New applications for foam composites of polyurethane and recycled rubber

In Portugal, most end-of-life tires are recycled through a process involving a cryogenic grinding technology. The purpose of this work was to envisage new applications for recycling rubber from end-of-life tires. In this work, rubber was supported in a polyurethane matrix generating two new products of distinct characteristics and properties. The choice of these products was ruled by the requests of potential clients: (a) Floating trays to withstand the load of plants capable of cleansing polluted water from lagoons, ponds, or basins; (b) Compression-absorbing buoys to dampen the shocks and the compressive stresses between ships and docks. The polyurethane formulations developed herein were based on methylene diphenyl diisocyanate and a trifunctional polyol such that the final foam would be flexible. As the floating trays' density should be lower than the water density, the best formulation found comprised 150% of rubber, 4% of water (relative to the polyol mass), with an isocyanate index of 105% and a density of 89 kg m-3. The foam that presented the optimal compression behavior to be applied in compression absorbing buoys, comprised 200% of rubber, 3% of water, with an isocyanate index of 105% and a density of 121 kg m-3. In both cases, the composite foam materials obtained showed final properties compatible with the envisaged applications, pointing out that the implied methodology may be used in the future to recycle rubber from end-of-life tires. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013