Formulation and characterization of leather and rubber wastes composites

Abstract

Residues from footwear roughing and carding operations represent 515% (w/w) of the solid wastes generated by shoe-making companies. These wastes are mainly composed by chromium tanned leather and sole materials, and are mostly land filled. Sometimes leaching tests show these wastes as hazardous due to chromium in the leachate. This work aims at a more sustainable option for these wastes by recycling them in styrene butadiene rubber (SBR) and acrylonitrile butadiene rubber (NBR). Thus, they were charged with: (i) 1 mm leather waste fibers in the range of 1025 parts per hundred parts of rubber (phr); and (ii) leather and soles industrial carding and roughing wastes in the range of 20100 phr. The leather waste fibers-rubber composites tear strength is increased till 25 phr and both tension and elongation at break decrease within the acceptable range till 12.5 phr for SBR and 15 phr for NBR. In the case of leather and sole carding and roughing wastes, composites tear strength increases till 100 phr, and tension and elongation decrease within the acceptable range till 20 phr. The composite materials at the end of their life cycle may be considered inert or non-hazardous wastes.