Characterization of recycled styrene butadiene rubber ground tire rubber: Combining X‐ray fluorescence, differential scanning calorimetry, and dynamical thermal analysis for quality control

Abstract

Appraisal of the main rubber characterization techniques for styrene butadiene rubber (SBR) was performed on standard SBR samples as well as recycled ground tire rubber (GTR) from an industrial tire recycling facility, containing a blend of SBR and natural rubber. The aim of the work was to provide additional information relevant to quality control in the field of rubber recycling. Benchmark characterization of industrial samples by inductively coupled plasma optical emission spectrometry, atomic absorption spectrometry, solid-state proton nuclear magnetic resonance, and elemental (CHNS) analysis are reported. X-ray fluorescence spectrometry is shown to be rapid and quantitative for determining the zinc content in an industrial context. Thermogravimetric analysis, already used to determine carbon black and inorganic material content in rubbers and GTR, is recommended for determination of monomer weight ratios of SBR sources not containing other rubbers, but not for GTR. Differential scanning calorimetry (DSC) measurements of the glass-transition show that changes in monomer ratio affect glass-transition temperature values, and therefore, DSC can be used to detect changes in rubber composition from batch to batch. These results show that DSC and X-ray fluorescence spectroscopy characterization techniques can be used for GTR and may lead to more thorough and rapid quality control procedures of these complex samples.

Synergistic Effects of Bitumen Plasticization and Microwave Treatment on Short-Term Devulcanization of Ground Tire Rubber

“…This non-destructive method allows rapid and quantitative determination of content of silicon (Si), sulfur (S), zinc (Zn), calcium (Ca), magnesium (Mg), aluminum (Al), and iron (Fe) in rubber compounds [27,28]. Miskolczi et al [29], and recently Liang et al [30], confirmed that the most intense signal from X-ray fluorescence spectrometry corresponds to zinc, and it is related to its high concentration in GTR. In the studied case the range is 1.22–2.33 wt %.…”

“…The measurements obtained by oscillating disc rheometer discussed later seem to confirm this statement. On the other hand, it should be pointed out that there is no simple correlation between sulfur content and cross-link density [30,32]. Higher sulfur content in the case of GTR samples modified with bitumen could also be explained by sulfur derivatives (such as hydrogen sulfide, carbon disulfide, etc.)…”

FTIR spectroscopic and thermogravimetric characterization of ground tyre rubber devulcanized by microwave treatment

“…After this period the oven door is opened with a gap of 3 cm to introduce oxygen gas for 30 minutes in order to achieve the total oxidation of the sample. The remaining ashes corresponds to the part of inorganic components of the GTR, basically SiO 2 , ZnO, and small quantities of Fe 2 O 3 and CaCO 3 [26]. To determine the ash content percentage the equation (4) Figure 1 shows particle size distribution of different GTR used in this study.…”

Rotomolding of Thermoplastic Elastomers Based on Low-Density Polyethylene and Recycled Natural Rubber

“…As expected, the presence of oxygen in air decreases the thermal stability of all materials. The highest decomposition temperature can be associated to the oxidation of carbon residues generated at lower temperatures, leading to the formation of carbon dioxide [25]. Liang et al [26] studied the existence of inorganic compounds like silicon, calcium, and zinc in the form of SiO 2 , ZnO, and CaCO 3 in GTR, individually.…”