency of the prospect flame retardant provided a competitive candidate material for EVA towards wide applications.

Влияние содержания технического углерода на вольт-амперные характеристики полимерных композитов

The influence of the concentration (C) of technical carbon (CB) on the current-voltage characteristics (CVC) of composites based on an ethylene vinyl acetate matrix has been studied. It has been established that in polymer composites with low (С = 5%) and high (С  25%) concentrations, the conductivity is practically independent of the electric field strength. In composites with CB concentrations corresponding to the percolation region, the presence of two pronounced segments of the CVC was found. After reaching a certain threshold field, a sharp increase in conductivity was observed. The behavior of the current-voltage characteristics of such composites in the region of high fields is described with good accuracy by the Fowler-Nordheim expression.

Towards Circular Economy by the Valorization of Different Waste Subproducts through Their Incorporation in Composite Materials: Ground Tire Rubber and Chicken Feathers.

Incorporation of residua into polymeric composites can be a successful approach to creating materials suitable for specific applications promoting a circular economy approach. Elastomeric (Ground Tire Rubber or GTR) and biogenic (chicken feathers or CFs) wastes were used to prepare polymeric composites in order to evaluate the tensile, acoustic and structural differences between both reinforcements. High-density polyethylene (HDPE), polypropylene (PP) and ethylene vinyl acetate (EVA) polymeric matrices were used. EVA matrix defines better compatibility with both reinforcement materials (GTR and CFs) than polyolefin matrices (HDPE and PP) as it has been corroborated by Fourier transform infrared spectroscopy (FTIR), termogravimetric analysis (TGA) and scanning electron microscopy (SEM). In addition, composites reinforced with GTR showed better acoustic properties than composites reinforced with CFs, due to the morphology of the reinforcing particles.

A biobased flame retardant towards improvement of flame retardancy and mechanical property of ethylene vinyl acetate

A new biobased flame retardant (MHPA) with remarkable compatibility was synthesized via a facile and low-cost neutralization reaction of magnesium hydroxide (MH) and phytic acid (PA). By blending the prepared MHPA into ethylene vinyl acetate (EVA), the fire retardancy, smoke suppression and mechanical properties of the composites were significantly improved. When 50 wt% of MH was added into EVA matrix, the value of limiting oxygen index (LOI) reached 26.1%. Whereas, when 10 wt% MH in the EVA composites (with initial 50 wt% MH) was replaced by MHPA, the resulted EVA composites had a LOI value of 30.8%, indicating high efficiency of addition of MHPA to improve flame retardancy. Moreover, the heat release rate (HRR) and total smoke production (TSP) of the EVA composites reduced by 54.4% and 27.6%, respectively, suggesting that incorporation of MHPA could effectively hinder rapid degradation of EVA composites during burning process. The fire-retardant mechanism may reside in that the MHPA combined with MH can present the excellent carbonization and expansion effects. This study illustrates that the biobased MHPA has a broad application prospect to develop flame-retardant EVA composites.

Preparation of high‐efficient ethylene‐vinyl acetate‐based thermal management materials by reducing interfacial thermal resistance with the assistance of polydopamine

AbstractThe rapid development of electronic technology puts forward higher requirements for thermal management materials. In this paper, polydopamine (PDA) was employed to improve the interfacial interaction between filler and matrix, and then to further regulate the interfacial thermal resistance and thermal conductivity of ethylene‐vinyl acetate (EVA) composites. It was found that boron nitride (BN) sheets and carbon nanotubes (CNTs) can fully exert the synergistic heat conduction effect with the assistance of PDA, and construct continuous and efficient heat conduction channels in EVA matrix. When 30 vol% BN and 2 vol% CNTs were added, the in‐plane thermal conductivity of the composite reached 9.61 W·m−1·K−1, which was about 3225% higher than that of EVA matrix. The contribution of PDA to auxiliary enhanced thermal conductivity was further verified by the fitting and calculation of the interfacial thermal resistance of the composites. In addition, the EVA composite material had sensitive thermal response and stable electrical insulation properties, which ensured its thermal management applications in electronic equipment.

