ULTRA-HIGH-YIELD PULPING OF EUCALYPTUS-GLOBULUS - INFLUENCE OF IMPREGNATION CHEMICALS

Eucalyptus wood increasingly becomes the most important source of fibe r for paper industry in many tropical and subtropical countries. Chemi cal impregnation of eucalyptus chips under moderate to strong alkaline conditions is necessary to prepare ultra-high-yield pulp. The most po pular process for high-yield pulp of eucalyptus is cold soda pulping. The impregnation liquor consisting of NaOH, NaHCO3 or Na2CO3, along wi th Na2SO3, influence total ionic content, yield and properties of pulp . NaHCO3 in impregnation liquor is an effective chemical used to prote ct the fiber against hydrolysis and degradation, resulting in high pul p yield and brightness. The total ionic content of pulp increases with the NaHCO3 concentration in the impregnation liquor, resulting in hig h tear and breaking length values. The pulp yield and brightness drop drastically with the NaOH concentration in impregnation liquor. The to tal ionic content of the pulp decreases sharply with the NaOH concentr ation in the impregnation liquor. However, the breaking length and tea r index of the pulp rise sharply with the NaOH concentration of up to 2%, and then stabilize with further concentration. The pulp yield and brightness drop with the rise in the Na2CO3 concentration of the impre gnation liquor. The tear index and breaking length of the pulp increas e simultaneouly for NaOH in impregnation liquor. However, the tear ind ex remains fairly constant even with the increase in breaking length w hen the impregnation liquid contains Na2CO3 or NaHCO3.