Date of Award

4-1997

Degree Name

Master of Science

Department

Chemical and Paper Engineering

Department

Paper Engineering, Chemical Engineering and Imaging

First Advisor

Dr. Raja Aravamuthan

Second Advisor

Dr. Raymond L. Janes

Third Advisor

Dr. Ellsworth Shriver

Access Setting

Masters Thesis-Open Access

Abstract

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.

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