Evaluation of NSSC and kraft pulps from different average density mixtures of Philippine hardwoods

THE FOREST PRODUCTS LABORATORY OF THE U.S. FOREST SERVICE IS ENGAGED IN SUCH RESEARCH. THIS REPORT PRESENTS THE METHODS AND RESULTS OF RESEARCH TO EVALUATE NEUTRAL SULFITE SEMI-CHEMICAL (NSSC) AND KRAFT PULPS MADE FROM PHILIPPINE HARDWOODS WHICH DIFFER IN THEIR DENSITIES. FOUR PHILIPPINE HARDWOOD CHIP MIXTURES WITH AVERAGE DENSITIES OF 12, 25, 35 AND 45 POUNDS PER CUBIC FOOT WERE PULPED BY BOTH THE NSSC AND KRAFT PROCESSES. THE KRAFT PULPS WERE EASILY BLEACHED TO 90 PERCENT OR MORE BRIGHTNESS USING CEDED. THE HIGHEST NSSC PULP HANDSHEET PROPERTIES WERE OBTAINED USING THE LOWEST AVERAGE DENSITY WOOD MIXTURE, AND ALL PROPERTIES DECREASED AS THE AVERAGE WOOD MIXTURE DENSITY INCREASED. KRAFT PULPS OF MAXIMUM STRENGTH WERE OBTAINED FROM WOOD MIXTURE HAVING AN AVERAGE DENSITY OF 35 POUNDS PER CUBIC FOOT.