Mechanical, thermal, and sorption behaviours of polyurethane rich footwear waste-clay reinforced natural rubber

Reusing industrial wastes is one of the cutting-edge tactics used to counteract solid waste disposal for environmental protection. The rigid polyurethane waste (PW) produced while manufacturing shoe soles in the footwear industry contributes to major environmental problems due to its uncontrolled landfill. In the current work, PW and clay were used as fillers in natural rubber (NR) and the fabricated compound’s mechanical, thermal, and sorption properties were looked at. Various analytical techniques were employed to characterise the NR-PW-clay compounds produced by the two-roll mill mixing process. In contrast to NR, the tensile strength and tear resistance of NR compound with 5 phr (parts per hundred rubber) PW and 10 phr clay was improved by 20% and 7%, respectively, and abrasion loss was significantly reduced. The mechanical characteristics of the compounds showed a decreasing trend beyond 10 phr clay due to the PW and clay particle’s aggregation. The thermal stability of NR-PW-clay compounds was slightly increased upon adding clay, as demonstrated by thermogravimetric analysis (TGA). As clay loading increased, the crosslink density and swelling index measurements revealed improved solvent absorption resistance. The fabricated compounds have the potential to provide high-performance, inexpensive NR compounds for a variety of industrial applications.