Fabrication and investigation of a novel composite based on waste polyurethane rigid foam and wood veneer

The escalating demand for polyurethane rigid foams (PURF) has resulted in a substantial increase in waste polyurethane products. In view of the difficulty in recycling waste PURF, this study introduces a novel mechanical recycling process that is cost-effective and features a straightforward fabrication process for producing PUW (waste PURF combined with wood veneers), which solves the problem of low strength products obtained from mechanical recycling of PU waste. Through investigation of the PURF (ground into particles before using) particle size, core layer density, the amount of resin and thickness, the optimal fabrication process was confirmed as follows: particles with the size of 1 to 3 mm as its core layer components, 0.9 g/cm3 as its core layer density, the addition of MDI to be 20 wt%, and 8 mm thickness of whole composite. The resulting PURF-based composite exhibited superior thermal insulation properties, mechanical strength, and sound insulation performance. The optimized PUW composite had a notably low thermal conductivity of 0.04126 W/(m·K), slightly higher than that of rock wool board (0.04 W/(m·K)). In terms of mechanical performance, the wet shear strength of the optimal PUW composite reached 0.61 MPa. Furthermore, the PUW composite exhibited relatively high sound insulation, particularly at high frequencies.