scholarly journals Coupling Dynamic Covalent Bonds and Ionic Crosslinking Network to Promote Shape Memory Properties of Ethylene-vinyl Acetate Copolymers

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 983 ◽  
Author(s):  
Wenjing Wu ◽  
Sreeni Narayana Kurup ◽  
Christopher Ellingford ◽  
Jie Li ◽  
Chaoying Wan
Keyword(s):  
Tensile Strength ◽  
Shape Memory ◽  
Vinyl Acetate ◽  
Mechanical Performance ◽  
Memory Performance ◽  
Ethylene Vinyl Acetate ◽  
Crosslinking Density ◽  
Melt Processing ◽  
Covalent Bonds ◽  
Shape Memory Properties

Dynamic crosslinking networks based on Diels–Alder (DA) chemistry and ionic interactions were introduced to maleic anhydride modified ethylene-vinyl acetate copolymer (mEVA) via in situ melt processing. The dual dynamic crosslinking networks were characterized by temperature-dependent FTIR, and the effects on the shape memory properties of mEVA were evaluated with dynamic mechanical thermal analysis and cyclic tensile testing. A crosslinking density was achieved at 2.36 × 10−4 mol·cm−3 for DA-crosslinked mEVA; as a result, the stress at 100% extension was increased from 3.8 to 5.6 MPa, and tensile strength and elongation at break were kept as high as 30.3 MPa and 486%, respectively. The further introduction of 10 wt % zinc methacrylate increased the dynamic crosslinking density to 3.74 × 10−4 mol·cm−3 and the stress at 100% extension to 9.0 MPa, while providing a tensile strength of 28.4 MPa and strain at break of 308%. The combination of reversible DA covalent crosslinking and ionic network in mEVA enabled a fixing ratio of 76.4% and recovery ratio of 99.4%, exhibiting an enhanced shape memory performance, especially at higher temperatures. The enhanced shape memory and mechanical performance of the dual crosslinked mEVA showed promising reprocessing and recycling abilities of the end-of-life products in comparison to traditional peroxide initiated covalent crosslinked counterparts.

scholarly journals Wastes from Agricultural Silage Film Recycling Line as a Potential Polymer Materials

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1383
Author(s):  
Jerzy Korol ◽  
Aleksander Hejna ◽  
Klaudiusz Wypiór ◽  
Krzysztof Mijalski ◽  
Ewelina Chmielnicka
Keyword(s):  
Vinyl Acetate ◽  
Thermal Performance ◽  
Mechanical Performance ◽  
Ethylene Vinyl Acetate ◽  
Tensile Tests ◽  
Solid Particles ◽  
Polymer Materials ◽  
Slight Reduction ◽  
Scanning Calorimetry ◽  
Crystallinity Degree

The recycling of plastics is currently one of the most significant industrial challenges. Due to the enormous amounts of plastic wastes generated by various industry branches, it is essential to look for potential methods for their utilization. In the presented work, we investigated the recycling potential of wastes originated from the agricultural films recycling line. Their structure and properties were analyzed, and they were modified with 2.5 wt % of commercially available compatibilizers. The mechanical and thermal performance of modified wastes were evaluated by tensile tests, thermogravimetric analysis, and differential scanning calorimetry. It was found that incorporation of such a small amount of modifiers may overcome the drawbacks caused by the presence of impurities. The incorporation of maleic anhydride-grafted compounds enhanced the tensile strength of wastes by 13–25%. The use of more ductile compatibilizers—ethylene-vinyl acetate and paraffin increased the elongation at break by 55–64%. The presence of compatibilizers also reduced the stiffness of materials resulting from the presence of solid particles. It was particularly emphasized for styrene-ethylene-butadiene-styrene and ethylene-vinyl acetate copolymers, which caused up to a 20% drop of Young’s modulus. Such effects may facilitate the further applications of analyzed wastes, e.g., in polymer film production. Thermal performance was only slightly affected by compatibilization. It caused a slight reduction in polyethylene melting temperatures (up to 2.8 °C) and crystallinity degree (up to 16%). For more contaminated materials, the addition of compatibilizers caused a minor reduction in the decomposition onset (up to 6 °C). At the same time, for the waste after three washing cycles, thermal stability was improved. Moreover, depending on the desired properties and application, materials do not have to go through the whole recycling line, simplifying the process, reducing energy and water consumption. The presented results indicate that it is possible to efficiently use the materials, which do not have to undergo the whole recycling process. Despite the presence of impurities, they could be applied in the manufacturing of products which do not require exceptional mechanical performance.

