Reaction phases of the wood constituents’ degradation during kraft cooking of spruce chips
In this study, the changes of the individual constituents of wood, mainly lignin fraction, and carbohydrate fraction of partially delignified wood chips were investigated. The concentration of alkali during kraft cooking of spruce chips were characterized with respect to the time of kraft cooking, consumed alkali and also to the time-temperature variable (H-factor). The observation brought a new fact, that the extraction of lignin and degradation of the carbohydrate fraction as well as the wood residue itself, were realized in two different reaction phases: initial and residual. The power form dependences between the studied constituents of the wood during kraft cooking were interpreted in a logarithmic coordinate system by the straight line relationship.