Dataset Information

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

ABSTRACT: 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.

SUBMITTER: Wu W

PROVIDER: S-EPMC7240482 | biostudies-literature | 2020 Apr

REPOSITORIES: biostudies-literature

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

Wu Wenjing W Narayana Kurup Sreeni S Ellingford Christopher C Li Jie J Wan Chaoying C

Polymers 20200423 4

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<sup>-4</sup> mol·cm< ...[more]

PMID: 32340183

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Project description:BackgroundSports mouthguards, worn in the oral cavity to prevent sports injuries, are constantly exposed to various microorganisms that cause oral infections. Hence, the optimal cleaning methods for sports mouthguards have been thoroughly examined. In this study, we evaluated the efficiency of cleaning effects with a mouthguard cleaner (MC) on microbial biofilm formation in sports mouthguards in vitro and in vivo.MethodsWe evaluated the cleaning effects of the discs produced by ethylene-vinyl acetate (EVA) on bacterial biofilms formed by the commensal bacterium Streptococcus oralis, the cariogenic bacterium Streptococcus mutans, and the opportunistic pathogen Staphylococcus aureus in vitro. EVA discs with biofilm were subjected to sterile distilled water (CTRL) and ultrasonic washing (UW), followed by treatment with MC and sodium hypochlorite (NaClO) as positive controls. Thereafter, the viable bacterial cell counts were determined. The bacteria adhering to the sheets before and after the treatment were observed under an electron microscope. The degree of cleanliness and measurement of viable microbial cell counts for total bacteria, Streptococci and Candida, opportunistic fungi, were evaluated on the used experimental sports mouthguards with and without UW and MC treatment in vivo.ResultsThe number of bacterial cells significantly decreased against all the tested biofilm bacteria upon treatment with MC, compared with CTRL and UW. Electron microscopy analysis revealed the biofilm formation by all bacteria on the EVA discs before cleaning. We observed fewer bacteria on the EVA discs treated with MC than those treated with CTRL and UW. Furthermore, the degree of cleanliness of the used experimental sports mouthguards cleaned using MC was significantly higher than that of the CTRL-treated mouthguards. Moreover, the viable microbial cell counts on the used experimental sports mouthguard were considerably lower than those on the CTRL ones.ConclusionThe cleaning effect of MC against oral bacteria was more effective than that of UW. MC treatment might have a potential future application as a cleaning method for sports mouthguards to protect athletes from oral infection.

Dataset Information

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

Publications

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

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