Reclaimed rockwool fibers for thermally stable palm oil-based polyurethane foam

Abstract

Due to its non-existent recyclability, industrial rockwool fiber wastes have caused environmental and waste management issues, which, therefore, necessitates an effective and sustainable solution. In this paper, palm oil-based polyurethane (PU) foam is synthesized, incorporating reclaimed rockwool fibers from discarded industrial insulation system as fillers. The filler loadings were varied from 1 wt.% to 10 wt.%, and fabricated foams were then characterized for their fire retardancy, thermal stability, foam morphology, and mechanical responses. Thermal stability of the foam was significantly improved with inclusion of rockwool fibers as evidenced by marked delay in 50% degradation temperature, T-50, as well as char residue yield in thermogravimetry analysis (TGA). In contrast, no noticeable change was detected for its flammability. Both cell sizes and open cell contents increased with filler content, probably due to the filler inducing delayed blowing reaction. Increasing rockwool fiber contents showed limited improvement in compressive properties, which is thought owed to restricted polymer-filler interfacial area for efficient load transfer. This novel composite foam shows potential for application requiring moderate thermal stability and load-bearing capabilities.