Numerous wood densification processes have been developed to improve physical and mechanical properties. Wood densification in general reduces void volume by compressing the wood to increase wood density. However, the unstable nature of this type of compressed wood allows it to almost regain its original shape entirely when re-moistened. In the woods’ ultrastructure, hemicellulose and amorphous cellulose are more hydrophilic than lignin. In contact with moisture, there is an interaction between hemicelluloses (fixity) and lignin (recovery). Given that lignin has a dominant role in shape memory, the investigation of partial delignification and its impact on set-recovery is appealing. Additionally, there has been little research on densification at low temperatures and higher moisture contents. Energy-efficient and productive densification at low temperatures is a valuable proposition. Therefore, establishing how springback and set-recovery are affected by the amount of lignin in wood and pressing conditions are the key goals of this research.
Keywords: Densification, delignification, set-recovery
Authors
Catherine Kilumets
Laboratory of Wood Technology, Department of Material and Environmental Technology, Tallinn University of Technology, Tallinn 19086, Estonia
Sally Ralph
USDA Forest Products Laboratory, Madison, WI 53726, USA
Peter Kitin
USDA Forest Products Laboratory, Madison, WI 53726, USA
Carlos Baez
USDA Forest Products Laboratory, Madison, WI 53726, USA
Nayomi Plaza
USDA Forest Products Laboratory, Madison, WI 53726, USA
J. Y. Zhu
USDA Forest Products Laboratory, Madison, WI 53726, USA
Christopher G. Hunt
USDA Forest Products Laboratory, Madison, WI 53726, USA
Heikko Kallakas
Laboratory of Wood Technology, Department of Material and Environmental Technology, Tallinn University of Technology, Tallinn 19086, Estonia
Jaan Kers
Laboratory of Wood Technology, Department of Material and Environmental Technology, Tallinn University of Technology, Tallinn 19086, Estonia
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