Date of Award

4-1998

Degree Name

Bachelor of Science

Department

Paper Science and Engineering

First Advisor

Dr. Peter Parker

Second Advisor

Dr. Rob Eversol

Abstract

As paper mills took to reuse as much internal waste as possible, problems in the system can be introduced. The buildup of deposits or fluctuations of chemicals can occur when more broke is introduced. In mills that add a layer of coating to the paper problems associated with the coating can be introduced. At Champion International in Hamilton, Ohio, a heavy layer of coating added to the sheet introduces the problem of coating flakes to the system.

It was hypothesized that the use of the ultrasonic cavitation mechanism should be able to break the flakes apart and reduce the overall size of the flakes. In this experiment, pulp consistency and ultrasonic exposure time were varied. The frequency and the power of the ultrasonic device were constant. The specific energy for each condition was found and reported as power index. The flake count and area were measured by image analysis. As the power index is increased, the amount of coating flake area should decrease. A secondary effect of the ultrasonic power variation may be fiber fibrillation. This results in a stronger sheet.

Experimental results indicate that ultrasound can indeed break large coating flakes apart and reduce the average size of the flakes. The number of coating flakes in a specified size range was reduced. This indicates the ability of the ultrasound to reduce coating flake size. The tensile and tear indexes increased which suggests that ultrasound can fibrillate the fibers. This fibrillation gives an increased bonding area and allows for better bonding or a stronger sheet.

Statistical analysis shows that the ultrasound treatments are significantly different from a sample that was not treated. Overall, ultrasound can decrease the size of coating flakes and increase the tensile and tear strength of a sheet of paper.

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