Viscosities of Unbleached Alkaline Pulps. II. The G-Factor

The activation energy for the loss of pulp viscosity (cellulose chain cleavage) during soda-AQ pulping was found to be the same as in kraft cooking: 179 ± 4 kJ/mol. Calculations based on literature data gave a value of 175 kJ/mol for soda pulping. The agreement confirms previous findings that reducing additives do not affect pulp viscosity (η). When high sodium hydroxide charges are employed, straight-line plots of 1/η versus cooking time at maximum temperature are obtained. A “G-factor” is proposed to combine cooking time and temperature into a single variable, similar in concept to Vroom's H-factor, for calculating the effect on pulp viscosity of widely varying cooking cycles.