Date of Award

12-1990

Degree Name

Master of Science

Department

Chemical and Paper Engineering

First Advisor

Dr. Ellsworth H. Shriver

Second Advisor

Dr. Raymond L. Janes

Third Advisor

Dr. Raja Aravamuthan

Access Setting

Masters Thesis-Open Access

Abstract

The main objective of this study was to investigate the effect of refining on the brightness of softwood chemithermomechanical (CTMP) and thermomechanical (TMP) pulps. Seven different pulps were refined using a laboratory Valley beater. Brightness, opacity, tensile index, TEA, and fines content of these pulps were determined at four different freeness levels. Scattering (s) and absorption (k) coefficients of these pulps were calculated. One-way analyses of variance (ANOVA) were applied to determine the significance of change in brightness.

Changes in s-values were significantly affected by fiber morphology of different wood species. Refining increased the k-values of the pulps. When the increase in s-value outweighed the increase in k-value, the result was an increase in brightness. Southern pine unbleached TMP showed increases, while bleached CTMP pulps showed decreases in brightness with refining. Other pulps did not exhibit a definite trend. Opacity and tensile strength generally increased with refining.

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