Improving thermal conductivity of ethylene-vinyl acetate composites by covalent bond-connected carbon nanotubes@boron nitride hybrids

Efficient thermal management materials have become one of the main challenges faced by the rapid development of current electronic technology. In this study, a covalent bond was first designed to connect carbon nanotubes (CNTs) and boron nitride (BN) to prepare CNTs@BN hybrids, and then the prepared CNTs@BN hybrids were used to enhance the thermal conductivity of ethylene-vinyl acetate (EVA) matrix. The results indicated that the covalent bond connections between CNTs and BN effectively reduced the interfacial thermal resistance and promoted the construction of a continuous and efficient heat conduction network. Finally, the thermal conductivity of EVA composite reached 7.84 W m−1 K−1, which was 2613% higher than that of EVA matrix. The sensitive response of EVA composite to temperature further demonstrated its excellent thermal management capability. The EVA composite also had good thermal stability and stable electrical insulation performance, which further guaranteed its application in electronic equipment.

Influence of encapsulation materials on the thermal performance of concentrator photovoltaic cells

The Ethylene-Vinyl Acetate (EVA) layer in the polycrystalline solar cells suffers from lower thermal conductivity. Therefore, this work presents a numerical study for a possible way to enhance the thermal conductivity of the lower encapsulant layer. A comprehensive three-dimensional (3D) model is proposed to evaluate the conventional and modified solar cell performance. The ongoing research study can be achieved by doping three different nanoparticles of Boron Nitride (BN), Zinc Oxide (ZnO), and Silicon Carbide (SiC) with loading ratios of 10%, 20%, and 30% to the lower EVA matrix layer. The present numerical work was conducted under 20 suns concentration ratio and variable coolant flowrates. The findings reveal that a significant reduction in local and average solar cell temperature is achieved for all studied cases, especially at a 30% loading ratio of n-SiC. Moreover, it is observed that the net gained electrical power was enhanced by 7.16% at the same SiC loading ratio. However, ZnO and BN fillers reported a slight percentage increase of 6.77% and 5.95%, respectively. The thermal and electrical efficiency has been improved with the new EVA-nanoparticle layer due to lower average cell temperature. Therefore, at 1200 ml/h, the thermal and electrical efficiency achieved the highest value in SiC than BN and ZnO; the maximum value was reported 70.02% for thermal efficiency and 16.94% for electrical one.

Ethylene vinyl acetate copolymer/Mg–Al‐layered double hydroxide nanocomposite membranes applied in CO2/N2 gas separation

AbstractSeries of ethylene vinyl acetate (EVA) copolymer/layered double hydroxide (LDH) nanocomposite membranes with 40 wt% vinyl acetate content (EVA/12AA–LDH) were prepared by solution blending and casting, and applied in membrane gas separation. The organically modification of LDH nanolayers (12AA–LDH) was manufactured by using 12‐aminododecanoic acid (12AA) as an intercalation agent via co‐precipitation method. The distance between the 12AA–LDH nanolayers was approximately 2.10 nm from calculation of the XRD diffraction pattern, which resulted from the successful intercalation of 12AA within the LDH. The result of CO2 adsorption isotherms shows that 12AA–LDH is much more attractive than the neat LDH, which enhances the performance in membrane separation. Furthermore, the exfoliated/intercalated morphology of 12AA–LDH/LDH structures within EVA matrix was prepared successfully and can be observed clearly by transmission electron microscopy micrographs. The gas permeation performance of the EVA/12AA–LDH nanocomposite membranes was measured, and the results show that the best selectivity of CO2/N2 increased to 20 with a CO2 permeability of 119.21 barrer for the composite membrane containing 1.0 wt% 12AA–LDH. This result not only attributed to the exfoliation of the 12AA–LDH nanolayers within the EVA matrix, but also the amino group of 12AA interacted more with CO2 compared with N2 and O2. This result illustrated that 12AA–LDH shows highly potential for use as an additive in CO2 capture membranes.

Gas-permeation properties of sandwich-like polyaniline/poly(ethylene vinyl acetate) nanocomposite membranes

The effect of the use of sandwich-like polyaniline (S-PANI) nanocomposites in CO2 gas-separation membranes was investigated. S-PANI nanocomposites were synthesized via a two-step dispersion polymerization method. The first step was to manufacture a leaf-like polyaniline (L-PANI), which was used in the next step as a 2D template to synthesize the S-PANI. SEM images show that a three-layer sandwich-like structure of the S-PANI was successfully synthesized. ATR-FTIR measurements revealed that the S-PANI has a structure with conductive PANI layers on both sides of the L-PANI template. Furthermore, the N2 and CO2 adsorption isotherms illustrate that S-PANI is much more attractive to CO2 than N2 because of the amine functional groups of S-PANI. Hence, the CO2/N2 separation performance of the ethylene vinyl acetate (EVA) copolymer membrane was successfully enhanced by the addition of the S-PANI nanocomposite. The CO2/N2 selectivity of the membrane increased from 6.8 to 32.5 with a 3-wt% loading of S-PANI within the EVA matrix. The results show that 2D S-PANI could feasibly be used for CO2 gas membrane separation.

