•An effective and synergistic P/N-containing advance nano flame retardant (IL-BP) is successfully fabricated via non-covalently functionalization.•The fire safety of the EVA matrix has significantly ...improved with a low loading of 1.5 wt.% IL-BP, achieving a UL-94V-0 rating.•The IL-BP/EVA composite demonstrates improved tensile strength and elongation at break of 25 % and 9.6 % upon the addition of 1.5 wt.% IL-BP.
The development of flame-retardant polymer materials play a vital role in reducing fire hazards and protecting both lives and property. Black phosphorus (BP) is an extremely promising flame retardant since its synergistic flame retardancy with different modifiers. Nevertheless, the issue of unven dispersion within the polymer matrix has severely restricted its practical applications. Herein, BP nanosheets functionalized with ionic liquid (IL-BP) were prepared and then compounding with EVA to improve the mechanical and the flame-retardant properties of EVA matrix. The results demonstrated enhanced compatibility of IL-BP nanosheets within the EVA matrix, leading to the 1.5 %IL-BP/EVA composite displayed a 25 % and 9.6 % increase in tensile strength and elongation at break, respectively. Remarkably, the flammability test results demonstrated that the 1.5 %IL-BP/EVA sample featured a significant decrease of 18.1 % and 21.5 % in total heat release (THR) and peak heat release rate (PHRR), respectively. Meanwhile, the composite also achieved a V-0 rating in UL-94 test and demonstrated superior resistance to melt dripping. The flame-retardant mechanisms of IL-BP/EVA composites in both gas phase and condensed phase were studied. This work provides a promising strategy to design synergetic flame retardants that simultaneously enhanced the fire safety and mechanical properties of EVA.
Photovoltaic (PV) modules are subject to climate-induced degradation that can affect their efficiency, stability, and operating lifetime. Among the weather and environment related mechanisms, the ...degradation mechanisms of the prominent polymer encapsulant, ethylene-vinyl-acetate copolymer (EVA), and the relationships of the stability of this material to the overall reliability of Si-based PV modules were addressed. The EVA function and properties correlated to its deterioration factors as temperature, moisture, and ultraviolet radiation (UV) were discussed in this work. The main objective of this study is to review the literature on EVA encapsulation and its degradation, which promotes the loss in performance of the PV module. The deleterious effects on EVA such as photodegradation, moisture, delamination, bubble formation and potential induced degradation (PID), their relationship with the polymer structure, chemical, mechanical, optical and electrical properties are approaches carried out in this review. This paper also provides a brief review of the developing field of EVA composites technology aiming at higher performance materials.
Silicone rubber/ethylene‐vinyl acetate copolymer/magnesium sulfate whisker composites containing ethylene‐acrylic acid copolymer (MS/SR/EVM/EAA) as a compatibilizer were successfully prepared. ...Moreover, the magnesium sulfate whisker surface was modified with 3 wt% of silane coupling agent (KH570), resulting in composites including (unmodified magnesium sulfate whisker) uMS/SR/EVM, (modified magnesium sulfate whisker) mMS/SR/EVM, and mMS/SR/EVM/EAA were compared. The values of thermal decomposition activation energy (Ea) calculated by the two different methods (Kissinger and Friedman methods) show that the composites filled with 5 and 20 phr whiskers have lower values of activation energy (Ea) than the SR/EVM blend. The tensile strength of composites with a 5 phr modified whisker is 14.5 MPa, which is higher than that of the SR/EVM blend and uMS5/SR/EVM composite. The tear strength of the composite with 20 phr mMS is 51.6 kN m−1, much higher than that of the composite with 20 phr uMS and SR/EVM blend. The mechanical properties were also investigated after thermal aging of the composites at 85°C for 48 h. The thermal conductivity of the composites with high filler loading was studied.
MS whisker modified by a coupling agent Step 1: KH570, Step 2: interfacial interaction between modified. whisker, EAA, and SR/EVM matrix.
