Elasticity recovery of crosslinked EPDM: influence of the chemistry and nanofillers
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Elasticity recovery of crosslinked EPDM: influence of the chemistry and nanofillers Cindy Le Hel 1 & Véronique Bounor-Legaré 1 & Antoine Lucas 2 & Anthony Thèvenon 2 & Philippe Cassagnau 1 Received: 27 June 2020 / Revised: 25 September 2020 / Accepted: 28 September 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The objective of this work was to study the elastic recovery of EPDM samples crosslinked either by a phenolic resin (resol) or by a radical peroxide (dicumyl peroxide, DCP). From compression set experiments, it was observed that radically crosslinked EPDMs have better elastic recovery properties. On the other hand, for the same crosslinking density, radically crosslinked EPDM shows better compression set than EPDM crosslinked with phenolic resins. The Chasset-Thirion equation was then used to successfully fit the experimental relaxation curves. As a notable result, the preferential statistics of a peroxide-crosslinked network over a phenolic resin (resol) showed that better elastic recovery properties were obtained. Finally, the influence of fillers (carbon black and silica) was also studied. Carbon black with DCP crosslinking was shown to improve elasticity recovery whereas silica fillers lead to worse properties. It was then assumed that the interaction between particle surface and a voir comme dans autre publi à modifier ce crosslinking agent induced crosslinking gradients in the inter-particle volume. Keywords Compression set . EPDM . Crosslinking . Elasticity recovery
Introduction Ethylene-propylene-diene terpolymers (EPDM) are well known and used in industrial applications such as sealing in automotive materials. In fact, these terpolymers combine a saturated polymer chain with pendant residual unsaturated groups. As a result, they are more resistant to oxygen, ozone, UV, and heat than basic polydiene elastomers (Ning et al. 2018). However, in terms of viscoelasticity, the property of recovering elasticity after a long period of application is required. Therefore, most EPDM applications require its chemical crosslinking in order to give it permanently elastic
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00397-020-01246-0) contains supplementary material, which is available to authorized users. * Philippe Cassagnau [email protected] 1
Ingénierie des Matériaux Polymères, CNRS, Univ-Lyon, Université Claude Bernard Lyon 1, UMR 5223, 15 Bd Latarjet, 69622 Villeurbanne Cedex, France
2
Hutchinson, Centre de Recherche, Rue Gustave Nourry - B.P. 31, 45120 Chalette-sur-Loing, France
properties. In addition, nanofillers such as carbon black are often added to increase the mechanical properties. Very few dienes are currently used in commercial EPDM: 5-ethylidene-2-norbornene (ENB), dicyclopentadiene, and 5vinylidene-2-norbornene. The chemical crosslinking reaction is then achieved using mainly three types of crosslinking agents: sulfur, peroxides, and alkylphenol-formaldehyde resins (resols).
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