Investigation of volatile low molecular weight compounds formed during continuous reclaiming of ground tire rubber

Ground tire rubber was thermo-mechanically reclaimed at different temperature conditions (80, 120, 160 degrees C) using a co-rotating twin screw extruder. The progress of ground tire rubber reclaiming was evaluated with specific mechanical energy, sol fraction and thermogravimetric analysis. Volatile organic compounds (VOCs) including volatile sulfur compounds (VCSs) released from ground tire rubber and ground tire rubber after reclaiming were investigated. The quality of VOCs was studied using dynamic headspace and gas chromatography-mass spectrometry (DHS-GC-MS). Total amount of VOCs was evaluated with static headspace and gas chromatography with flame ionization detector (SHS-GC-FID). Analysis of volatile sulfur compounds was performed using a static headspace and gas chromatography with flame photometric detector (SHS-GC-FPD). Studies of total VOCs content by SHS-GC-FID revealed that, depending on sample, the determined concentration in the headspace phase at 150 degrees C varied in the range of 17.5-31.4 mu g/ml. A large number of individual VOCs, including BTEX compounds, ketones and aldehydes as well as volatile sulfur compounds (VSCs), has been identified by DHS-GC-MS technique. In the VSCs group hydrogen sulfide, benzothiazole, 3-methylthiophene, 2-methylthiophene were determined. Benzothiazole was the most abundant sulfur compound due to degradation of vulcanization accelerators residue present in GTR. The highest concentration of VOCs was found for sample processed at the highest temperature 160 degrees C. The study revealed that, during extrusion, degradation products interacted with each other and formed new chemical structures which affected the total amount of volatile organic compounds. (C) 2015 Elsevier Ltd. All rights reserved.