Ethylene Vinyl Acetate Copolymer Research Articles

Rheological Tunable Solid–Liquid Two‐Phased Binary Metals Enable Thermoplastic and Electronic Conductive Composites for Conductive Adhesives and Conductive Wires

AbstractThermoplastic conductive composites are significant materials in modern electronic technologies due to their universal fabrication conditions, phenomenal electrical conductivity, and remarkable mechanical properties. However, due to the heavy phase separation occurs during thermo‐processing between conductive inorganic fillers and polymer matrixes. Conventional thermoplastic conductive composites exhibit low electrical conductivity, and undesirable mechanical properties, which significantly restrict their applications. This work successfully arrives at the solution for the phase segregation by combining gallium‐stannum binary metal (Ga/Sn BM) and commercial ethylene vinyl acetate (EVA) copolymer to successfully realize thermoplastic conductive composites. The thermoplastic conductive Ga/Sn BM‐EVA composites which exhibit remarkable thermal processability, ultrahigh electrical conductivity, and considerable mechanical performance. Rheological tunable solid‐liquid two‐phased Ga/Sn BM with tunable viscosities is the key to achieve excellent miscibility between fillers and polymers. The rheological measurement results demonstrate the critical viscosity matching between Ga/Sn BM and EVA copolymer for the successful fabrication of thermoplastic conductive composites. More importantly, the Ga/Sn BM‐EVA composites are adapted with classic polymer melt‐processing, which indicates the scalable production. The thermoplastic conductive Ga/Sn BM‐EVA composites emerge as an exciting substitute for electronic conductive hot melt adhesives and conductive wires in intelligent electronic technologies.

Multiscale experimental and simulation analysis on the synergistic modification mechanism of nano-SiO₂/EVA at the recycled concrete interface

ABSTRACT To enhance the reuse of construction waste in structural materials and improve the interfacial transition zone (ITZ) in recycled concrete (RC), this study employed two modification strategies and conducted a multiscale analysis to compare the effects of combined Nano-SiO2 (NS)/ethylene-vinyl acetate copolymer (EVA) modification and EVA-only modification on the mechanical properties, hydration characteristics, and microstructure of RC. The aim was to better overcome the interface defects in recycled concrete through synergistic modification. Experimental results show that the incorporation of EVA and NS significantly improves the mechanical properties of RC, with the combined modification outperforming the single modification. Specifically, when EVA content is 5% and NS is 2%, the 28-day compressive, shear, and flexural strengths of concrete increased by 15.7%, 17.6%, and 18.5%, respectively. Microscopic tests, including scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR), revealed that the cement matrix became denser, the porosity decreased, and the content of hydrated calcium silicate (C-S-H) increased. Molecular dynamics (MD) simulations indicate that EVA-only modification enhances interfacial bonding through hydrogen and ionic bonds, while the combined modification further strengthens the interface by forming additional Si-O-Si bonds, thereby improving the overall cohesion between the new and old concrete.

Influence of modifying additives on the structure and properties of biodegradable mixtures based on poly-3-hydroxybutyrate and nitrile butadiene rubber

Objectives. To investigate polymer composite materials based on poly-3-hydroxybutyrate (PHB) of microbiological origin and the synthetic nitrile butadiene rubber NBR-28. The biodegradability of PHB implies the possibility of its use for invasive medical purposes; however, this is significantly limited by its brittleness. The aim of this work was to search for approaches to altering the molecular structure of PHB-based composites, in order to impart them with sufficient physical and mechanical characteristics and increase their compatibility without violating biodegradability.Methods. Reaction mixtures contained the elastic material NBR-28, various modifiers (sorbitan oleate, epoxidized soybean oil, siloxane rubber), and additional polymer components (ethylene–vinyl acetate copolymer and polybutylene adipate terephthalate). The mixtures were prepared in a PL 2200-3 plasticorder (Brabender, Russia) by pressing, holding the material at 180°C under pressure for 3 min followed by quenching in cold water. The surfaces of the films and plates of the mixtures were studied using an Axio Imager Z2m optical microscope (Carl Zeiss, Germany) with the Axio Vision software at 50× and 200× magnification in reflected light. The mechanical properties of materials under tension were measured using an Instron 3365 universal tensile testing machine (Instron, United Kingdom).Results. The role of modifiers and polymer additives in the PHB–NBR-28 composites and their influence on the morphology of mixtures, crystallinity, and mechanical characteristics were established. The introduction of modifiers made it possible to reduce the average particle size of the NBR-28 phase in the PHB matrix by 30–50%, additionally changing their morphology. In this case, the uniformity of particle distribution increased, having a positive effect on the mechanical characteristics of the systems.Conclusions. It was shown that the modifiers change the morphology of mixtures, reduce the average particle size of the NBR phase by 30–50%, and positively affect the strength of the systems. Owing to changes in the structure of their interfacial layers and, as a consequence, physical and mechanical characteristics, the resulting composites render suitable for use in reparative bone and dental surgery, as well as for creating wound healing materials.

