Ethylene Vinyl Acetate Content Research Articles

Achieving Efficient Intrinsically Stretchable Organic Photovoltaics with a Conjugated and Elastomeric Dual‐Network Morphology

AbstractStretchable organic photovoltaics (OPVs) are pivotal for advancing conformable electronics, yet achieving both efficient and intrinsically stretchable OPVs remains a significant challenge. The main issue is maintaining electronic and mechanical properties under deformation. Here, a ternary blend system, PTzBI‐oF:PYIT:EVA is presented, incorporating ethylene‐vinyl acetate (EVA) to establish a conjugated and elastomeric dual‐network morphology. The elastomer network dissipates applied stress, preserving the crystalline packing of the conjugated network and enabling improved mechanical stability of charge carrier generation and transport. Specifically, with 15% EVA content, the ternary blend achieved a power conversion efficiency (PCE) of 15.28% in rigid devices and exhibited a crack onset strain of 17.23%. Notably, the stretchable OPVs retained over 80% of their initial PCE under 30% strain. These findings underscore the potential of conjugated and elastomeric dual‐network morphology in developing high‐performance stretchable electronics for various applications.

Enhancement of porous asphalt mixtures modified with various fibers and ethylene–vinyl acetate polymer

Porous asphalt mixture is conventional hot mix asphalt (HMA) with substantially decreased fines, which produces an open-graded mixture that enables the water to flow through an interconnected void space. Porous asphalt is a permeable system that has a lot of benefits. However, because of its open structure, the durability of this mixture decreases, and both its stability and resilient modulus are much lower compared to the dense conventional asphalt mixtures. Also, the high void percentage may lead to an increase in the draindown proportion. Fibers (cellulose or mineral) and polymer-modified binders are recommended for porous asphalt mixtures, especially in hot and moderate climates. The objective of this study is to improve the porous asphalt mixture's performance by using ethylene–vinyl acetate (EVA) polymer-modified bitumen. Two types of fibers (cellulose fibers and glass wool fibers) were used, separately to determine the control mixture. Four different proportions of EVA polymer were added to the bitumen (1%, 2%, 3%, and 4%) and Scanning Electron Microscopy (SEM) was used for better investigating of the bitumen microstructure, then The Marshall mix design was used to determine the optimum EVA content (OEC) for the porous asphalt mixture. Several performance tests were conducted to investigate the characteristics of the porous asphalt mixture, such as the infiltration rate, binder draindown, the wheel track and the cantabro abrasion tests. The findings of the study conclude that the addition of EVA polymer to the porous asphalt mixtures enhances the performance as it increases stability by 20.8% and the infiltration rate by 20.6%. It decreases binder draindown proportion by 33.3%, cantabro abrasion loss by 25.1% and the rut depth at 5,000 cycles and 10,000 cycles by 29.8% and 19.7%, respectively.

Experimental Evaluation of Mechanical Properties, Thermal Analysis, Morphology, Printability, and Shape Memory Performance of the Novel 3D Printed PETG‐EVA Blends

AbstractPolyethylene terephthalate glycol (PETG) is a novel amorphous shape memory polymer with excellent printability for 4D printing. In this article, ethylene‐vinyl acetate (EVA) is used as a biocompatible and non‐toxic copolymer to improve plasticity and shape memory performance of PETG. PETG‐EVA blends are prepared and 3D printed using a melt mixing method and an upgraded fused deposition modeling (FDM) with a pneumatic feeding system. The results of the thermal analysis show that the blends exhibit two tan‐delta peaks, each related to their components, and morphology images confirm that they are biphasic and immiscible with good compatibility. The morphology of both EVA10 and EVA30 matrix droplets is observed, with the droplets being larger for EVA30. The use of a pneumatic feeding system, along with the ability to control the output melt flow, results in the best printing ability for EVA30, with minimal microholes between the grids and interlayer cracks. The tensile strength of PETG‐EVA blends ranged from 25.38 to 20.14 MPa, with the highest tensile strength achieved for EVA30. The shape memory performance of all three blends is similar; with shape recovery exceeding 90% in 20 s. Blends with higher EVA content exhibited faster shape recovery within the first 10 s.

