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Materials 2016, 9(9), 724; doi:10.3390/ma9090724

Upscaling of a Batch De-Vulcanization Process for Ground Car Tire Rubber to a Continuous Process in a Twin Screw Extruder

Elastomer Technology and Engineering (ETE), Department of Solids, Surfaces and Systems (MS3), University of Twente, Enschede 7522 NB, The Netherlands
Polymer Engineering, University of Applied Sciences Windesheim, Zwolle 8017 CA, The Netherlands
Author to whom correspondence should be addressed.
Academic Editor: Dariusz M. Bieliński
Received: 28 June 2016 / Revised: 1 August 2016 / Accepted: 17 August 2016 / Published: 24 August 2016
(This article belongs to the Special Issue Advances in Research on Elastomers)
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As a means to decrease the amount of waste tires and to re-use tire rubber for new tires, devulcanization of ground passenger car tires is a promising process. Being an established process for NR and EPDM, earlier work has shown that for ground passenger car tire rubber with a relatively high amount of SBR, a devulcanization process can be formulated, as well. This was proven for a laboratory-scale batch process in an internal mixer, using diphenyl disulfide as the devulcanization aid and powder-sized material. In this paper, the devulcanization process for passenger car tire rubber is upscaled from 15 g per batch and transformed into a continuous process in a co-rotating twin screw extruder with a capacity of 2 kg/h. As SBR is rather sensitive to devulcanization process conditions, such as thermal and mechanical energy input, the screw design was based on a low shear concept. A granulate with particle sizes from 1–3.5 mm was chosen for purity, as well as economic reasons. The devulcanization process conditions were fine-tuned in terms of: devulcanization conditions (time/temperature profile, concentration of devulcanization aid), extruder parameters (screw configuration, screw speed, fill factor) and ancillary equipment (pre-treatment, extrudate handling). The influence of these parameters on the devulcanization efficiency and the quality of the final product will be discussed. The ratio of random to crosslink scission as determined by a Horikx plot was taken for the evaluation of the process and material. A best practice for continuous devulcanization will be given. View Full-Text
Keywords: devulcanization; tire; twin-screw extruder; DPDS; low shear; thermo chemical; Horikx devulcanization; tire; twin-screw extruder; DPDS; low shear; thermo chemical; Horikx

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

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Saiwari, S.; van Hoek, J.W.; Dierkes, W.K.; Reuvekamp, L.E.; Heideman, G.; Blume, A.; Noordermeer, J.W. Upscaling of a Batch De-Vulcanization Process for Ground Car Tire Rubber to a Continuous Process in a Twin Screw Extruder. Materials 2016, 9, 724.

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