Reinforcing mechanically reclaimed polyurethane foam wastes-based elastomer with modified recycled polyester fibers

Polyurethane foams are widely used in daily life due to their superior performance. However, it is very challenging to recycle and reuse waste polyurethane foams since the three-dimensional crosslinking network structure makes them non-melting and insoluble. In this work, a low-cost, green, room-temperature solid-state shear milling method is proposed to break the cross-linking bonds of waste polyurethane foam (crosslinking density decreases from 0.768 to 0.489 mol dm(-3)). The recycled polyurethane (RPU) powders regain their thermoplastic processability. Recycled waste polyester (PET) fibers are modified through plasma treatment and used as reinforcing fillers for the reprocessed RPU elastomer. Compared to original PET fibers, modified polyester (m-PET) fibers construct strong interfacial interactions and physical interlocks with RPU matrix, leading to significantly enhanced mechanical properties. Molecular dynamics studies demonstrate that RPU/m-PET composites have higher cohesive energy density and lower free volume, and significantly improved compatibility, which greatly promotes stress dissipation upon stretching. This study provides a feasible strategy for the high-value recycling of waste polymer materials.