Next-generation Recycling of High-density Fibreboard: Controlled Fibre Recovery Using Thermo-hydro-microwave Synergy

Abstract

This study investigated a next-generation recycling strategy for high-density fibreboard (HDF) based on controlled fibre recovery using thermo–hydro–microwave (THM) synergy. Industrial HDF boards with a target density of 900 kg/m³ were treated in saturated steam at 110 °C and 0.2 MPa for 30 min, followed by two microwave treatment cycles of 30 s each at 800 W. The treated material was subsequently disintegrated in hot water (80 °C), and the recovered wood fibres were separated, dewatered, and dried. The recycled fibres were used to manufacture single-layer and three-layer laboratory-scale HDF panels with different recycled fibre contents. The panels were evaluated for selected mechanical and physical properties, including bending performance, internal bond strength, dimensional stability, surface water absorption, and density profile. The results confirmed that the applied THM-assisted recycling process enabled effective fibre recovery while limiting excessive fibre shortening. Three-layer HDF panels containing 40 to 50% recycled fibres exhibited properties comparable to or exceeding those of reference panels. The findings demonstrate the potential of thermo–hydro–microwave-assisted recycling as a viable approach for closed-loop HDF production and improved material circularity.