Process of Soda-AQ Pulping of Fast-Growing Poplar and Defibration Point

Abstract

Fast-growing Poplar cooked by Soda-AQ process was studied, by determining the lignin contents including Klason lignin and acid soluble lignin, the yield of pulping, the rate of carbohydtare degradation and the rate of delignification.Results indicated that the delignificaton of Fast-growing Poplar in Soda-AQ pulping can be divided into three distinguishable stages. (a)The initial delignification stage before 140°C,the rate of delignification reaches to 30.87%;(b)The bulk delignification stage, the rate of delignification reaches to 86.97%，in the period from 140°C to 170°C and for 30 min;(c)The residual delignification stage,the rate of delignification exceeds 91.60%. The defibration point was reached when cooking temperature raised to 170°C and for 30 min with 57.50% pulping yield ,24.94 kappa nomber.