Characteristics of kenaf and its behaviour during sulfate pulping

The optimum alkali charges are of 16%. 18% and 14% (based on Na2O), and the points of fiber liberation occur at pulp yields of 51%, 48% and 55%, respe ctively, for the whole stalk, core and bast of kenaf in sulfate pulping. Th e delignification processes of sulfate cooking can be divided into three ph ases. The delignification activation energies in bulk delignification phase s are 107.5 KJ/mol and 81.6 KJ/mol respectively, for the core and the bast. Although the core fiber is shorter, but has thinner cell walls, wider lume ns, and higher hemicellulose content, the core pulp is easier to bear, and has rather high tensile, bursting and folding strengths. On the contrary, t he bast fiber is longer with thicker cell walls and narrower lumens, and th erefore the bast pulp has higher tearing strength. However, the whole stalk pulp has higher strength properties than those of either core pulp or bast pulp, due to the coordination of two types of fibers.