Modification of Processability and Shear-Induced Crystallization of Poly(lactic acid).

We studied the rheological properties under both shear and elongational flow and crystallization behaviors after shear history for binary blends of poly(lactic acid) (PLA) and ethylene-vinyl acetate copolymer (EVA) with a slightly lower shear viscosity. EVA was immiscible with PLA and dispersed in droplets in the blend. The addition of EVA significantly reduced the shear viscosity, which is attributed to the interfacial slippage between PLA and EVA. In contrast, under elongational flow, the addition of EVA provided strain hardening in the transient elongational viscosity. Consequently, the degree of neck-in behavior in T-die extrusion, i.e., a decrease in the film width, was reduced with the high orientation of the PLA chains. Furthermore, it was found that the addition of EVA accelerated the shear-induced crystallization of PLA, although EVA showed no nucleating ability without a flow field. Because the EVA addition can improve the mechanical toughness, this modification technique is attractive for various industrial applications of PLA.

Investigation on underwater bonding strength and improvement mechanism of ethylene-vinyl acetate copolymer modified mortar

Investigation on underwater bonding strength and improvement mechanism of ethylene-vinyl acetate copolymer modified mortar

Creep lifetime of ethylene vinyl acetate co-polymer film after pre-load relaxation

Creep lifetime of ethylene vinyl acetate co-polymer film after pre-load relaxation

Biocomposites Based on Polyethylene/Ethylene–Vinyl Acetate Copolymer/Cellulosic Fillers

This work studied biocomposites based on a blend of low-density polyethylene (LDPE) and the ethylene–vinyl acetate copolymer (EVA), filled with 30 wt.% of cellulosic components (microcrystalline cellulose or wood flour). The LDPE/EVA ratio varied from 0 to 100%. It was shown that the addition of EVA to LDPE increased the elasticity of biocomposites. The elongation at break for filled biocomposites increased from 9% to 317% for microcrystalline cellulose and from 9% to 120% for wood flour (with an increase in the EVA content in the matrix from 0 to 50%). The biodegradability of biocomposites was assessed both in laboratory conditions and in open landfill conditions. The EVA content in the matrix also affects the rate of the biodegradation of biocomposites, with an increase in the proportion of the copolymer in the polymer matrix corresponding to increased rates of biodegradation. Biodegradation was confirmed gravimetrically by weight loss, an X-ray diffraction analysis, and the change in color of the samples after exposition in soil media. The prepared biocomposites have a high potential for implementation due to the optimal combination of consumer properties.

Performance of sandwich type fire-resistant flexible composite phase change material PEE@EBF for battery thermal management and runaway protection

Performance of sandwich type fire-resistant flexible composite phase change material PEE@EBF for battery thermal management and runaway protection

Effect of material properties and extrusion process parameters on permeability of etonogestrel in ethylene vinyl acetate copolymer (EVA) films

Ethylene vinyl acetate (EVA) copolymers have been extensively used in controlled drug delivery systems due to its good biocompatibility and tunable applicability based on simple variations in vinyl acetate (VA) content. We investigated impacts of polymer properties and extrusion process parameters of EVA on permeability of etonogestrel in EVA films. Among all factors studied, the VA content was the most dominant factor that controls drug permeability by affecting crystallinity of EVA. EVA molecular weight, drawing, and cooling of EVA during extrusion process exhibited less significant effects. The impacts of these factors on crystallinity, crystallite size, and degree of crystalline orientation of EVA were characterized using polarized light microscope (PLM), differential scanning calorimetry (DSC) and wide-angle X-ray scattering (WAXS). Based on solution-diffusion model, the mechanisms by which the crystalline properties controlled drug solubility and diffusivity in EVA were discussed. These results can be applied to investigate the effects of EVA material properties and manufacturing process conditions on drug release properties of reservoir-type EVA-based drug delivery systems designed with a rate-controlling EVA membrane.