The Role of Zinc Chloride in Enhancing Mechanical, Thermal and Electrical Performance of Ethylene Vinyl Acetate/Carbonized Wood Fiber Conductive Composite.

Carbonized natural filler can offer the production of low cost composites with an eco-friendliness value. The evolving field of electronics encourages the exploration of more functions and potential for carbonized natural filler, such as by modifying its surface chemistry. In this work, we have performed surface modification on carbonized wood fiber (CWF) prior to it being used as filler in the ethylene vinyl acetate (EVA) composite system. Zinc chloride (ZnCl2) with various contents (2 to 8 wt%) was used to surface modify the CWF and the effects of ZnCl2 composition on the surface morphology and chemistry of the CWF filler were investigated. Furthermore, the absorptive, mechanical, thermal, and electrical properties of the EVA composites containing CWF-ZnCl2 were also analyzed. SEM images indicated changes in the morphology of the CWF while FTIR analysis proved the presence of ZnCl2 functional groups in the CWF. EVA composites incorporating the CWF-ZnCl2 showed superior mechanical, thermal and electrical properties compared to the ones containing the CWF. The optimum content of ZnCl2 was found to be 6 wt%. Surface modification raised the electrical conductivity of the EVA/CWF composite through the development of conductive deposits in the porous structure of the CWF as a channel for ionic and electronic transfer between the CWF and EVA matrix.

Simultaneously improving mechanical strength, hydrophobic property and flame retardancy of ethylene vinyl acetate copolymer/intumescent flame retardant/FeOOH by introducing modified fumed silica

Series of flame-retardant ethylene vinyl acetate (EVA) composites with excellent properties were prepared by adjusting the fraction of fumed silica (FS). The surface morphologies, mechanical property, hydrophobicity, thermal property and the related flame-retardant properties were measured and investigated in details. The scanning electron microscopy (SEM) and mechanical property results showed that the certain addition of FS could effectively improve the interface compatibility between EVA matrix and flame retardant (FR). Moreover, the tensile strength and elongation at break were increased to 20 MPa and 675.0 %, respectively. High hydrophobicity of the EVA composite could also be achieved proved by high contact angle (85°) and low water absorption (0.2 %), respectively. In addition, cone calorimeter test (CCT) results indicated the value of heat rate release of EVA composites decreased by 63.6 % with the addition of FS compared to pure EVA due to the formation of char layer by protecting char residue and insulating fire and heat transmission, which was confirmed by SEM and thermogravimetric analysis (TGA) analysis. Besides, the anti-dripping effect of FS was indicated by limiting oxygen index (LOI) and UL-94.

Fabrication of surface-modified magnesium hydroxide using Ni2+ chelation method and layer-by-layer assembly strategy: Improving the flame retardancy and smoke suppression properties of ethylene-vinyl acetate

A novel magnesium hydroxide-polyphosphazene-Ni2+ (MH-PZPN-Ni) was synthesized by the layer-by-layer assembly strategy and Ni2+ chelation method. Post modification, the composite was incorporated into ethylene-vinyl acetate (EVA). The morphology, composition and structure of the MH-PZPN-Ni composites were comprehensively characterized by scanning electron microscopy, transmission electron microscope, Fourier transform infrared, X-ray diffraction and X-ray photoelectron spectroscopy. MH-PZPN-Ni could efficiently increase the flame retardancy and smoke suppression of EVA. The MH-PZPN-Ni (60 wt %)-incorporated EVA composite showed a limiting oxygen index value of 30.4 % and was rated as a UL 94 V-0 material. Cone calorimeter test results showed that the peak heat release rate and total heat release of EVA/MH-PZPN-Ni were decreased by 85.8 % and 56.7 %, respectively when compared to pure EVA. The morphology, structure, and chemical composition of the char residue and the pyrolysis products formed during the decomposition of the EVA composites were analyzed to investigate the flame-retardant mechanism of the modified EVA matrix. The production of ammonia (during the process of PZPN-Ni decay) and the water vapor formed due to the combustion of the H· and OH· radicals were found to dilute the concentration of the generated combustible gases. The denser char layer effectively blocked the heat and mass transfer. At the same time, the use of the Ni catalyst resulted in a significantly low production of various volatile products (such as CO and aliphatic and aromatic compounds). Moreover, PZPN-Ni enhanced the mechanical properties of EVA. The elongation at break increased by 74.9 %.

