Study on free shrinkage and rheological characteristics of Eucalyptus urophylla ×E. grandis during conventional drying

The collapse-prone nature of eucalyptus wood has implications for the measurement of drying rheological characteristics, particularly free shrinkage. The study outlined the calculation method for drying strain and the determination of drying stress direction. It also analyzed the free shrinkage properties of the wood, as well as the variations in elastic strain, viscoelastic strain, and mechano-sorptive creep strain throughout the drying process. The findings indicate the following: 1, there were no significant differences in free tangential shrinkage between the layers of the specimens. 2, the free tangential shrinkage of the layers was greater than that of the specimens. 3, the use of fresh thin wood that has not been subjected to drying stresses was recommended for accurate measurement of free shrinkage strains, as steaming does not fully reverse the plasticizing deformation caused by drying. 4, the collapse of eucalyptus wood in the early stages of drying hindered the reversal of tensile strain in elastic, viscoelastic, and mechano-sorptive behaviors.