Improved processability for ultra‐high molecular weight polyethylene/polyolefin elastomer composites: Effect of ethylenevinyl acetate copolymer

AbstractPolyolefin elastomer (POE) films can be used as a matrix for ultra‐high molecular weight polyethylene (UHMWPE) fiber‐reinforced composites via a hot‐melt process. However, the low melting temperature of UHMWPE limits composite processing. Therefore, this study aimed to create a film by blending POE with ethylene vinyl acetate (EVA) to reduce the film's processing temperature. Morphological analysis revealed that due to limited compatibility, EVA appeared as droplets within the immiscible POE matrix. T‐Peel tests demonstrated increased self‐adhesion in both the POE/EVA films and the fiber‐reinforced composites with higher EVA content. However, the mechanical properties of POE/EVA films, including tensile properties and shore hardness, were reduced due to EVA having lower inherent properties. UHMWPE fiber‐reinforced composites were fabricated from these films. In composites, optimal tensile and flexural properties were observed at lower EVA content. Scanning electron microscopy analysis suggests that the POE/EVA films are sufficiently infiltrated at 10–20 wt% EVA content. As EVA content increased, the drop weight impact test indicated a reduction in the maximum impact load and an increase in impact energy, attributed to improved adhesion and a broader distribution of impact load across the interface.Highlights Polyolefin elastomer/ultra‐high molecular weight polyethylene composites' properties were studied with varying ethylene vinyl acetate (EVA) additive content. Add EVA to improve film impregnation when forming composites Increase in impregnation affects increase in properties of composites. Characterization shows that the optimal EVA content is 10–20 wt%.

Effect of Ethylene-Vinyl Acetate on the properties of Polybutylene Terephthalate/ Ethylene-Vinyl Acetate polymer blends

This research study analyzes the influence of Ethylene-Vinyl Acetate (EVA) resin on the properties of Polybutylene Terephthalate (PBT)/EVA blends produced by injection molding technique. It is based on the fact that a way to recycle PBT from toothbrush bristles is needed. Mechanical samples were made by mixing EVA into PBT with 0, 5, 10, 15, 20, and 25% contents. The samples were tested for flexural strength, impact strength, and hardness according to the standards of ASTM D790, ASTM D256, and ASTM D2240, respectively. The results show that when increasing the EVA content in the PBT/EVA blends, the flexural strength tends to decrease; the hardness fluctuates along a decreasing trend; however, the decrease is not significant. Interestingly, the measured impact resistance results are very positive, especially at the highest increase point, increasing by 40.7% compared to neat PBT. The microstructure results showed a good dispersion of EVA on the PBT substrate, but there was no compatibility between these two polymers. The results of XRD analysis showed that when EVA was mixed, it increased the crystallinity and improved the crystal growth of the blends.

Utilization of Ethylene-Vinyl Acetate (EVA) Waste from Footwear Industry as Partial Replacement of Aggregates for Concrete Roof Tile

Scraps of Ethylene-Vinyl Acetate (EVA) foams from cutting out shoe soles are a waste produced by the footwear industry, and the recycling of these thermosetting materials is quite expensive and requires distinct procedures. Hence, an upcycling route to turn such waste into valuable material, such as utilizing it as a partial aggregate replacement in the production of concrete roof tile, was explored. This paper aims to investigate the effects of EVA on the bulk density, water absorption, thermal properties, water permeability, and transverse breaking strength of the concrete roof tile. The weight percentages of replaced natural aggregates in the concrete roof tile mixture are 5%, 7.5%, and 10%. The concrete roof tile with EVA aggregates demonstrated a lighter weight but higher water absorption. Also, its thermal conductivity presents promising results as it lessens the heat transfer compared to conventional concrete roof tiles. Moreover, the incorporation of EVA also positively affects the concrete roof tile's water permeability as it can hold the water longer than those without EVA. Finally, the transverse breaking strength of the concrete roof tiles with EVA contents resulted little or no difference compared to the conventional concrete roof tile.

