Лесотехнически Университет

Резюме

Production of Medium Density Fibreboards (MDF) is one of the growing woodworking industries. It has been found that a quarter of the produced MDFs have a life cycle of up to five years, and by ten years, this amount has increased to fifty percent. There is no established industrial practice for recycling that type of waste. That, together with the fact that some countries have banned the dumping of these panels in landfills, poses significant challenges.

There are currently two main research directions on MDF recycling, namely with and without pre-treatment. In both cases, with an increase in the content of recycled fibres, a deterioration in the properties of the panels is observed. Still, the share of cut fibres and formaldehyde emissions from the boards are reduced during the preliminary treatment, mainly by hydrolysis.

In the present manuscript, a review and analysis of MDF recycling methods are performed. On that base, conclusions and recommendations are derived.

Резюме

Recycling Medium-Density Fiberboard panels is a significant challenge and is not a widespread industry practice. Given the reduced costs, the methods for recycling this material with hydrothermal hydrolysis of the resins are more promising than those with acid hydrolysis. Despite the considerable amount of research on the topic, the effect of the hydrolysis regime on the stiffness and deformation at the bending load of recycled MDF panels (rMDF) remains limited.

In the present work was conducted a study on the effect of hydrothermal hydrolysis regime, with a variation in temperature from 121°C (saturated steam pressure 0.2 MPa) to 134° (saturated steam pressure 0.3 MPa) and the hydrolysis time from 30 min to 60 min on the stiffness and deformation behaviour of rMDF. It was found that the stiffness of the panels was not significantly affected by the hydrolysis regime, but the rMDF had about ten per cent less stiffness than the control panel from natural fibres. It was determined that the optimal hydrolysis regime is at 121° and has a processing time of 30 minutes. Concerning the investigated rMDF characteristics, it is not recommended that the panels be composed entirely of recycled fibres.