Recycling of Waste MDF by Steam Refining: Evaluation of Fiber and Paper Strength Properties

Abstract

Currently, most of the collected waste medium-density fiberboards (MDF) is incinerated or landfilled, as economically viable recycling methods are yet to be developed. By steam refining waste medium-density fiberboards (MDF), it is possible to hydrolyze the incorporated resins and isolate a high yield fiber fraction. Further refining of the steam treated fibers might enable the fibers to be utilized in applications such as paper packaging, facilitating a cascading use of the waste material stream. To this end, intimate knowledge of the material is needed. In this study, the steam refined fibers of two waste MDF samples containing differing amounts of softwood and hardwood underwent refining and beating. The resulting fibers were characterized regarding their morphology and paper test sheets were produced to evaluate their strength (compression-, tensile- and tear-strength). Distinct differences in response to refining between the MDF samples were apparent. For the sample with the higher hardwood share an increase in strength properties with increasing steam treatment severities could be observed and it was possible to produce test sheets with comparable compression strength to recycled pulp for industrial corrugated paperboard. For the sample with a higher share of softwood, the steam treatment severity did not show any influence on fiber morphology or paper properties, and the resulting paper strength was low in comparison to the other steam refined waste MDF sample. Graphic Abstract

Cascading Recycling of Wood Waste: A Review

“…An effective process to homogenize wood waste is defibration. Fibers are good candidates for the development of new recycling routes [ 36 , 37 , 38 , 39 ] as they are the raw material for many products, such as paper, MDF (medium-density fiberboards), and wood fiber-based insulation boards (commonly called “wood wool” in reference to their glass or rock wool equivalent), already on the market. Other applications of wood fibers also exist such as the reinforcement of composites (plastic, concrete, etc.)…”

Analytical Characterization and Inhibitor Detection in Liquid Phases Obtained After Steam Refining of Corn Stover and Maize Silage

“…In the last years steam refining was conducted for pretreatments of wood ( Schütt et al, 2011 ; Schütt et al, 2012 ), forest residues ( Janzon et al, 2014 ), CS ( Krafft et al, 2020a ), MS ( Krafft et al, 2020b ) or waste medium density fiberboards (MDF) ( Hagel and Saake, 2020 ). Most studies were conducted to enhance the enzymatic digestibility for the production of monomeric carbohydrates, but attempts for MDF fiber recycling after steam refining are reported as well ( Hagel et al, 2021 ).…”

Valorization of Urban Street Tree Pruning Residues in Biorefineries by Steam Refining: Conversion Into Fibers, Emulsifiers, and Biogas

“…In such cases, high treatment severities of four or higher are optimal ( Limayem and Ricke, 2012 ; Zabed et al, 2016 ). Alternatively, the fibers might be useable in paper applications after further processing ( Kokta and Aziz, 1998 ; Hagel et al, 2021 ). As the demand for paper-based packaging material is expected to remain high due to the surge in e-commerce, and hardwood fibers are known to be short and stiff in comparison with softwood fibers ( Twede et al, 2015 ), an incorporation of the fibers in the production of corrugated paperboard could be an environmentally friendly and economically viable utilization of the fibers.…”