Polymer blend particles with dual-phase morphology prepared using a novel one-pot method via a phase inversion emulsion procedure

We develop a new method for preparing polymer blend particles with dual-phase morphology based on a phase inversion emulsion process. Using this method, the polystyrene (PS)/ethylene–vinyl acetate (EVA) copolymer particles were prepared and analyzed. The preparation procedure included a emulsification of liquid styrene monomer with dissolved EVA and a following free radical polymerization to convert the monomer droplets into solid blend particles.The obtained PS/EVA particles had a dual-phase morphology. With increasing EVA content, the structure of EVA dispersed in PS matrix switched from spherical, stripe to nearly co-continuous morphology and the particles become significantly tougher and the maximum impact strength reached 9.13 KJ/m2. This method provides the opportunity to prepare a number of new kinds of polymer blend particles with tailored performance even though the composed polymers are condensation polymers or unreachable at atmospheric pressure.

Effect of Hydrophilic Polyurethane on Interfacial Shear Strength of Pisha Sandstone Consolidation under Freeze-Thaw Cycles.

The W-OH type polyurethane (W-OH) has been proven to be an economical and environmentally friendly slope protection solution for slope maintenance in Pisha sandstone areas. However, the Pisha area belongs to a typical temperate continental climate with large diurnal temperature changes in winter, spring, and autumn and freezing and thawing occurring alternately between days and nights. Under freeze-thaw cycle conditions, the effect of slope treatment largely depends on the interface shear strength between W-OH-treated Pisha sandstone and pristine sandstone. Therefore, this paper studies the interfacial shear strength and long-term durability of Bisha sandstone consolidation (W-OH-treated Pisha sandstone) and Pisha sandstone under freeze-thaw cycles. First, the effects of different W-OH concentrations and different water contents on the freeze-thaw cycle interface were studied using a direct shear test. Based on the experimental results, the W-OH material was further modified with ethylene vinyl acetate (EVA). Finally, the damaged surface of the sample was observed through an ultra-depth-of-field microscope, and the damage mechanism of the interface caused by the freeze-thaw cycles was further discussed. The experimental results show that the peak shear strength at the interface increases with the increase in W-OH concentration and decreases with the increase in freeze-thaw cycles. The cohesion at the interface generally increases with the increase in W-OH concentration and reaches a maximum value of 43.6 kPa when the W-OH concentration is 10%. At the same time, under the condition of high water content, the curing of the W-OH material has no significant effect on the bonding performance of the interface. Using EVA to modify the W-OH material can improve the freeze-thaw durability of the interface. After modification, the interfacial cohesion of the sample increases with the increase in the EVA concentration and can reach 162% of the original. Using an ultra-depth-of-field microscope, it was found that the repeated solidification-melting action of water between the interfaces makes the consolidated body on the damaged surface fall off, resulting in cracks. As the water content between the interfaces increases, the damage to the material is greater. However, the addition of EVA can fill the uncovered pores of W-OH cement, thereby improving the cohesion at the interface and effectively alleviating the freeze-thaw damage caused by the high water content at the interface. The results of this study can provide some theoretical references for slope treatment in the Pisha sandstone area using W-OH materials.

Optimize PLA/EVA Polymers Blend Compositional Coating for Next Generation Biodegradable Drug-Eluting Stents.

In this research work, polymer blends of poly-lactic acid (PLA)/ethylene vinyl acetate (EVA) were prepared as the drug carrier materials for a bi-layer drug-loaded coating film for coronary stents. Different optimum compositions of blends were prepared by using an intense mixer. Then, the blends were hot-pressed and later cold-pressed to prepare for films of different thickness. The changes in weight, surface analysis and biodegradability with increasing time were studied using Scanning electron microscopy (SEM), weight loss and biodegradability tests. The mechanical and thermal properties of drug-loaded films were studied through universal testing machine (UTM) and thermo-gravimetric analysis (TGA). The effects of PLA, EVA and drug contents on in-vitro drug contents were investigated through the Ultraviolet-Visible Spectroscopy (UV-VIS) chemical analysis technique. The results obtained clearly showed that the addition of PLA promoted the unleashing of the drug whereas the addition of EVA nearly did not have the same affect. The mechanical properties of these various films can be tuned by adjusting the contents of blend parts. The factors affecting the unleashing of the drug became a serious matter of concern in evaluating the performance of bio-resorbable drug eluting stents. As a result, today’s chemical blends may be useful drug carrier materials for drug-loaded tube coatings capable delivering purgative drug in an incredibly tunable and regulated manner.

