Devulcanization and Recycling of Waste Automotive Epdm Rubber Powder by Using Shearing Action and Chemical Additive

In automotive applications, ethylene-propylene-diene rubber (EPDM) is used to manufacture various components and therefore recycling scrap rubber is a major issue. The primary aim of this study was to develop a new method for devulcanizing waste automotive EPDM rubber powder by using shearing action and chemical additive and recycle the devulcanized powder. A semi-industrial twin screw extruder with a shearing action and reactor along with 2-mercaptobenzothiazole-disulfide (MBTS) chemical were used to devulcanize the waste powder at two different feed screw speeds and main rotor speeds at a constant temperature of 220°C. To recycle the devulcanized powder, different amounts of the devulcanized powder were mixed with a commercial EPDM-based automotive rubber strips compound to produce blends. The blends, commercial compound and devulcanized powder were cured with a semi-efficient (SEV) vulcanization system and their viscosity, cure and mechanical properties measured. For the blends, the Mooney viscosity was unchanged with 40 wt%, crosslink density with 20 wt%, tensile strength and elongation at break with 10 wt%, and compression set with 20 wt% of the devulcanized powder. Interestingly, the hardness benefitted from 50 wt% of the devulcanized powder in the blends. The scorch and optimum cure times shortened and the cure rate index rose when the loading of the devulcanized powder in the blends was raised. This new method offered a major new route for devulcanizing and recycling the waste powder.

[1]  H. Azizi,et al.  Continuous devulcanization of waste tires by using a Co‐rotating twin screw extruder: Effects of screw configuration, temperature profile, and devulcanization agent concentration , 2013 .

[2]  A. Bhowmick,et al.  Recycling of EPDM waste. I. Effect of ground EPDM vulcanizate on properties of EPDM rubber , 2001 .

[3]  Tianju Chen,et al.  Effects of high shear stress on the devulcanization of ground tire rubber in a twin-screw extruder , 2013 .

[4]  Meng-jiao Wang,et al.  Filler-Elastomer Interactions. Part VII. Study on Bound Rubber , 1993 .

[5]  Jin Kuk Kim,et al.  The biological and chemical desulfurization of crumb rubber for the rubber compounding , 1999 .

[6]  S. Tantayanon,et al.  Enhanced toughening of poly(propylene) with reclaimed‐tire rubber , 2004 .

[7]  A. Bhowmick,et al.  Morphology, mechanical and thermal behavior of acrylate rubber/fluorocarbon elastomer/polyacrylate blends , 2002 .

[8]  G. Gallone,et al.  Microwave‐induced devulcanization for poly(ethylene–propylene–diene) recycling , 2011 .

[9]  L. Janssen,et al.  EPDM Rubber Reclaim from Devulcanized EPDM , 2006 .

[10]  G. G. Stokes.  "J." , 1890, The New Yale Book of Quotations.

[11]  A. Isayev,et al.  Superior Mechanical Properties of Ultrasonically Recycled EPDM Rubber , 2003 .

[12]  Martin Bellander,et al.  Properties of Rubber Materials Containing Recycled Microbially Devulcanized Cryo-Ground Tire Rubber , 2001 .

[13]  M. Gradwell,et al.  The thermal decomposition of sulfenamide accelerators , 1994 .

[14]  D. De,et al.  Reclaiming of ground rubber tire by a novel reclaiming agent. I. virgin natural rubber/reclaimed GRT vulcanizates , 2007 .

[15]  V. Yashin,et al.  Ultrasonic devulcanization of carbon black–filled ethylene propylene diene monomer rubber , 2004 .

[16]  J. Oh,et al.  Continuous ultrasonic process for in situ compatibilization of polypropylene/natural rubber blends , 2003 .

[17]  J. Noordermeer,et al.  Mechanisms involved in the recycling of NR and EPDM , 1998 .

[18]  W. C. Warner.  Methods of Devulcanization , 1994 .

[19]  Subhas Chandra Debnath,et al.  Reclaiming of ground rubber tire (GRT) by a novel reclaiming agent , 2006 .

[20]  Leon P.B.M. Janssen,et al.  Modelling a continuous devulcanization in an extruder , 2006 .

[21]  L. Janssen,et al.  Modeling on the kinetics of an EPDM devulcanization in an internal batch mixer using an amine as the devulcanizing agent , 2006 .

[22]  Yanping Xia,et al.  The effect of devulcanization level on mechanical properties of reclaimed rubber by thermal‐mechanical shearing devulcanization , 2013 .

[23]  A. Isayev,et al.  Recycling of roofing membrane rubber by ultrasonic devulcanization , 2003 .

[24]  C. Han,et al.  Evolution of polymer blend morphology during compounding in a twin-screw extruder , 2000 .

[25]  F. P. Baldwin,et al.  Polyolefin Elastomers Based on Ethylene and Propylene , 1972 .

[26]  K. E. Polmanteer,et al.  Reinforcement Studies—Effect of Silica Structure on Properties and Crosslink Density , 1975 .

[27]  Tsu-Wei Chou,et al.  Microwave processing: fundamentals and applications , 1999 .

[28]  W. Dierkes,et al.  Rubber Recycling: Chemistry, Processing, and Applications , 2012 .

[29]  A. J. Zattera,et al.  Devulcanization of ethylene‐propylene‐diene polymer residues by microwave—Influence of the presence of paraffinic oil , 2011 .

[30]  Peter C. Jurs,et al.  Chemistry: The Molecular Science , 2001 .