Mechanical and morphological properties of modified halloysite nanotube filled ethylene-vinyl acetate copolymer nanocomposites

2018 ◽  
Vol 38 (3) ◽  
pp. 271-279 ◽  
Author(s):  
Suvendu Padhi ◽  
P. Ganga Raju Achary ◽  
Nimai C. Nayak
Keyword(s):  
Vinyl Acetate ◽  
Tensile Modulus ◽  
Ethylene Vinyl Acetate ◽  
Crosslinking Density ◽  
Weight Percent ◽  
Halloysite Nanotubes ◽  
Morphological Properties ◽  
Casting Method ◽  
Solution Casting Method ◽  
Acetate Copolymer

AbstractHalloysite nanotubes (HNTs) were modified by γ-methacryloxypropyltrimethoxysilane (γ-MPS) as it interacts with the aluminol and silanol groups of HNTs present at the edges and surfaces of HNTs. The polymer composites were prepared by means of the solution casting method with ethylene-vinyl acetate (EVA) copolymer having 45% vinyl acetate (VA) content with different weight percent of modified HNTs (m-HNTs). The modification of the HNTs by γ-MPS increases the interfacial and inter-tubular interactions and the degree of dispersion of the HNTs within the EVA matrix which manifest from increase in crosslinking density. The mechanical properties such as tensile strength, tensile modulus and tear strength of nanocomposites were found to increase because of m-HNT. The glass transition temperature (Tg) and the crystalline percentage decreases for EVA/m-HNT nanocomposites were due to the strong interaction between EVA matrix and filler. Also, the EVA/m-HNT nanocomposites exhibited better thermal stability due to the strong inter-tubular interaction.

Effect of Organo-Shell Materials on Compatibility of the Hydrotalcite Flame Retardant in Ethylene Vinyl Acetate

2019 ◽  
Vol 19 (11) ◽  
pp. 7476-7486
Author(s):  
Jinze Du ◽  
Hongyan Zeng ◽  
Enguo Zhou ◽  
Bo Feng ◽  
Chaorong Chen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Tensile Strength ◽  
Vinyl Acetate ◽  
Md Simulation ◽  
Ethylene Vinyl Acetate ◽  
Flame Retardance ◽  
Strength Tests ◽  
Intrinsic Correlation

The microcapsule nanoparticles were prepared by in-situ copolymerization of hydrotalcites (MAH) with the polymer (MF, PF, PS and PU) monomers, respectively, where the MF-wrapped MAH (MAH@MF) had the best monodispersity. The composites of the microcapsules and EVA were prepared by incorporating the microcapsule nanoparticles into ethylene vinyl acetate (EVA), respectively. To further understand the intrinsic correlation between microcapsule fillers and EVA matrix, molecular dynamics (MD) simulation was introduced to qualitatively analyze the contribution of microcapsule fillers on improving compatibility and mechanical properties of the EVA matrix. The compatibility of microcapsule nanoparticles with EVA matrix were detected in sequence through SEM, DSC and tensile strength tests. And the combustion, thermal behavior and flame retardance were also characterized by TG analyses as well as LOI and UL-94 level. As a result, the MAH@MF filler had the best performances in improving the flame retardancy and mechanical properties among the microcapsule fillers, attributed to high compatibility of the MAH@MF and EVA matrix, which made uniform distribution of the MAH@MF filler due to the reciprocity of triazine functional ring with vinyl acetate linkages.

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