Effects of temperature and humidity on properties of ethylene/vinyl acetate‐modified ternary complex mortar

AbstractThe ternary complex system of Portland cement, aluminate cement, gypsum is suitable for the repair and strengthening of concrete structures due to its excellent characteristics, such as fast hardening, early strength, micro‐expansion, and so on. However, the application of this ternary complex was limited by the problems of low toughness and strength degradation in the late curing period. Therefore, it is meaningful to study the effects of different curing conditions on repairing materials in concrete engineering. In this paper, the actual repair environment was simulated, and the effects of different curing temperature and humidity on performances of ethylene/vinyl acetate (EVA) modified ternary complex were researched. The initial and final setting time of ternary complex increases with the increase of EVA content. And under different curing temperature and humidity, the addition of EVA improved the toughness of the ternary complex and reduced the water absorption, EVA can effectively prevent the late strength decrease of ternary complex caused by high curing temperature. Under the curing conditions of 40 and 60°C, the addition of EVA greatly improved the flexural strength and toughness of the ternary complex, low temperature environment is not suitable for EVA‐modified ternary complex.

Effect of EVA copolymer containing different VA content on the thermal and rheological properties of bio-based high-density polyethylene/ethylene vinyl acetate blends

The effect of ethylene vinyl acetate (EVA) concentration and vinyl acetate (VA) content of EVA on the mechanical, morphological, and rheological properties of bio-based high-density polyethylene (BioPE)/EVA blends was investigated. The blends were characterized by X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, and rheological measurements under oscillatory shear flow. The degree of crystallinity of BioPE decreased with the increase in the EVA concentration and was unaffected with the increase in the VA content. DMTA results showed a decrease in the storage modulus (E′) with the increase in EVA content and that the BioPE/EVA19 blends showed higher E′ values than BioPE/EVA28 blend. The impact strength substantially increased with the addition of EVA concentration above 5 mass% and was higher for the blends containing the highest VA content. The blends containing a higher content of VA exhibited the higher EVA dispersed phase domain size, which increased with the increase in EVA concentration. The complex viscosity increased with the increase in the EVA content, being higher for the BioPE/EVA blends containing higher VA content. The storage modulus increased, at low frequencies, with the increase in the EVA content and can be ascribed to the increase in the EVA dispersed phase domain size.

Effect of ethylene-vinyl acetate (EVA) on stone mastic asphalt (SMA) behaviour

Stone Mastic asphalt (SMA) has been of interest in research in pavement engineering. Different climates and load conditions sometimes dictate to use special products such as SMA. Due to traffic load and new developments, sometimes it is vital to develop new mixes with higher capabilities to withstand the loads. This study investigates the effect of Ethylene-Vinyl Acetate (EVA) on SMA fatigue and rutting behaviour. By application of wet techniques, EVA was blended with C320 binder and SMA mixes were prepared. EVA dosage was varied from 2% to 6%. A four-point flexural beam test, wheel rutting test, Schellenberg test, flow number test and dynamic modulus test were conducted on the mixes. The outcomes saw clear improvements in rutting resistance and the cycle to failure in four point bending test, was improved with increases in the percentage of EVA. The flow number also increased by increasing the EVA concentration. The drainage of bitumen was decreased by increasing the EVA concentration. Finally, the master curve relevant to each EVA concentration was plotted and compared. Phase angle of mixes also decreased by increasing the EVA percentage.

Study On Rheological Properties Of Eva Modified Asphalt Based On Fractional Derivative Theory

Based on the fractional derivative theory, the relation between fractional derivative operator and power function empirical creep equation has been established. And the physical meaning of the power function parameters has been clarified. Ethylene-vinyl acetate (EVA) has been used as additives to prepare modified asphalt with content of EVA modifier varying from 0% to 9% in increments of 3% by weight of asphalt. Dynamic frequency sweep tests have been conducted on EVA modified asphalt using dynamic shear rheometer at 30°C, 40°C, 50°C, and 60°C. The complex shear modulus and the rutting factor of the asphalt modified by EVA increase with the increase of EVA content and decrease with the increase of temperature. The results indicate that the EVA modified asphalt reduced thermal sensitivity and increased resistance to permanent at high temperatures. Also, the power function parameters of EVA modified asphalt have been studied and analysed based on fractional derivative theory.

