Thermochimica Acta 444 (2006) 65–70 Pyrolysis-FTIR and TGA techniques as tools in the characterization of blends of natural rubber and SBR Mar´ ıa Jos´ e Fern´ andez-Berridi ∗ , Nekane Gonz´ alez, Agurtzane Mugica, Caroline Bernicot Department of Science and Technology of Polymers and Institute of Polymer Materials (POLYMAT), Faculty of Chemistry, University of the Basque Country, P.O. Box 1072, 20080 San Sebasti´ an, Spain Received 19 October 2005; received in revised form 21 February 2006; accepted 23 February 2006 Abstract The employment of used tyres as a new source of raw materials for different applications can be a partial solution to the great environmental problems generated by these products concerning their disposal at waste depots. In this study, high-resolution thermogravimetric analysis (Hi-Res TGA) is used to quantify the elastomer composition of SBR/NR in tyre formulations. This technique provides the ability to generate TGA derivative profiles (DTGA), which can be used to distinguish different formulations from appropriate calibration curves. Infrared spectroscopy (FTIR) is also employed for composition quantification of used tyres and the results are compared to those obtained by Hi-Res TGA. Both analysis methods give satisfactory results when applied to elastomer mixtures of known composition and to tyre rubbers of unknown composition. The study confirms the accuracy of high-resolution TGA–DTGA technique for rapid quantitative determination of elastomer blends in used tyres. © 2006 Elsevier B.V. All rights reserved. Keywords: Used tyres; Elastomers; Hi-Res TGA; FTIR 1. Introduction Tyre recycling or reprocessing are one of the preferable pro- cesses, according to the so-called waste management hierarchy, under environmental aspects. The re-use of tyres in alternative applications is one example of this, as the basis polymer can be reused in new formulations with the consequent cost saving in raw material, and preserving both natural resources and environ- ment. In addition to the reincorporation of the elastomer in new formulations, a controlled pyrolysis of vulcanized elastomers allows the recover of oil and carbon black, which in turn can be reused. A piece of rubber for tyres is basically a mixture of two or more polymers, carbon black, inorganic compounds (calcium carbonate, silica, etc.) and a relatively high number of organic substances as plasticizers, lubricants, antioxidants, vulcaniza- tion agents and so on, that are considered to be dissolved in the polymer matrix. The formulation breakdown and the identifica- ∗ Corresponding author. Tel.: +34 943018194; fax: +34 943015270. E-mail address: mj.fernandezberridi@ehu.es (M.J. Fern´ andez-Berridi). tion and quantification of each of its components are a laborious task, which has been done by different, time consuming tech- niques. A standard tyre formulation for trucks as well as cars is that which incorporates as basis polymer a physical blend of nat- ural rubber (NR) with a styrene/butadiene containing elastomer (SBR) in adequate proportions for a specific application. The physical and mechanical properties of blends of SBR, NBR and NR are sensitive to small variations in the amounts of individual polymers used. Therefore, it is necessary to develop a variety of analytical tools to monitor blend compositions. Ther- mogravimetric analysis [1–9] and pyrolysis-GC/MS [10,11] have been employed extensively to study the feasibility of char- acterizing NR/SBR and BR/NR blends. TGA is one of the most employed techniques in these cases due to its rapidity and to a lesser necessity of sample manipulation compared with other methods in conventional analysis. Specifically, differen- tial thermal gravimetric analysis (DTGA) has a considerable value for estimating the basic composition of vulcanizates [3–8]. Elastomer DTGA curves are used as “fingerprints” in the iden- tification of many single elastomers and blends, finding that the peak height of the derivatives TGA (DTGA), is depen- dent on the amount of each elastomer in the sample. Therefore, 0040-6031/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.tca.2006.02.027