Date of Award
Bachelor of Science
Paper Science and Engineering
Dr. Raymond L. Janes
Alkenyl succinic anhydride (ASA) is a cellulose reactive size used in neutral to alkaline sizing. ASA is emulsified in cationic starch to help retain the ASA on the fiber and to protect the ASA from hydrolysis. The stability of the ASA emulsion is largely dependent upon temperature, pH, and shear.
While one of the advantages of alkaline papermaking is the elimination of aluminium from the process water, the addition of small amounts of alum has proven beneficial to some mills running ASA size. The advantages claimed by using alum are: improved sizing, improved retention, and improved runnability.
The aluminum species formed depends primarily upon pH. There are three pH regions of major concern: a low pH region (pH less than 4.3), an intermediate pH region (pH 4.3-5.0), and a high pH region (pH 5.0-8.0). The predominate aluminum species formed in these different pH regions are Al+3, Al8(OH)204+, and Al(OH)3, respectively. The effect of these three aluminum species on ASA sizing was studied to better define the role of alum in ASA sizing.
The results showed that the low pH region alum improved sizing. In the intermediate and high pH region, the results showed that alum had little effect at low concentrations; however, at higher concentrations alum decreased sizing.
Keywords: Alkaline papermaking, alum, aluminum, Alkenyl Succinic Anhydride (ASA), sizing
Farrand, James A., "The Effects of Alum at Different pH Levels on ASA Sizing" (1986). Paper Engineering Senior Theses. 123.