Date of Award

4-1997

Degree Name

Bachelor of Science

Department

Paper Science and Engineering

First Advisor

Dr. Dewei Qi

Abstract

Mechanical and chemical pulps are the dominant pulping methods used throughout the pulping industry. The increasing demand for the use of recycled fiber both by public and government legislation provides incentive for research concerning recycle fiber use. Currently, research has been performed on chemical pulps and only very little on mechanical pulps. The focus of this experiment was to determine the subsequent effects of refining on recycled pulp and paper without thermal interaction. From the majority of the data analysis, a conclusion concerning the optimum number of times a fiber could be recycled before severe degradation was three. Determination regarding loss of bonding versus fiber strength was also made. The zero span tensile strength test indicated a loss of strength gradually with the greatest loss after the third recycle. The Scott bond strength test yielded results that showed a gradual increase in bonding strength and then a sharp decline after the third recycle. Some additional strength property testing yielded results that include an increase in tensile index, burst strength, and a decrease in folding strength. Optical properties were also examined for their variations due to recycling and refining. The opacity increased with the onset of refining leveling out after the third recycle. The brightness of the sheets gradually decreased, the roughness of the sheet exhibited a gradual smoothing with the subsequent recycles, the scattering coefficient increased and then showed a gradual decrease with recycle number

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