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Explore trends in tire recycling alternatives like devulcanization and fine grinding for future sustainability and market expansion. Learn about the challenges and technological advancements in converting used tires back into high-quality materials.
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Progress and hurdles in tire recycling Wilma Dierkes University of Twente Enschede the Netherlands H. van Hoek S. Saiwari J. Noordermeer A. Blume
Progress and hurdles in tire recycling Outlook Analysis INTRODUCTION Filler systems Future developments Recycling alternatives Passenger car tire elastomers Summary & Acknowledgements Whole passenger car tire rubber
Introduction Trends in tires & sustainability R&D: Number of patents on… China EU Publication date Publication date USA http://www.tirereview.com/wp-content/uploads/Articles/02_01_2013/109978febcovera_00000060668.jpg Korea http://www.hankooktire.com/global/tires-services/technology/tire-labeling/overview/_jcr_content/par/image_0.img.jpg/1424738449507.jpg Japan https://media.licdn.com/mpr/mpr/AAEAAQAAAAAAAAfBAAAAJGRiMDc3YTc5LWMzOTQtNDEwZS05ZjgwLWZiMWFlMzQwZjRlNA.jpg
Introduction Recycling alternatives Cradle to Cradle DEVULCANIZATION Fine GRINDING http://wdo.ca/Portals/_default/Skins/wdo/sliderimg/usedtires.jpg PYROLYSIS or other processes Cradle to cradle via … http://tyrepyrolysisplants.net/wp-content/uploads/2015/04/usedtirespyrolysis.jpg
Introduction Recycling alternatives Cradle to Cradle DEVULCANIZATION http://wdo.ca/Portals/_default/Skins/wdo/sliderimg/usedtires.jpg http://tyrepyrolysisplants.net/wp-content/uploads/2015/04/usedtirespyrolysis.jpg
Introduction Status of recycling alternatives ‘Tires back into tires’: The only way to considerably broaden the market for recycled rubber Devulcanizate • Technology Readiness Levels (TRL): - Passenger car tire rubber: TRL5-6 (technology demonstration) - Truck tire rubber: TRL 7-8 (system development) • Concentration of devulcanizate in tire compounds: a multitude of current concentrations (depending on the compound type) • Technology Readiness Levels (TRL): - No significant development potential of conventional technologies (batch, long residence time, high temperatures) - Improvements by after-treatments - New technologies! • Large-scale application in tires only possible with significant quality improvements Pyrolysis Grinding • Technology available, also for very fine powder • No further quality improvements possible • Very limited application in virgin compounds
Introduction Devulcanization versus reclamation Crosslink scission properties of devulcanisatesimilartoproperties of originalmaterial DEVULCANIZATION: x Polymer scission shorter polymer chains poor properties REGENERATION:
Devulcanization Analytics – Horikx plot DEVULCANIZATION: sol + gel REGENERATION: sol M. M. Horikx, J. Polym. Sci. 19, 445 (1956)
Analytics – Horikx plot Hurdles to be taken • The original Horikx calculations are based on polymer networks without fillers Adjustments for the presence of fillers are necessary • Filler-polymer networks are not taken into consideration • Changes from polymer to crosslink scission in Horikx plot do not necessarily show linear correlation with distance from lines • Additional analytical methods are necessary M. M. Horikx, J. Polym. Sci. 19, 445 (1956)
Analytical methods White rubber test • Blending of 5% re-plasticized rubber with a bright white compound • Shade of grey devulcanized part of the material • Particles non-devulcanized cores of the particles or filler clusters 5% completely re-plasticized rubber Reference samples White rubber compound 10% ground rubber Samples with 5% devulcanizate
White rubber test Quantification Extruder-devulcanized samples Residence time: 6 min. Extruder-devulcanized samples Residence time: 6 min. Milled
(Passenger car) tire rubber Hurdles to be taken With courtesy from Apollo Global R&D • Blend of different types and brands of tires • Blend of different polymers and tire parts • Contamination with sand, … • Removal of reinforcing textile fibers • Residual activity of curatives • Reduced reinforcing strength of fillers
(Passenger car) tire rubber Hurdles to be taken With courtesy from Apollo Global R&D • Blend of different polymers and tire parts
SBR: Thermo-mechanical treatment Hurdles taken DE-VULCANIZATION OF TIRE RUBBERS Thermal treatment in presence of oxygen recombination S. Saiwari: Post-consumer tires back into new tires; thesis; UniversityTwente, 2013
Passenger car tire elastomers Devulcanization mechanisms DE-VULCANIZATION OF TIRE RUBBERS Devulcanization aid: DPDS, 15 mmol/100 g Oil: TDAE, 5%wt Temperature: 220C Time: 6 minutes Atmosphere: N2 purging Cooling: Liquid nitrogen SBR BR NR CIIR
Passenger car tire elastomers: fillers Silica-silane filler systems 100% ‘devulcanizate’ • Low devulcanization efficiency due to stable filler-polymer network (short bonds) • New formation of filler-polymer network required • Blendabilitywith virgin compound • Degree of devulcanization ↔ stress-strain properties?
Passenger car tire rubber Selected compounds: tread DE-VULCANIZATION OF TIRE RUBBERS Stress-strain properties of devulcanizate closer to original material!
A look into the future Trigger: temperature, radiation, chemicals … Material design for recycling: New curing systems Crosslink scission ‘on demand’ Reversible covalent filler-polymer bonds Resins Interpenetrating networks New additives Low molecular weight rubbers Modified polymers https://www.google.nl/search?biw=1455&bih=712&tbm=isch&sa=1&ei=I_PiWtnAKpHFwQLTqrXQDQ&q=modified+sbr+silica+&oq=modified+sbr+silica+&gs_l=psy-ab.3...267066.270785.0.271006.20.18.0.2.2.0.150.1797.8j10.18.0....0...1c.1.64.psy-ab..0.11.1142...0j0i67k1j0i30k1j0i8i30k1.0.U-qWsn1M2f4#imgrc=AElJUwbNH8JRFM:
Summary Progress • Whole truck tire rubber: upscaling with special extruder technology (TRL7-8) • Whole passenger car tire material prototype extruder process is operational (5-6) • but…. Hurdles • Passenger car tire rubber • - Devulcanizate is not smooth • breaking filler clusters • devulcanization of silica-polymer network • - Different types of networks • Shifting balance to crosslink scission and away from polymer breakdown • - Different types of compounds • Separation of different parts of tires by e.g. waterjet • - Different types of tires • Preference: Truck tires > passenger car tires, non-silica > passenger • car tires, silica
Acknowledgements Thank you for your attention Questions?