Ethylene vinyl acetate copolymer (EVA) is widely applied in many important fields, but its broader utility is impeded by its flammability. To address this problem, the pre-acidified kaolinite (AKaol) ...by sulfuric acid was further dealt with TiO2 loading and Zn2+ doping to obtain Zn/TiO2@AKaol to improve the flame retardancy and smoke suppression of EVA composites containing intumescent flame retardants (IFR) typically. The results showed that the addition of 1 wt% Zn/TiO2@AKaol improved the flame retardancy and reduced the smoke release of EVA/IFR composite. The limiting oxygen index (LOI) value of the EVA/IFR composite containing Zn/TiO2@AKaol increased to 32.7 % from 27.3 % of EVA/IFR composite. In the cone calorimeter test (CCT), the peak heat release rate (pHRR) and total heat release (THR) values were reduced to 297.5 kW/m2 and 98.8 MJ/m2 from the 409.9 kW/m2 and 109.3 MJ/m2 of EVA/IFR composite, respectively. Meanwhile, the values of total smoke production (TSP) in the CCT and smoke density tests in building materials were reduced to 13.5 m2 and 33.39 % of EVA/IFR/Zn/TiO2@AKaol composite from 18.4 m2 and 63.91 % of EVA/IFR composite, respectively. Based on the mechanism analysis, it was proposed that Zn/TiO2@AKaol not only promoted the production of P· in advance, but also increased a cross-linked structure char in the condensed phase to achieve flame retardancy and smoke suppression of EVA composites.
•MEG/PPA shows amazingly high flame-retardant efficiency to EVA.•Incorporating only 5 wt% MEG/PPA can endow EVA with V-0 rating.•The flame-retarded EVA displays even better processability than virgin ...EVA.•The flame-retarded EVA has the same mechanical property as that of neat EVA.•High-quality expanded char with large volume leads to the high efficiency.
The most conspicuous problem regarding fire retardation of ethylene vinyl acetate (EVA) copolymer is that the flame-retardant efficiency of traditional fire retardants is very low. How to achieve high-efficient flame retardation has long been a big challenge. Herein, polyurea-modified microencapsulated expandable graphite (MEG) was synthesized through in-situ polymerization, and it was found that the proper combination of MEG and polyphosphoric acid (PPA) exhibits an unexpectedly high flame-retardant efficiency to EVA. The incorporation of just 5 wt% MEG/PPA enables EVA to achieve V-0 rating in UL-94 flammability test, increases its limiting oxygen index from 19.3 % to 25.7 %, and reduces its peak heat release rate by 72 % during combustion. The EVA/MEG/PPA composite, containing 5 wt% MEG/PPA, not only demonstrates improved fire retardancy, smoke suppression, and processability compared to virgin EVA, but also maintains good electrical insulation, water resistance, and mechanical properties. The high fire-retardant efficiency is ascribed to the larger expansion volume of MEG and the formation of high-quality intumescent char, which shield the polymer from burning. This work renders a simple and cheap approach for development of high-efficient flame-retarded EVA with good processability and mechanical property simultaneously.
This work deals with the development of oleogels based on conventional (SO) and high-oleic sunflower (HOSO) vegetable oils and ethylene–vinyl acetate copolymer (EVA) for lubricant applications. ...Particularly, the influence of EVA concentration on the tribological, rheological properties and microstructure of these oleogels was analyzed. The results showed that the evolution of linear viscoelasticity functions was similar to that found for lithium greases. The different fatty acid profile in vegetable oils tested exerted an important influence on friction and wear in the ball-on-plates contact. The friction coefficient values became lower when EVA content was decreased. The wear marks obtained after the frictional tests for EVA–SO oleogels significantly reduced the wear scars versus EVA–HOSO oleogels and it was similar to commercial grease.
•Development of oleogels based on vegetable oils and EVA copolymer.•Influence of the EVA content compared with analyzed commercial grease.•Rheological and thermal characterization of oleogels.•Obtaining values for friction coefficients and wear in the ball-on-plates contact.
▶ This work deals with the modification of vegetable oils viscosity for bio-lubricant applications. ▶ Use of EVA copolymer allows improving viscosity data for conventional vegetable oils studied. ▶ ...Viscosity increments up to 330–420% respecting the original oil have been obtained for these vegetable oils/EVA blends. ▶ Ternary blends of high-oleic sunflower oil, castor oil, and EVA may be used to design enhanced bio-lubricant formulations.