Weathering characteristics of wood-plastic composites compatibilized with ethylene vinyl acetate

Poplar wood flour wood-plastic composites (WPCs) prepared with high-density polyethylene and modified with different amounts of ethylene vinyl acetate (EVA) were created. The influence of EVA content on the surface properties and weathering characteristics after ultraviolet (UV) treatment was investigated. The results showed that WPCs treated with EVA had improved thermal stability, and the surface polarity was reduced. The addition of EVA slowed the fading of the WPCs, and the color difference was the smallest when the EVA content was 5%. Both the bending strength and the modulus of elasticity (MOE) of the WPCs decreased after the UV treatment. However, when the EVA content was 5%, the bending strength retention ratio and MOE retention ratio were greatest. Scanning electron microscopy showed that the addition of EVA reduced the amount of pores and gaps on the fractured surfaces of the WPCs. The comprehensive performance of the WPC anti-weathering properties was greatest when the EVA level was 5%.

Characteristics of compound asphalt modified by waste tire rubber (WTR) and ethylene vinyl acetate (EVA): Conventional, rheological, and microstructural properties

Waste tire rubber (WTR) and waste plastic ethylene vinyl acetate (EVA) has been widely used as modifier for the improvement of asphalt individually. However, there are little studies applied the combination of WTR and EVA to the modification of asphalt to enhance its performance. This study aims to study the modifying effect of the combination of WTR and EVA on the asphalt. The conventional test and the rheological test, which including penetration test, softening point test, viscosity test, and dynamic shear rheological test were exerted to appraise the physical properties. Meanwhile, the force-ductility test and the Bending Beam Rheology test were exerted to evaluate the low-temperature performance of modified asphalt. Furthermore, the temperature and frequency sweeps were employed by using dynamic shear rheometer (DSR) to simulate the loading and temperature conditions in asphalt-based pavement mixtures. Finally, microscopy features were studied by the FTIR and environment scanning electronic microscopy (ESEM). The preliminary results of this study showed that the combination of WTR and EVA improved the high-temperature properties of the asphalt, which were manifested in reducing penetration, increasing softening point and viscosity in the laboratory. The temperature sweep results illustrated that temperature dominantly influence the elastic component at the temperature range from 30 °C to 90 °C. By combining with the rutting factor of asphalt, the fitting data of zero shear viscosity (ZSV) at 60 °C showed that with the increase of WTR or EVA content (by wt.), the resistance to rutting deformation was greatly ameliorated. FTIR results and ESEM photography identify that both WTR and EVA have perfectly mingled with asphalt. Lastly, it is concluded from the performance comparisons of the modified asphalts with different combined WTR and EVA, the optimal combination of this series of samples on high-temperature properties was 15%WTR +4%EVA.

Performance Evaluation of the Polyurethane-Based Composites Prepared with Recycled Polymer Concrete Aggregate.

Currently the investigation on recycled cement concrete aggregate has been widely conducted, while the understanding of the recycled polymer concrete aggregate is still limited. This study aims to fill this knowledge gap through the experimental investigation on mechanical and durability performance. Specifically, the remolded polyurethane stabilized Pisha sandstone was collected as the recycled polymer concrete aggregate. The remolded Pisha sandstone was then applied to re-prepare the polyurethane-based composites. After that, the mechanical performance of the prepared composites was first examined with unconfined and triaxial compressive tests. The results indicated that the Pisha sandstone reduces the composite’s compressive strength. The reduction is caused by the remained polyurethane material on the surface of the remolded aggregate, which reduces its bond strength with the new polyurethane material. Aiming at this issue, this study applied the ethylene-vinyl acetate (EVA) to enhance the bond performance between the polyurethane and remolded sandstone. The test results indicated both the unconfined and triaxle compressive strength of the polyurethane composites were enhanced with the added EVA content. Furthermore, the durability performance of the EVA-modified composites were examined through freeze-thaw and wet-dry cycle tests. The test results indicated the EVA could enhance the polyurethane composites’ resistance to both wet-dry and freeze-thaw cycles. Overall, the modification with EVA can compensate for the strength loss of polyurethane composites because of the applied remolded aggregate and enhance its sustainability.