Influence of silicon dioxide addition and processing methods on structure, thermal stability and flame retardancy of EVA/NR blend nanocomposite foams

Rubber nanocomposite foams based on 60/40 ethylene vinyl acetate (EVA)/natural rubber (NR) were melt-mixed with flame retardant silicon dioxide (SiO2) (20 parts per hundred rubber, phr), and foamed by compression molding process. In this study, the effect of mixing phenomena of SiO2 through two different compounding techniques such as direct mixing (DM) and phase selective mixing (PSM) methods on structure, thermal stability, combustility and flame retardancy of EVA/NR blend nanocomposite foams were investigated. DM method is a melt mixing of EVA, NR, layered silicate and SiO2, followed by foaming. PSM is a new method based on pre-mixing EVA with SiO2, then melt mixing of EVA/SiO2 masterbatch with NR and layered silicate, and finally foaming. Based on TEM technique, it was found that the SiO2 was exclusively located in dispersed NR phase for the sample prepared by DM method, and the SiO2 was preferably dispersed in continuous EVA matrix when PSM method was employed. However, the different mixing methods did not significantly alter their cellular structures. The thermal stability and char residue content of foamed samples with SiO2 increased obviously when compared with those of corresponding foams without SiO2. The results based on limiting oxygen index (LOI) test and oxygen bomb calorimetry indicated that the foams combined with SiO2 had better combustion resistance and flame retardancy due to barrier effect of thermally stable silicon-based char layer. Further, the SiO2 filled foamed system obtained from the PSM method showed a higher degree of improvement in thermal stability, combustion resistance and flame retardancy than that of DM method because the homogeneous dispersion of SiO2 in EVA matrix rather than the selective dispersion in NR phase. This resulted in the continuity of flame retardant EVA/SiO2 phase in the 60/40 EVA/NR nanocomposite foams, which exerted more efficient fire barrier of the silicon-based char layer.

Comparing Multi-Walled Carbon Nanotubes and Halloysite Nanotubes as Reinforcements in EVA Nanocomposites.

The influence of carbon multi-walled nanotubes (MWCNTs) and halloysite nanotubes (HNTs) on the physical, thermal, mechanical, and electrical properties of EVA (ethylene vinyl acetate) copolymer was investigated. EVA-based nanocomposites containing MWCNTs or HNTs, as well as hybrid nanocomposites containing both nanofillers were prepared by melt blending. Scanning electron microcopy (SEM) images revealed the presence of good dispersion of both kinds of nanotubes throughout the EVA matrix. The incorporation of nanotubes into the EVA copolymer matrix did not significantly affect the crystallization behavior of the polymer. The tensile strength of EVA-based nanocomposites increased along with the increasing CNTs (carbon nanotubes) content (increased up to approximately 40% at the loading of 8 wt.%). In turn, HNTs increased to a great extent the strain at break. Mechanical cyclic tensile tests demonstrated that nanocomposites with hybrid reinforcement exhibit interesting strengthening behavior. The synergistic effect of hybrid nanofillers on the modulus at 100% and 200% elongation was visible. Moreover, along with the increase of MWCNTs content in EVA/CNTs nanocomposites, an enhancement in electrical conductivity was observed.

Ethylene vinyl acetate (EVA)/poly(lactic acid) (PLA) blends and their foams

Thermoplastic elastomer from ethylene vinyl acetate (EVA) was blended with a biodegradable polymer, poly(lactic acid) (PLA), to develop ecofriendly EVA/PLA foams. The thermal and mechanical properties and the morphologies of the blends with various PLA contents between 0 and 40% were investigated. The rheological properties during gel formation were monitored via in-situ through the evolution of torque with curing time. The EVA/PLA blends showed a two-phase morphology made of a continuous EVA matrix and micron or submicron nodules, and also increased the tensile strength and modulus, as well as hardness, with the increase of the added PLA content. This should be attributed to the micronic dispersion of the rigid PLA in the elastic EVA matrix. The foam samples containing below 30% of PLA exhibited a similar cell structure and foaming ratio to the pure EVA; however, the cell size and foaming ratio gradually reduced with the increase of the added PLA content.