Date of Award

6-1996

Degree Name

Master of Science

Department

Paper Engineering, Chemical Engineering and Imaging

First Advisor

Dr. Raymond L. Janes

Second Advisor

Dr. David Peterson

Third Advisor

Dr. Ellsworth Shriver

Access Setting

Masters Thesis-Open Access

Abstract

The effects of fines level, drying intensity and recycling on pulp and paper properties of bleached softwood kraft were evaluated graphically and statistically.

Fiber fines (100-mesh) were mixed in proportions of 0, 10, 20, 40% with the long fiber fraction. These pulps were tested for fiber length distribution. Handsheets prepared from these pulps were dried at low (air dry) and high (220°F, 4.25 min) drying intensities. These handsheets were recycled and new handsheets were dried at the above drying levels.

Water retention values increased with increasing level of fines for virgin pulp. Recycling resulted in a 20% decrease in water retention values as compared to never dried fibers. Tensile, wet web strength and density increased, while scattering coefficient and tear decreased with fines addition for both virgin and recycled paper.

Results were analyzed considering variables 'fines addition', 'recycling' and 'drying intensity' in the 23 factorial statistical model. Fines addition' and 'recycling' were significant in affecting scattering coefficient and tensile strength, while tear was significantly affected by fines addition at 95% confidence level.

High intensity drying resulted in higher scattering coefficient, lower density and lower tensile than the low intensity drying, suggesting reduced bonding due to high rate of drying and /or "overdrying".

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