EFFECTS OF TEMPERATURE AND SULFONATION ON SHEAR DEFORMATION OF SPRUCEWOOD

The effects of temperature and sulfonation on the deformation of spruc e wood at conditions comparable to those during screw press impregnati on prior to mechanical pulping were studied using a dynamic testing me thod. In addition to the physical properties of wood, shear fracture s urfaces obtained at different deformation temperatures and at differen t sulfonation levels were studied using scanning electron microscopy ( SEM). The results showed that the failure energy of wood decreased gra dually with increased deformation temperature in the tested range of 2 0-95 degrees C, due to thermal softening of the material. In addition to thermal treatment, the failure energy could also be reduced by sulf ite treatment of the wood before deformation, and decreased with incre asing sulfonation degree. The SEM analysis showed that increasing the deformation temperature causes the fracture plane to travel around the fiber walls instead of through them, thus exposing a smoother wood su rface with less fiber damage. At a given deformation temperature, part icularly at the lower temperatures, sulfonation improves fiber separat ion.