Author

Devisetti

Date of Award

6-1999

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. Peter E. Parker

Third Advisor

Dr. John H. Cameron

Access Setting

Masters Thesis-Open Access

Abstract

The effect of multiple recycling on strength properties and fiber properties like strength of fiber, weighted average fiber length, fines percentage and water retention values were investigated in this study. Borax was used as a strength aid and swelling agent to improve the flexibility of fiber and strength of recycled paper. Bleached softwood kraft pulp was used to make the hand sheets and recycled repeatedly for up to four cycles. The main objectives were to evaluate the chemically treated pulp and untreated pulp at each stage of recycling, to study the effect of multiple recycling on strength properties of paper and to find out whether the bonding ability of borax helps in improving the strength properties during recycling.

Recycling affects negatively the bonding potential and swelling properties of pulp. The loss in strength properties is related to the loss in bonding potential of fibers, as there was no evidence of major change in fiber length or intrinsic strength of fiber. Addition of 1% borax to the virgin stock and recycling further showed a significant improvement in tensile strength and retained the bonding or swelling potential of borax only up to first recycle. Addition of 1% borax to the secondary fibers showed a slight improvement in water retention values and not much improvement in strength properties in any of the four recycling stages.

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