STUDY OF CHEMI-MECHANICAL PULPING OF EUCALYPTU.S .PULP

Abstract

Mechanical pulping"produces some desirable properties with in the pulp, which are very useful in many grades of papers. This also gives pulp with higher yield at relatively lower cost. Chemi refiner mechanical pulping (CRPM) of Eucalyptus chips`'was tried using different chemical" composition in p"reimpregnation.stages for different- time and temperatures. The results indicated that preimprignation at6% NaOH, under atmospheric condition for 24 hours followed.by,heating for 2 hours at 80°C temperature gave better results. - `Th.e chips were refined in Sprout Waldran Laboratory Refiner with single rotating disc of 12 inches diameter and it was observed that 4 pass refining with decreasing clearance gave better results. The pulp was evaluated for strength and optical properties for optimizing the above parameters. The (CRMP) was bleached by single stage Hydrogen Peroxide bleach-ing and brightness up to 50% was obtained. It was also observed that brightness enhancement also takes place using H202 in preim-prignation-stage by which one stage of bleaching after refining can be reduce to obtain final brightness of pulp. The work was extended to Bagasse CRMP and strength and optical properties of Bagasse pulp make under different preimpre,snation and refining were studied. It was again observed that a CRMP pulp made with 6% NaOH under atmospheric condition for 24 hours soak-ing followed by 2 hours heating at 80°C temperature, gives better results. From the results"obtained, it is evident that Chemi.-Refiner Mechanical pulp so obtained from Eucalyptus and Bagasse are suitable for supplementing the newsprint manufacturer.