Fabrication of high performance polypropylene based blends from ethylene vinyl acetate-based sole waste via solid-state shear Co-milling

Fabrication of high performance polypropylene based blends from ethylene vinyl acetate-based sole waste via solid-state shear Co-milling

Superhydrophobic Coating Based on Nano-Silica Modification for Antifog Application of Partition Glass

In this study, vinyl triethoxysilane (VTES), KH-560 and trimethylchlorosilane (TMCS) were used to modify the surface groups of commercially available nano-silica (SiO2, 50 nm), and ethylene vinyl acetate copolymer (EVA) was used as a film-forming agent. EVA/SiO2, EVA/V-SiO2, EVA/K-SiO2 and EVA/T-SiO2 coatings were prepared, respectively. The coatings were characterized by SEM, FTIR, TG and contact angle. It was found that when the mass percentage of SiO2 was 66 wt%, the hydrophobicity performance of the coating could be significantly improved by silica modification. Compared to the EVA/SiO2, the water contact angle (WCA) of the EVA/V-SiO2, EVA/K-SiO2 and EVA/T-SiO2 were increased by 24.0%, 14.4% and 24.6%, respectively. The FTIR results indicated that VTES, KH-560 and TMCS could effectively replace the -OH groups on the surface of the SiO2 after hydrolysis, resulting in the presence of water transport groups on the SiO2 surface. The TG results certified that TMCS had the highest substitution rate (24.6%) for the -OH groups on the SiO2 surface after the hydrolysis. Additionally, the SEM results indicated that T-SiO2 was more easily dispersed in the EVA film-forming agent, leading to a uniform micro–nano surface rough structure, which aligned with the Cassie–Wenzel model. The durability test had demonstrated that the EVA/T-SiO2 maintained its hydrophobic properties even after enduring 40,000 drops of water and the impact of 200 g of sand. Furthermore, it exhibited excellent resistance to acid corrosion, along with superior self-cleaning properties and an anti-fog performance. It also provided outstanding protection against high temperatures and UV radiation for outdoor applications.

Phase-Transition-Promoted Interfacial Anchoring of Sulfide Solid Electrolyte Membranes for High-Performance All-Solid-State Lithium Battery.

Solvent-free manufacturing is crucial for fabricating high-performance sulfide-electrolyte-based all-solid-state lithium batteries (ASSLBs), with advantages including side reaction inhibition, less contamination, and practical scalability. However, the fabricated sulfide electrolytes commonly suffer from brittleness, limited ion transport, and unsatisfactory interfacial stability due to the uncontrolled dispersion of the sulfide particles within the polymer binder matrix. Herein, a "solid-to-liquid" phase transition strategy is reported to fabricate flexible Li6PS5Cl (LPSCl) electrolytes. The polycaprolactone (PCL)-based binder (PLI) with phase-transition characteristics fills the gap of LPSCl particles and tightly grafts on the particle surface via ion-dipole interaction, bringing a thin and compact electrolyte membrane (80µm). The simultaneously high Li-ion conducting and electron insulating nature of PLI binder facilitates Li-ion transport and ensures good interfacial stability between electrolyte and anode. Consequently, the sulfide electrolyte membrane exhibits high ionic conductivity (8.5×10-4 S cm-1), enabling symmetric and full cells with 10 and 2.5 times longer cycling life compared with that of the cells with pristine LPSCl electrolyte, respectively. The demonstrated strategy is versatile and can be extended to ethylene vinyl acetate copolymer (EVA) that also brings enhanced electrochemical performance. The thin sulfide electrolyte with high interfacial stability potentially facilitates dendrite-free ASSLBs with high energy density.

