pps proceeding - Abstract Preview
pps proceeding
Symposium: Recycling
Oral Presentation
 
 

Design of stimuli triggered smart composite materials with enhanced recyclability and selfhealing properties

Radl Simone Viola (1)*, Griesser Thomas (2), Kreimer Manuel (1), Oesterreicher Andreas (2), Kern Wolfgang (2), Schlögl Sandra (1)

(1) Polymer Competence Center Leoben GmbH - Styria - Austria, (2) Chair of Chemistry of Polymeric Materials, University of Leoben - Styria - Austria

This contribution highlights new approaches towards the preparation of smart composite materials with switchable mechanical properties triggered by external stimuli of different nature. Photoswitchable mechanical properties in thermoset resins are obtained by the immobilization of UV labile crosslinks in the polymer backbone. Due to the photoinduced cleavage reaction of the o-nitrobenzyl ester groups a dramatic loss in the storage modulus and the glass transition temperature of the cured resin is observed upon UV illumination. Futhermore enhanced recyclability is confirmed by single fibre pull-out tests which suggest that the adhesion strength between the cured resin and glass fibers can be reduced significantly upon UV illumination. Besides photocleavable reactions, the present work further focuses on the design of reversibly crosslinkable epoxy-based networks that undergo bond formation and cleavage in response to external stimuli. New anthracene derivatives have been synthesized and characterized for the use as a crosslinker in epoxy-based resin formulations. Upon UV irradiation a crosslinking of anthracene groups in the resin occurs, whilst a subsequent thermal step leads to a cleavage of the dimer. UV-VIS measurements confirmed that the reversibility of this photodimerization reaction within the thermosetting resin exceeds 80%.The UV crosslinked and thermal cleaved resin samples were characterized using mechanical testing methods over several repeated repair cycles. The results give evidence to a significant loss in the mechanical properties after thermal treatment while a repeated UV irradiation leads to a recovery in the mechanical properties. The materials show repeated healability of the photocrosslinked materials with healing efficiencies of 30% and 70% in terms of storage modulus and flexural stress.