Properties of Fiberboards Bonded by Decomposed Polyurethane Foams and Isocyanate

The objective of this study was to investigate the feasibility of using recycled polyols as part of the binder system for wood panels (fiberboard). PU foam wastes from disposed insulation materials were collected, processed, and chemically decomposed by agent to obtain the recycled polyol. The recycled polyol was mixed with a commercial polyol at various weight ratios (0: 100, 20: 80, 40: 60, 60: 40, 80: 20, and 100: 0) to prepare a series of polyol mixtures. Then, the obtained polyol mixtures were then sprayed successively with pMDI resin at various pMDI/polyol mixtures weight ratios (100: 0, 75: 25, and 50: 50) onto wood fibers to prepare fiberboards. The effects of recycled polyol/commercial polyol weight ratio and pMDI/polyol mixture weight ratio on physical and mechanical properties of bonded fiberboards were evaluated. The results showed that the addition of recycled polyol into a commercial polyol helped improve the IB, MOR, and MOE strength of fiberboard, but their effects on water resistance of fiberboard were minor. With the increase of percentage of polyol mixture in pMDI/polyol mixture, the properties of fiberboard presented a trend of decreasing. When the recycled polyol/commercial polyol weight ratio was 40: 60 and the pMDI/polyol mixture was 25: 75, the bonded fiberboard had the overall best physical and mechanical performances. The application of decomposed PU foams in fiberboard production provided a new possible way of recycling polymer wastes.