Fiber Characteristics, Pulpability, and Bleachability Studies of Switchgrass, 1996 Pulping Conference Proceedings

Theodore Radiotis and Jian Li

Pulp and Paper Research Institute of Canada

Krishan Goel and Reinhold Eisner

Domtar Inc.

Due to increasing concerns for future fiber supplies and last years increase in wood cost, has strengthened the pulp and paper industry’s interest in alternative pulp fiber sources, i.e., annual plants. Amongst many of them, switchgrass (Panicum virgatum), a native North American grass, stands out as an excellent candidate because of its high crop yield (10-12 T/ha/annum), chemical composition, extractives, and low ash content. In order to assess its paper-making potential, a systematic study was conducted that examined: (1) fiber characteristics (2) pulpability, (3) bleachability, and (4) physical properties. The fibers were characterized using light and scanning electron microscopy, Kajaani fiber optic analyzer, and Bauer-McNett classifier. These techniques revealed that the pulp contains (1) a high amount of fines; and (2) fibers with a wide distribution of fiber lengths and thick fiber walls. The material was easily pulped using the kraft process with acceptable pulp yields, i.e., a 50% total yield with a kappa number of 14. The burst, tear and tensile strengths and freeness were typical of non-wood fibers. The pulp was readily bleached using conventional (C + D E D E D), elemental chlorine free, ECF (O D Eo D), and total chlorine free, TCF (0 Z E Q PO), sequences giving brightnesses greater than 85%.