During these last years, special attention has been paid to the protection of the environment against pollution exerted by lubricants and hydraulic fluids based on mineral oils. Thus, vegetable oil-based lubricants are being actively demanded for many green industrial activities. Although vegetable oils have some excellent properties for their potential use as lubricants, some inconveniences should be technologically improved, i.e. limited range of viscosities available. Consequently, environmental friendly viscosity modifiers should be included in the lubricant formulation. In this paper, ethylene–vinyl acetate copolymer (EVA) has been successfully tested as viscosity modifier for several common vegetable oils, yielding potentially environmental friendly lubricants for some applications. EVA addition always yields an important increase in vegetable oil viscosity. The most important viscosity increments have been found for low-viscosity vegetable oils, i.e. sunflower oil (SO), high-oleic sunflower oil (HOSO) and soybean oil (SYO), at moderate temperatures. Viscosity increments up to 330–420% respecting the original oil have been obtained for these vegetable oil/EVA blends at 40
°C. On the contrary, the lowest increments correspond to castor oil/EVA blends, mainly at low temperature. Furthermore, ternary blends of high-oleic sunflower oil, castor oil (CO) and EVA may be used to design enhanced bio-lubricant formulations for some specific applications. In this sense, some CO/HOSO/EVA ternary blends (CO/HOSO weight ratios >1) show kinematic viscosities, at 40
°C, higher than 320
cSt, which may be considered a threshold viscosity value for gearboxes and four-strokes engine applications.
The blends of ethylene‐acrylic acid copolymer (EAA) and ethylene‐vinyl acetate copolymer (EVA) with triple‐shape memory effect was fabricated using dicumyl peroxide (DCP) as the crosslinking agent. ...The mechanical properties and thermal properties were carried out by the universal testing machine and differential scanning calorimetry, respectively. Furthermore, the triple‐shape memory behavior of the prepared EAA/EVA blends and EAA/EVA blends crosslinked by DCP were characterized by the shape fixity ratio and shape recovery ratio which were used as the evaluation standards. The blends exhibited the prominent shape memory properties, for example, the first shape fixity ratio was about 90%, the second shape fixity ratio was about 90%, while the first shape recovery ratio was about 100% and the second shape recovery ratio was about 90%. Moreover, the material had a stable shape memory behavior. This novel shape memory polymers expected to have a potential application in smart devices.
Schematic illustration of shape memory mechanism of EAA/EVA blends.
Rare studies have investigated on the 2‐way shape memory crosslinked blends with multiple shape memory behavior up to date. To consider the merit of commercial cost‐competitive crystalline polymers, ...ethylene vinyl‐acetate copolymer (EVA)/polycaprolactone (PCL) blends (60/40 and 30/70) were peroxide‐cured to form the 2‐way multi‐shape memory crosslinked blends using a melt‐blending method. Both resins were selected to have a similar controlled crosslinking degree, which allowed us to distinctly evaluate their actuation contributions from the cooling‐induced elongation (crystallization) and from the entropy‐driven elongation during cooling process, respectively. In the 2‐way process for the 60/40 system, 2 respective peaks contributed from the cooling‐induced crystallization of EVA and PCL in the cooling curves based on the strain derivate rates at various temperatures were observed. After the cooling process under the loading stress of 150 kPa, the 2‐step heating‐induced contraction process with increasing temperature started at 54.1°C above the melting temperature of PCL at 52.3°C and EVA at 78.3°C, demonstrating 2‐way multi‐shape memory behavior. The multi‐step behavior was more prominent at higher PCL composition and higher load for the 30/70 system. It was found that the entropy‐driven contribution to the overall actuation magnitude increased with increasing nominal loads due to the increased orientation of molecular networks in the blends. The current approach offers numerous possibilities in preparing 2‐way multi‐shape memory crosslinked blends.
The melt-mixing method was used to obtain nanocomposites of ethylene vinyl acetate copolymer (EVA) with 1, 3 or 5wt% of hydrophilic zinc oxide (ZnO) nanoparticles. The contact angle, barrier and ...antimicrobial properties of the obtained composites were investigated. The nanocomposites were characterized by better hydrophilic and barrier properties, as evidenced by, respectively, a smaller contact angle and lower water vapor permeability and water absorption compared to EVA, which can be explained by the formation of hydrogen bonds between EVA and ZnO. In addition, the composites were characterized by greater bactericidal activity against E. coli and S. aureus. The optimal physical and microbial properties were obtained with 3 wt% ZnO content.
