Date of Award
Master of Science
Chemical and Paper Engineering
Paper Engineering, Chemical Engineering and Imaging
Dr. Raja Aravamuthan
Dr. Raymond L. Janes
Dr. Ellsworth Shriver
Masters Thesis-Open Access
High-yield mechanical pulps possess high opacity, bulk, compressibility, and excellent printing properties as well. But these pulps are still not suitable for producing high-grade papers because of discoloration. The brightness with age may be due to the presence of lignin, hemicellulose (and even cellulose), resins, metal ions, and additives such as rosin, alum, starch, and other polymers.
This study includes the effects of different metal ions on brightness stability of wood, thermomechanical pulps, chemithermomechanical pulps, and alkaline peroxide mechanical pulps. Also studied were the influences of metal ions on bleached pulps towards brightness loss. The metal ions selected for this study were iron, copper, aluminum, and calcium.
The rate of brightness reversion among mechanical pulps is influenced by the presence of transition metal ions. However, the concentration of metal ions beyond 400 parts per million in mechanical pulps showed a little or no difference in the rate of discoloration. The presence of iron in wood samples was most damaging when combined with the heat irradiations. However, calcium ion in wood samples actually improved the brightness stability by light at elevated temperatures.
Jain, Ajay K., "Influence of Metal Ions on Brightness Reversion of Mechanical and TMP Pulps" (1997). Masters Theses. 4925.