Study On Drying Characteristics And Technology Of Buried Wood Of Toona Sp.from Sichuan

The buried wood is a valuable resource with high value,furniture,handicrafts and other market prospects.But the furniture,handicrafts and other wood for the moisture content of strict,,how to quickly dehydrate dry processing is an issue.In this study,the drying characteristics,such as dry shrinkage,permeability and extract of buried wood of Toona sp.from Sichuan were studied,and the drying characteristics of the Toona sp.wood were compared.The microstructures of the wood cells after ultrasonic pretreatment were observed by scanning electron microscopy(SEM),and the drying technology of the buried wood of Toona sp.was established.The main conclusions of this study are as follows:By dry shrink standard measurement,the air dry tangential shrinkage rate of the buried wood of Toona sp.was 8.07%,the radial shrinkage rate was 3.76%,and the volume shrinkage rate was 13.85%.The dry shrinkage rate was 14.04%,the radial shrinkage was 5.89%,and the volume shrinkage was 20.30%.Compared with the two kinds of materials,the shrinkage rate of the buried wood of Toona sp.is larger than that of the redwood.The air-dry shrinkage ratio of tangential to radial is more than 2,and the deformation in the process of drying the wood is more than that of the Toona sp.wood.When the moisture content of the drying process was about 80%,the shrinkage rate of the buried wood of Toona sp.began to increase gradually,and finally reached the maximum dry shrinkage rate,and did not meet the fiber saturation point theory.After elemental analysis,the density of the buried wood of Toona sp.is greater than that of the Toona sp.wood,and the buried wood of Toona sp.was long in the underground special environment.Some of the substances containing inorganic mineral elements into the wood so that the density increases,so it is suitable for the furniture.Through the gas permeability test,the permeability of the buried wood of Toona sp.in the same position,the same direction and the same moisture content were lower than those of the the Toona sp.wood.The permeability of the sapwood is higher than that of the heartwood,which is related to the inclusion of more inclusions in the heartwood and the sapwood.The main structure of the wood has played a role in the permeability.The permeability of the buried wood of Toona sp.was the minimal at 110% moisture content,and the maximum at 12% moisture content.As the moisture content decreases,the gas permeability gradually increased.When the moisture content decreased from 110% to 80%,50% and 12%,the difference between the vertical permeability and the horizontal permeability was increased from one order of magnitude to two orders of magnitude.Measured by wood extract test,the heartwood content of extracts of the buried wood of Toona sp.were higher than that of sapwood.The reason for the difference in wood permeability is multifaceted,which is related to the structure of the wood itself and the content of the extract.The content of the extract of the two kinds of wood's heartwood is larger than that of the sapwood,and the permeability of the heartwood is less than that of the sapwood.So the extract content will have a certain impact on the permeability of wood,was the opposite direction of the relationship between the change,that is,the higher the extract content,the corresponding permeability of the smaller.Through the ultrasonic treatment,the vertical,tangential and radial permeability of the buried wood of Toona sp.were improved by 1-2.5 times.When the ultrasonic power is 300 W and the water temperature is 50?,the treatment time is 3h,the improvement of wood gas permeability is the best.After ultrasonic treatment,the wood pit opening to varying degrees,as well as the pit cell loose,the deposits on the pit membrane to reduce.Part of the vessel cell wall was loose,cracking and other phenomena.These are favorable for the flow of fluid within the wood,which improves the effectiveness as an airflow channel,thereby improving the permeability.Ultrasonic treatment improves the permeability of the buried wood of Toona sp.and enhances the drying rate.The drying time of the processing group was 15.63% shorter than that of the control group.The buried wood of Toona sp.less drying defects by ultrasonic treatment.Ultrasonic treatment helps to improve the drying characteristics,making the plate dry quality better.