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Self-healing elastomers - healing functionalisation by polymer analogous side-group modification

: Nellesen, A.; Tapavicza, M. von; Schmidt, A.M.

European Society for Composite Materials:
17th European Conference on Composite Materials, ECCM 2016. Proceedings : 26-30th June 2016, Munich, Germany, CD-ROM
Munich, 2016
ISBN: 978-3-00-053387-7
European Conference on Composite Materials (ECCM) <17, 2016, Munich>
Conference Paper
Fraunhofer UMSICHT Oberhausen ()

Recently, elastomers that possess a self-healing capability gathered more and more attention in scientific research. Different principals were applied to trigger the restoration of mechanical properties and various characterization methods were applied to prove the concept. Based on biological self-repairing mechanisms, we have developed and realised several self-healing strategies for elastomers. Biological role models were analysed concerning their healing behaviour by the Plant Biomechanics Group Freiburg. Ionomeric modification has proven to be most advantageous, especially for elastomers. Based on pure materials, we applied different polymer-analogous side-group modifications followed by ionisation of incorporated side-groups, the so called neutralisation step. Modified polymers are EPDM (ethylene propylene diene-terpolymer type M), NBR (nitrile butadiene rubber) and SEBS (styrene ethylene butylene stryrene). Most positive self-healing results were observed for modified NBR-grades. After a macroscopic cut, reassembling, storage at 55°C for 24 h and subsequent tensile testing, samples made from unvulcanised material showed a recovery of 100 % (elongation at break) and 80 % (breaking stress). Vulcanised samples, after the same treatment, showed an elongation at break of 18 %, breaking stress of 15 %. This implicates that healing effectiveness strongly depends on degree of vulcanisation, neutralisation degree and healing temperature.