Visible-light-driven Fe-catalyzed alkylation for synthesizing functionalized polyolefin elastomers as advanced encapsulants in photovoltaic modules

Visible-light-driven Fe-catalyzed alkylation for synthesizing functionalized polyolefin elastomers as advanced encapsulants in photovoltaic modules

XPS analysis of damp heat aged and fractured polymer/glass laminates

XPS analysis of damp heat aged and fractured polymer/glass laminates

An alternative filament fabrication method as the basis for 3D-printing personalized implants from elastic ethylene vinyl acetate copolymer

In this work, a novel tool for small-scale filament production is presented. Unlike traditional methods such as hot melt extrusion (HME), the device (i) allows filament manufacturing from small material amounts as low as three grams, (ii) ensures high diameter stability almost independent of the viscoelastic behavior of the polymer melt, and (iii) enables processing of materials with rheological profiles specifically tailored toward fused filament fabrication (FFF). Hence, novel materials, previously difficult to process due to HME limitations, become easily accessible for FFF for the first time. Here, we showcase the production of highly flexible drug-free, and drug-loaded filaments based on ethylene-vinyl acetate polymers with a vinyl acetate content of 28 w% (EVA28) and unprecedented high melt flow rates of up to 400 g/10 min. Owing to their low viscosity, FFF with low print nozzle sizes of 250 μm was achieved for the first time for EVA28. These small nozzle diameters facilitate 3D-printing of high-resolution structures in small-dimensional dosage forms such as subcutaneous implantable drug delivery systems, which can later be used for personalization. Consequently, the material portfolio for FFF is tremendously broadened, allowing material and formulation optimization toward FFF, independent of a preliminary extrusion process.

Intelligent Reversible Reconfigurable Metamaterials Based on a Two-Way Shape Memory Polymer.

The development of intelligent reversible reconfigurable metamaterials has great significance in constructing three-dimensional metamaterials and introducing reversible tunability into metamaterials. Here, we introduce an intelligent metamaterial consisting of a two-way shape memory polymer (2W-SMP) ethylene vinyl acetate copolymer (EVA) actuator substrate and a patterned flexible-rigid film. Mechanical buckling of the 2W-SMP substrate was controlled by thermal stimulation. This makes it possible to afford an ability to initiate 3D structure formation or shape reconfiguration remotely in an on-demand fashion. In addition, the shape of the 2W-SMP substrate is temperature-dependent, allowing repeatable reversible deformation through temperature control after a single programming. Therefore, the electromagnetic properties of metamaterials can also be repeatedly and reversibly tuned between 9.15 and 10.82 GHz. Experimental demonstrations include the deformation and tunable electromagnetic properties of intelligent reversible reconfigurable metamaterial cells. The results create many opportunities for advanced programmable three-dimensional metamaterials.

Study on the formation process of methane hydrates on the surface of wax crystals with pour point depressant

Study on the formation process of methane hydrates on the surface of wax crystals with pour point depressant

Durability Properties of Steel Textiles and Bonding Properties at the Interface of Steel Textiles with Reinforced Mortar-Reinforced Concrete Systems.

Aging and deterioration of building structures have been persistent concerns in the field of engineering. To address these challenges while supporting modern green and sustainable development goals, this study introduces an innovative reinforcement system that employs steel textiles as the primary reinforcing material. The steel textiles were engineered by optimizing the compatibility between steel fibers and a hot melt adhesive (HMA). These textiles were then used to reinforce concrete structures, creating a steel textile-reinforced mortar (STRM)-reinforced concrete system. The study also examined the durability of the steel textiles and the interfacial bonding performance within the STRM-reinforced concrete system. The results showed that the compatibility between steel fibers and ethylene vinyl acetate copolymer (HMA-2) is better, and the steel textiles prepared with it have superior hydrothermal and corrosion resistance. After the system had been maintained for 28 days, the overall flexural strength of the STRM-reinforced concrete system was increased by 100.03%, the interfacial shear load by 49.54%, the interfacial shear stiffness by 61.2%, and the positive tensile bond performance by 26.1%. This proves that STRM has a good reinforcement effect on the concrete reinforcement system.

MoS2@Fe3O4 prepared by γ-ray in situ reduction for enhancing the fire safety and mechanical properties of EVA/MCA composites

MoS2@Fe3O4 prepared by γ-ray in situ reduction for enhancing the fire safety and mechanical properties of EVA/MCA composites

Enhancing toughness in cement-based composites: Unraveling the composite effect mechanisms of polymers and fibers through physic testing and molecular dynamics simulations

Enhancing toughness in cement-based composites: Unraveling the composite effect mechanisms of polymers and fibers through physic testing and molecular dynamics simulations