11 PROGRESS AND HURDLES IN TIRE RECYCLING Wilma

11 PROGRESS AND HURDLES IN TIRE RECYCLING Wilma Dierkes University of Twente Enschede the Netherlands H. van Hoek S. Saiwari J. Noordermeer A. Blume

Y AR ED TS EN T GE M EN PM LO VE DE OW L CK N &A RE FU TU BE R ER UB MS TE YS RS TIR LE RC AR GE EN SS PA MM SU LE WH O FIL ER S OM SIS ST LA TIR EE AL Y AN S N IO IVE ER NA T AL T AR RC GE EN SS PA RE CY CL ING UC T RO D INT 22 PROGRESS AND HURDLES IN TIRE RECYCLING OUTLOOK

3 Introduction Trends in tires & sustainability EU USA Korea Japan https: //media. licdn. com/mpr/AAEAAQAAAAf. BAAAAJGRi. MDc 3 YTc 5 LWMz. OTQt. NDEw. ZS 05 Zjgw. LWZi. MWFl. Mz. Qw. Zj. Rl. NA. jpg Publication date R&D: Number of patents on… http: //www. tirereview. com/wp-content/uploads/Articles/02_01_2013/109978 febcovera_00000060668. jpg http: //www. hankooktire. com/global/tires-services/technology/tire-labeling/overview/_jcr_content/par/image_0. img. jpg/1424738449507. jpg China

4 Introduction Recycling alternatives Cradle to Cradle G IN D IN R G E FIN DEVULCANIZATION PYR OLY or o SIS ther proc esse s Cradle to cradle via … http: //wdo. ca/Portals/_default/Skins/wdo/sliderimg/ usedtires. jpg http: //tyrepyrolysisplants. net/wp-content/uploads/2015/04/usedtirespyrolysis. jpg

5 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 Pyrolysis Grinding Ø Technology Readiness Levels (TRL): - Passenger car tire rubber: TRL 5 -6 (technology demonstration) - Truck tire rubber: TRL 7 -8 (system development) Ø Concentration of devulcanizate in tire compounds: a multitude of current concentrations (depending on the compound type) Ø Technology Readiness Levels (TRL): - No significant development potential of conventional technologies (batch, long residence time, high temperatures) - Improvements by after-treatments - New technologies! Ø Large-scale application in tires only possible with significant quality improvements Ø Technology available, also for very fine powder Ø No further quality improvements possible Ø Very limited application in virgin compounds 6

7 Introduction Devulcanization versus reclamation DEVULCANIZATION: REGENERATION: Crosslink scission properties of devulcanisate similar to properties of original material Polymer scission shorter polymer chains poor properties x

8 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 Ø The original Horikx calculations are based on polymer networks without fillers Adjustments for the presence of fillers are necessary Ø Filler-polymer networks are not taken into consideration Ø Changes from polymer to crosslink scission in Horikx plot do not necessarily show linear correlation with distance from lines Ø Additional analytical methods are necessary M. M. Horikx, J. Polym. Sci. 19, 445 (1956) 9

10 Analytical methods White rubber test Ø Blending of 5% re-plasticized rubber with a bright white compound Ø Shade of grey devulcanized part of the material Ø Particles non-devulcanized cores of the particles or filler clusters Reference samples White rubber compound 10% ground rubber Samples with 5% devulcanizate 5% completely re-plasticized rubber

11 White rubber test Quantification Extruder-devulcanized samples Residence time: 6 min. Milled

12 (Passenger car) tire rubber Hurdles to be taken Component With courtesy from Apollo Global R&D Polymers Tread SBR, BR Belt NR Sidewall NR, BR Carcass SBR, NR, BR Bead NR Apex SBR, NR, BR Cap-ply NR, BR Inner liner SBR, NR, IIR Ø Blend of different types and brands of tires Ø Blend of different polymers and tire parts Ø Contamination with sand, … Ø Removal of reinforcing textile fibers Ø Residual activity of curatives Ø Reduced reinforcing strength of fillers

13 (Passenger car) tire rubber Hurdles to be taken Component With courtesy from Apollo Global R&D Polymers Tread SBR, BR Belt NR Sidewall NR, BR Carcass SBR, NR, BR Bead NR Apex SBR, NR, BR Cap-ply NR, BR Inner liner SBR, NR, IIR Ø Blend of different polymers and tire parts

SBR: Thermo-mechanical treatment DE-VULCANIZATION OF TIRE RUBBERS Hurdles taken Thermal treatment in presence of oxygen recombination S. Saiwari: Post-consumer tires back into new tires; thesis; University Twente, 2013 14

15 Passenger car tire elastomers DE-VULCANIZATION OF TIRE RUBBERS Devulcanization mechanisms Devulcanization aid: DPDS, 15 mmol/100 g Oil: TDAE, 5%wt Temperature: 220 C Time: 6 minutes Atmosphere: N 2 purging Cooling: Liquid nitrogen SBR BR NR CIIR

Passenger car tire elastomers: fillers Silica-silane filler systems 100% ‘devulcanizate’ Ø Low devulcanization efficiency due to stable filler-polymer network (short bonds) Ø New formation of filler-polymer network required Ø Blendability with virgin compound Ø Degree of devulcanization ↔ stress-strain properties? 16

Passenger car tire rubber DE-VULCANIZATION OF TIRE RUBBERS Selected compounds: tread Stress-strain properties of devulcanizate closer to original material! 17

18 A look into the future Material design for recycling: New curing systems Crosslink scission ‘on demand’ Reversible covalent fillerpolymer bonds Trigger: temperature, radiation, chemicals … Resins New additives Low molecular weight rubbers Modified polymers https: //www. google. nl/search? biw=1455&bih=712&tbm=isch&sa=1&ei=I_Pi. Wtn. AKp. HFw. QLTqr. XQDQ&q=modified+sbr+silica+&oq=modified+sbr+silica+&gs_l=psyab. 3. . . 267066. 270785. 0. 271006. 20. 18. 0. 2. 2. 0. 150. 1797. 8 j 10. 18. 0. . . 1 c. 1. 64. psy-ab. . 0. 1142. . . 0 j 0 i 67 k 1 j 0 i 30 k 1 j 0 i 8 i 30 k 1. 0. U-q. Wsn 1 M 2 f 4#imgrc=AEl. JUwb. NH 8 JRFM: Interpenetrating networks

Summary 19 Progress § Whole truck tire rubber: upscaling with special extruder technology (TRL 7 -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

20 Acknowledgements Thank you for your attention Questions ?