Preparation and properties of ethylene-vinyl acetate copolymer-based blend foams

In this study, ethylene-vinyl acetate (EVA) copolymer-based blend foams with polyolefin elastomers (POEs), low-density polyethylene, or styrenic thermoplastic elastomers were prepared as a potential resilient material for reducing inter-floor noise. Various properties of EVA blend foams were measured in order to reveal the effects of EVA content and types of pair polymers consisting of EVA blend foams on dynamic stiffness, which is one of the key factors of resilient materials, in relation to hardness, specific gravity, and resilience. These properties had not been introduced by the construction industry until now. When the EVA/POE ratio was 20/80 and the foaming ratio was 210%, dynamic stiffness presented the lowest value at 5.97 MN m− 3. However, when the resilience was <20%, dynamic stiffness was as high as 37.66 MN m− 3 at an expansion ratio of 210% even when the specific gravity was low.

Experimental and numerical simulation of phase change process for paraffin/expanded graphite/ethylene-vinyl acetate ternary composite

A series of paraffin/expanded graphite (EG)/ethylene–vinyl acetate (EVA) ternary composites were prepared. An experimental test system and a simulation model of paraffin/EG/EVA composites were built. According to the temperature change and the distribution of the temperature in the experiment, solid-liquid phase change of composites were simulated. Based on the results, the thermal behavior during the phase change of the composites was analyzed, and the influence of EG and EVA on the phase change process was discussed. The results showed that the leakage rate of the composites was about 3% with the EVA content changed. EG significantly accelerated the phase change of the composites. Samples with high EG content cost 50% less time to phase change than samples with low EG content. It was supposed that the effect of the high thermal conductivity of EG was stronger than viscosity.

Compressive and Flexural Strengths of EVA-Modified Mortars for 3D Additive Construction.

The compressive and flexural strengths of mortars modified with ethylene-vinyl acetate (EVA) were experimentally investigated for use in three-dimensional (3D) additive construction (3DAC). EVA powder, which is available in a premix type, was employed as an admixture. The test results for the cast specimens showed that, at a curing age of 28 days, the compressive strengths ranged from 32.92 MPa to 43.50 MPa, and the flexural strengths ranged from 12.73 MPa to 14.49 MPa. The compressive and flexural strengths of the printed specimens were relatively lower: 23% to 26% and 3% to 7%, respectively. The compressive strength also decreased and the flexural strength increased when the EVA/cement ratio was increased. The results of the experiment reveal that the EVA-modified mortar had a high rate of strength development early on, making the material advantageous for use in 3DAC. It was determined that the appropriate EVA/cement ratio ranged between 5% and 15%. However, the printed specimens exhibited lower compressive and flexural strengths than did the cast specimens, and the compressive strength decreased as the EVA content was increased. This study provides the compressive and flexural strengths of common EVA-modified mortars, important data for 3DAC applications.

Rheology, Mechanical Properties and Morphology of Poly(lactic acid)/Ethylene Vinyl Acetate Blends

In this work, the effect of ethylene vinyl acetate (EVA) content on the rheology, mechanical properties, and morphology of poly (lactic acid) (PLA)/EVA blends was investigated. Differential Scanning Calorimetry (DSC) showed that the addition of EVA to PLA decreased the degree of crystallinity of PLA. Dynamic Mechanical Thermal Analysis (DMTA) results showed that the presence of EVA copolymer increased the cold crystallization temperature (Tcc) of PLA. The addition of 10% of EVA to PLA substantially increased the impact strength. Morphology analysis by Scanning Electron Microscopy (SEM) indicated the immiscibility between PLA and EVA phases and an in increase the EVA average dispersed phase domains size with the increase in EVA content. Rheological measurements under oscillatory shear flow showed that storage modulus (G′) increased with the increase in the EVA content at low frequencies and is related to the increase in the EVA dispersed phase domains size, as also observed by relaxation spectrum analysis. Cole–Cole plots of imaginary viscosity (η″) versus real viscosity (η′) and Han plots of storage modulus (G′) versus loss modulus (G″) indicated that PLA and EVA phases are immiscible, as also observed by SEM.