Date of Award
Bachelor of Science
Paper Science and Engineering
Lyman C. Aldrich
The purpose of the project was to evaluate pulps made from cherry heartwood and sapwood.
The amount of heartwood a tree has is an individual trait of the tree rather than a function of geography or environment. Tree breeders can, through selection, reduce or increase the amount of heartwood if it is economically justifiable.
Three cherry logs with 50-50 heartwood to sapwood ratio were barked and chipped at S.D. Warren Company in Muskegon. The chips were separated, heartwood from sapwood, by the color difference.
The chips were cooked using 20% active alkali, 6 to 1 liquor ratio, for 1.5 hours at 175◦C using an oil bath digester. The oil bath digester had six cartridges of which three were charged with heartwood and three with sapwood.
The average yield for heartwood was 44.8% and the average yield for sapwood was 52.7%. The difference in yield was the most significant difference between heartwood and sapwood.
The brightness of the sapwood was about 5% greater than heartwood. The Kappa number of the heartwood was 20.8 compared to 22.0 for sapwood.
The mullen of heartwood was greater than the sapwood in the freeness range of 100 to 500 C.S.F. by 12 to 16%.
The tensile of heartwood was greater than the sapwood in the freeness range of 150 to 500 C.S.F. by 4 to 8%.
The tear of sapwood was greater than heartwood in the freeness range of 100 to 500 C.S.F. by 14 to 18%.
You cannot totally eliminate either heartwood or sapwood and the resulting trade-off of advantages of increasing or decreasing the percent of heartwood would likely result in only a couple percent advantages in a few parameters. Therefore, the conclusion of this paper is to leave the ratio of heartwood to sapwood to nature.
Bethke, Craig, "A Comparison of Unbleached Pulps from Cherry Heartwood and Sapwood" (1978). Paper Engineering Senior Theses. 55.