Date of Award
Bachelor of Science
Paper Science and Engineering
The objective of this thesis was to determine the most efficient strength of bleach to whiten aged, unprinted news keeping strength loss to a minimum. The paper was aged in natural sunlight on a clothesline at four levels of exposure: No aging, 3 days, 12 days and 24 days. Bleaching sequence used was a two-stage hydrogen peroxide/sodium hydrosulfite. One percent, 2%,and 3% peroxide levels were used. The hydrosulfite was kept at constant 1%. All percentages were based on oven dry fiber.
Results showed an increase in yellowing of the paper with greater sun exposure; one percent peroxide effected a brightness recovery of three to seven days aging. A small amount of natural sunlight radiation does appear to increase paper strength whether pulp is bleached or unbleached. The 12 day aging sample peaked most frequently for all physical testing values.
Miersma, Debra L., "The Reprocessing of Aged Newsprint" (1982). Paper Engineering Senior Theses. 321.