Recycling Waste Tires: Generation of Functional Oligomers and Description of Their Use in the Synthesis of Polyurethane Foams

The accumulation of waste tires is a big environmental issue and different approaches have been proposed to eliminate or recycle this material in the end of its life. However, each approach presents drawbacks and the need for a real valorization of the tire components is still of interest. In a previous work by our group, it was demonstrated that an oxidative cleavage of the polyisoprene and polybutadiene chains contained in the tires led to the synthesis of telechelic oligomers with a ketone and an aldehyde at the chains ends. In this work, the process to obtain these carbonyl oligomers has been improved, with a particular concern for the elimination of the maximum amount of carbon black. The carbonyl oligomers can be easily reduced to hydroxyl oligomers and, in order to show the benefit of the recycling process, an application of these hydroxyl oligomers is reported: they have been used as building blocks (polyol precursors) in the preparation of polyurethane (PU) foams. The morphology of the resulting foams was observed by scanning electron microscopy technique: the images showed an almost open-cell structure and a homogeneous distribution of cell size. Mechanical (tensile and compressive strength) and thermal properties of PU foams synthesized from "recycled" oligomers from waste tires were compared to those of PU foams synthesized from analogue oligomers derived from natural rubber. (C) 2014 Wiley Periodicals, Inc.