Date of Award

4-1993

Degree Name

Bachelor of Science

Department

Paper Science and Engineering

First Advisor

Dr. Raymond Janes

Abstract

This project was designed to study the impact of drying on the properties of fiber fines. Three different drying conditions were used: force-dry (0% moisture), force-dry (6% moisture), and air-dry (6% moisture). Fines were evaluated in the paper and in the pulp both before and after recycling.

In order to study the impact of drying on the fines, fines were removed from the virgin furnish. Characteristics of the control stock containing fines and of the control stock without fines were evaluated and served as a means of comparison. Stocks were tested for wet-web strength, drainage, freeness, and water retention value. Two sets of handsheets (fines-free and fines-containing) were made at each condition. Handsheets were evaluated for brightness, opacity, scattering coefficient, absorption coefficient, density, and tensile index. Handsheets were then repulped and tests were performed, as before, on the stock. All recycled pulps were then used to prepare air-dry handsheets which were evaluated again for strength and optical properties.

Results show that force-dry (0% moist) fines, both before and after recycling, contributed the most to density and tensile index because of lower fines-free values, but the least to wet web strength. Force-dried fines were less active than air-dried fines but more necessary because of this. Air-dried fines were more active and had the lowest scattering coefficient and CSF, and had the strongest wet-web and paper. Bonding potential was reduced in all cases by drying, as indicated by lower densities, tensile indexes, wet-web strengths, and water retention values.

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