Research progress of thermo-mechanical compression techniques for wood products

TU Dengyun;CHEN Chuanfu;ZHOU Qiaofang;OU Rongxian;WANG Xianju;College of Materials and Energy,South China Agricultural University;

wood compression;;wood softening;;deformation modification;;wood compression process;;compressed wood properties

In recent years,the application of fast-growing wood has gradually become the only way for the development of the forestry economy and the furniture manufacturing industry. Fast-growing wood species,such as poplar,eucalyptus,China fir,and Scots pine,have become promising alternatives in the wood processing industry. However,the undesirable inherent disadvantages of fast-growing wood,including loose texture,inferior mechanical properties,and dimensional instability,resulted in a low degree of utilization as value-added solid wood products,which significantly limit its scope of applications. Consequently,it is definitely necessary and important to improve the fastgrowing wood with inferior mechanical properties and dimensional instability. To overcome the drawbacks of the fastgrowing wood and to improve its utilization value,different effective modification methods have been implemented,mainly including thermo-hydro modification,thermo-hydro-mechanical modification,and chemical modification.Thermo-mechanical compression technique,one of the physical modification methods,has the advantages of high production efficiency,no chemical pollution,and easy industrialization. It is one of the wood modification techniques with the most potential commercial value in expending the application range of the fast-growing wood and has become the frontier and hot topic in the research field of wood modification. In this review,the representative achievements about the thermo-mechanical compression technique and compressed wood are presented and summarized,including the category of thermo-mechanical compression,wood softening methods,fixation methods of compression deformation,compression process control,and performance and application of the compressed wood. Finally,some existing problems of the thermo-mechanical compression techniques are presented,as well as the potential development directions are prospected. The thermo-mechanical compression technique should be further developed in aspects with high-efficiency and multi-function,and the evaluation analysis of the value chain from forest to compressed wood should also be considered. This will be of great significance to promote the commercial development of thermo-mechanical compression technique and realize the high value-added utilization of compressed wood. The compressed wood with excellent performance and good dimensional stability can be used as flooring,furniture components,wooden crafts,and the compressed wood blocks can also be used to improve the strength of glulam beams. It is expected that this review article can provide some inspirations for the wood research in the future.