Peroxide-based crosslinking of solid silicone rubber: part II: The counter-intuitive influence of dicumylperoxide concentration on crosslink effectiveness and related network structure

Maurício Azevedo, Anna-Maria Monks, Roman Kerschbaumer, Sandra Schlögl, K. Saalwächter, Matthias Walluch, G. Consolati, Clemens Holzer

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Application of elastomers in general demands the conversion of their soluble networks into crosslinked structures. This abrupt change causes several modifications, both in the atomic/molecular level and at the macro-scale. In this study, solid silicone rubber (high molecular weight poly(dimethylsiloxane)), was crosslinked with dicumylperoxide (DCP), a widely used crosslinking agent by the rubber industry. The changes caused by different DCP concentrations were investigated, aiming to bring attention to the molecular transformations, usually neglected when processing-oriented studies are conducted. DCP concentration showed a limited contribution to the network's molecular dynamics, which was found to be mainly dominated by entanglements. The dominance of entanglements over other molecular constraints, like crosslink points, justifies the threshold and counter-intuitive behavior of tensile and hardness properties. However, differences were found in the crystallization ability after crosslinking, when the more crosslink points were introduced, the lower the crystallinity was and the less stable the PDMS crystallites were. In addition to providing a deeper understanding of an industrially applied rubber system n terms of the effective concentration of DCP, and the reasoning behind such concentration, the findings of this study add to the state-of-the-art comprehension of elastomeric networks, and how they behave on a molecular level.
Original languageEnglish
Article numbere54111
Number of pages17
JournalJournal of applied polymer science
Volume140.2023
Issue number31
DOIs
Publication statusPublished - 15 Aug 2023

Bibliographical note

Publisher Copyright:
© 2023 The Authors. Journal of Applied Polymer Science published by Wiley Periodicals LLC.

Keywords

  • crosslink density
  • crosslinking
  • dicumylperoxide
  • free volume
  • network morphology
  • silicone

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