Devulcanization of ground tire rubber: Physical and chemical changes after different microwave exposure times

Microwave devulcanization is known to be a promising and an efficient rubber recycling method which makes possible for the rubber to regain its fluidity, and makes it capable of being remolded and revulcanized. The focus of this work is to understand the physical and chemical changes that occur in the ground tire rubber after different microwave exposure periods. For this purpose chemical, thermal, rheological and morphological analyses were performed on the tire rubber, which contains natural rubber (NR) and styrene-butadiene rubber (SBR) as polymeric material. The results showed that the microwave treatment promoted the breaking of sulfur cross-links and consequently increased the rubber fluidity. However, long periods of exposure led to degradation and modification of some properties. At nanoscale, the deformation of the devulcanized NR domain under stress was observed, and the morphology obtained appears to be a droplet dispersion morphology. The most exposed samples presented only one glass transition temperature, and from this it was concluded that the treatment may have played an important role in the compatibilization of the elastomeric blend. Based on the results, it is required to control the microwave exposure time and polymeric degradation in order to achieve a regenerated rubber with satisfactory properties.

[1]  A. J. Zattera,et al.  Degradation kinetics of ethylene propylene diene terpolymer residues devulcanized by microwaves , 2014 .

[2]  F. Lagarde,et al.  Raman spectroscopy and thermal analysis of gum and silica-filled NR/SBR blends prepared from latex system , 2013 .

[3]  Dimitrios N. Bikiaris,et al.  Characterization and thermal degradation mechanism of isotactic polypropylene/carbon black nanocomposites , 2007 .

[4]  Rakshit Ameta,et al.  An Overview of Rubber Recycling , 2008 .

[5]  E. Hegazy,et al.  Thermo-mechanical properties of devulcanized rubber/high crystalline polypropylene blends modified by ionizing radiation , 2013 .

[6]  R. E. S. Bretas,et al.  Blends of PS with SBR Devulcanized by Ultrasound: Rheology and Morphology , 2004 .

[7]  G. Mckay,et al.  Kinetic Modeling of Waste Tire Carbonization , 2008 .

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

[9]  C. Roy,et al.  Improved Quantitative Determination of Elastomers in Tire Rubber by Kinetic Simulation of DTG Curves , 1993 .

[10]  M. D. da Silva,et al.  Thermal analysis of ground tire rubber devulcanized by microwaves , 2007 .

[11]  M. Narkis,et al.  Dielectric behavior of carbon black filled polymer composites , 1986 .

[12]  S. Gunasekaran,et al.  FTIR spectra and mechanical strength analysis of some selected rubber derivatives. , 2007, Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy.

[13]  J. Karger‐Kocsis,et al.  Ground tyre rubber (GTR) in thermoplastics, thermosets, and rubbers , 2012, Journal of Materials Science.

[14]  Pamela Sierra Garcia,et al.  Effect of residual contaminants and of different types of extrusion processes on the rheological properties of the post-consumer polypropylene , 2013 .

[15]  Xinxing Zhang,et al.  Properties of natural rubber vulcanizates containing mechanochemically devulcanized ground tire rubber , 2009 .

[16]  A. Bantjes,et al.  A scanning force microscopy study on the morphology of elastomer-coagent blends , 1993 .

[17]  A. Isayev,et al.  Nonisothermal Vulcanization of Devulcanized GRT with Reversion Type Behavior , 2006 .

[18]  A. Isayev.  Recycling of Rubbers , 2005 .

[19]  R. O. Aly,et al.  Mechanochemical devulcanization and gamma irradiation of devulcanized waste rubber/high density polyethylene thermoplastic elastomer , 2013 .

[20]  G. Jiang,et al.  Microbial desulfurization of SBR ground rubber by Sphingomonas sp. and its utilization as filler in NR compounds , 2011 .

[22]  F. D. Sousa,et al.  The Use of Atomic Force Microscopy as an Important Technique to Analyze the Dispersion of Nanometric Fillers and Morphology in Nanocomposites and Polymer Blends Based on Elastomers , 2014 .

[23]  M. Giovanela,et al.  Use of styrene butadiene rubber industrial waste devulcanized by microwave in rubber composites for automotive application , 2012 .

[24]  Jin Kuk Kim,et al.  Processing and characterization of microwave and ultrasonically treated waste-EPDM/LDPE polymer composites , 2015 .

[25]  A. Isayev,et al.  Ultrasound Devulcanization of Sulfur Vulcanized SBR: Crosslink Density and Molecular Mobility , 1996 .

[26]  H. Radusch,et al.  Filler Phase Distribution in Rubber Blends Characterized by Thermogravimetric Analysis of the Rubber-Filler Gel , 2008 .

[27]  R. Farris,et al.  A novel approach to improving the mechanical properties in recycled Vulcanized natural rubber and its mechanism , 2002 .

[28]  Vinicius Pistor,et al.  Desvulcanização do resíduo de terpolímero de etileno-propileno-dieno (EPDM-r) por micro-ondas , 2010 .

[29]  R. Jeng,et al.  Carbon black-containing interpenetrating polymer networks based on unsaturated polyester/epoxyII. Thermal degradation behavior and kinetic analysis , 2002 .

[30]  S. Ghose,et al.  Effects of ultrasonic treatment on unfilled butadiene rubber , 2003 .

[31]  Agurtzane Mugica,et al.  Pyrolysis-FTIR and TGA techniques as tools in the characterization of blends of natural rubber and SBR , 2006 .

[32]  Marina Lasagni,et al.  Characterization and supercritical CO2 devulcanization of cryo-ground tire rubber: Influence of devulcanization process on reclaimed material , 2014 .

[33]  Joonmo Ahn,et al.  Microwave absorbing properties of carbon black/silicone rubber blend , 2002 .

[34]  G. Heinrich,et al.  Dispersion and distribution of carbon nanotubes in ternary rubber blends , 2014 .

[35]  I. H. Jeon,et al.  Characterization of rubber micro-morphology by atomic force microscopy(AFM) , 2003 .

[36]  Frédérique Guillamot,et al.  Influence of interface energy on compatibility between ground tyre rubber and bitumen used in asphalt pavement , 2013 .

[37]  R. E. S. Bretas,et al.  Caracterização térmica e reológica de borracha de pneu desvulcanizada por microondas , 2006 .

[38]  B. Adhikari,et al.  Reclamation and recycling of waste rubber , 2000 .

[39]  C. Saron,et al.  Chemical Modifications in Styrene–Butadiene Rubber after Microwave Devulcanization , 2012 .

[40]  Davide Lo Presti,et al.  Definition of a laboratory optimization protocol for road bitumen improved with recycled tire rubber , 2012 .