17. Recycling of sulfur cross-linked natural rubber (NR) using supercritical carbon dioxide

Published Date
Chemistry, Manufacture and Applications of Natural Rubber
2014, Pages 436–451, doi:10.1533/9780857096913.3.436

• Author 

• Y. Ikeda

Abstract:

This chapter reviews an efficient recycling process using supercritical carbon dioxide (scCO₂) for sulfur cross-linked natural rubber (NR). The role of scCO₂ in the devulcanization process is also described; scCO₂ works very well in facilitating the penetration of the most effective devulcanizing reagent, diphenyl disulfide, into NR vulcanizate. Neither carbon black nor silica can prevent the decross-linking reaction of NR vulcanizate in scCO₂. Of the several recycling technologies available, the utilization of scCO₂ is possibly the most practical and useful process. Diphenyl disulfide is, however, not reactive to mono-sulfide. A selective decross-linking reaction for mono-sulfidic linkage in NR vulcanizate, therefore, needs to be found in order to further develop the recycling process for sulfur cross-linked NR.

Key words

• rubber recycling
• devulcanization
• natural rubber
• supercritical carbon dioxide
• diphenyl disulfide

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