Turning Vulcanized Natural Rubber into a Self-Healing Polymer: Effect of the disulfide/polysulfide Ratio

Marianella Hernández, Antonio M. Grande, Wilma Dierkes, Johan Bijleveld, Sybrand van der Zwaag, Santiago J. García

Research output: Contribution to journalArticleAcademicpeer-review

69 Citations (Scopus)

Abstract

A self-healing sulfur vulcanized natural rubber (NR) is here reported using the common ingredients in a traditional NR formulation. The dynamic character of the di- and polysulfide bonds naturally present in covalently cross-linked rubbers was found to be responsible for the healing ability and the full recovery of mechanical properties at moderate temperatures provided the material was employed in a nonfully cured starting state. Results show that a compromise between mechanical performance and healing capability can be reached by tailoring the amount of sulfur, the cross-linking density, and the disulfide/polysulfide ratio. The healing efficiency was found to depend on the postcuring storage time, the time between damage creation and re-establishment of mechanical contact, and the actual healing time. Furthermore, a dedicated electron spin resonance (ESR) test allowed establishing the underlying healing principle based on temperature-induced free sulfur radicals. The main observations presented here can serve as the basis for the design and preparation of other self-healing polymers with long-term durability based on di-/polysulfide bridges and other reversible moieties.
Original languageEnglish
Pages (from-to)5776-5784
Number of pages10
JournalACS sustainable chemistry & engineering
Volume4
Issue number10
DOIs
Publication statusPublished - 6 Sep 2016

Keywords

  • Vulcanized natural rubber
  • Degree of curing
  • Self-healing
  • Disulfides
  • Polysulfides
  • Elastomer
  • Time dependence
  • Electron spin resonance

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