Solid wood utilization of Litchi: Study on physicochemical properties and drying technology

Litchi is an important economic crop with a wide planting area and large yield worldwide. To explore the solid wood utilization value of litchi, this work systematically tested the physical and chemical properties of litchi wood, summarized the drying characteristics using the 100℃-Test Method, and formulated the drying schedule of litchi wood to evaluate the drying quality. The results showed that the drying time of litchi wood from an initial moisture content of 41.38–11.28% was 435 hours, and the drying rate was 0.069%/h. According to GB/T 6491 − 2012 "Sawn Timber Drying Quality Standard," the comprehensive quality grade of litchi wood was grade 2. Dried sawn timber can meet the quality requirements of solid wood furniture and handicrafts. In addition, the porous structure of litchi wood mainly consisted of micro and medium pores, with a porosity of 31.93% and an average pore size of 23.07 nm. The small pore cavities on the cell wall resulted in difficult water transfer, leading to a slow drying speed. However, the porous structure of litchi wood has a positive effect on dimensional stability.In addition, the shrinkage grade of litchi wood was medium, comparable to white oak, ash, and rubber wood under the same environmental conditions. Moreover, the linear and volumetric swelling rates of litchi wood were only higher than rubber wood but lower than white oak. Litchi wood exhibited a larger hygroscopic hysteresis, significantly higher than that of control wood, indicating better dimensional stability. In conclusion, litchi wood is an excellent renewable biological resource and has excellent drying, processing, physical, and mechanical properties, making it a potential candidate for solid wood utilization.