Properties of Medium-Density Fiberboards with Different Contents of Recycled Fibers and Urea-Formaldehyde Resin

Highlights What are the main findings? The complete replacement of virgin fibers with recycled fibers significantly reduces MDF panel performance, with declines in MOE, MOR, IB strength, and other key properties, making 100% substitution unsuitable for MDF production. The optimal recycled fiber content is up to 24%, with at least 12% UF resin to ensure mechanical integrity. Panels with up to 20% recycled fiber maintain acceptable properties, but performance declines sharply between 20% and 40%. Further research is needed for recycled fiber content between 40% and 60%. Increasing the UF resin content can help to counteract the negative effects of recycled fibers, with formaldehyde scavenging by amines allowing for higher resin content without significantly increasing formaldehyde emissions. What are the implications of these findings? The findings provide valuable insights for MDF manufacturers, helping to support more sustainable, cost-effective, and high-performance production. Future research should focus on improving the recycling process and exploring alternative resins to enhance sustainability and reduce the environmental footprint of MDF production.Highlights What are the main findings? The complete replacement of virgin fibers with recycled fibers significantly reduces MDF panel performance, with declines in MOE, MOR, IB strength, and other key properties, making 100% substitution unsuitable for MDF production. The optimal recycled fiber content is up to 24%, with at least 12% UF resin to ensure mechanical integrity. Panels with up to 20% recycled fiber maintain acceptable properties, but performance declines sharply between 20% and 40%. Further research is needed for recycled fiber content between 40% and 60%. Increasing the UF resin content can help to counteract the negative effects of recycled fibers, with formaldehyde scavenging by amines allowing for higher resin content without significantly increasing formaldehyde emissions. What are the implications of these findings? The findings provide valuable insights for MDF manufacturers, helping to support more sustainable, cost-effective, and high-performance production. Future research should focus on improving the recycling process and exploring alternative resins to enhance sustainability and reduce the environmental footprint of MDF production.Abstract Recycling wood-based panels is essential for promoting the cascading use of wood, advancing the transition to a circular economy, and maximizing the efficient use of natural resources. While recycling particleboard has become a well-established industrial practice, recycling medium density fiberboard (MDF) panels presents challenges, particularly in preserving material quality. The aim of this research work was to investigate and evaluate the combined effect of recycled MDF fibers and urea-formaldehyde (UF) resin content on the performance characteristics of the panels. MDF recycling was conducted using hydrothermal hydrolysis and hammer mill refinement. Preliminary experiments revealed that the degradation of properties in recycled MDF panels is not uniform with the addition of recycled fibers. The panels retained their properties significantly with up to 20% recycled fiber content, while formaldehyde emissions decreased by 1.2%. Based on these findings, the optimization of recycled fiber and UF resin content was performed, revealing that the maximum allowable recycled fiber content through hydrothermal hydrolysis and hammer mill refinement is 24%, with a minimum UF resin content of 12%. This study highlights the potential for integrating recycled MDF fibers into new panels, contributing to more sustainable production practices. By optimizing the balance between recycled fiber content and UF resin, it is possible to produce MDF panels that meet industry standards while reducing the environmental impact.