Comparative Study on the Sizing Efficiency and Kinetics between ASA and AKD Sizing

Wilhelmy technique was used to measure the single fiber advancing contact angle of AKD and ASA sized pulp fibers. When sizing performance was fully developed, the advancing contact angle of AKD sized pulp fiber was 85°, while the ASA sized pulp fiber was 95°. Waterdrop absorption measurement also indicated that ASA was a more efficient sizing agent than AKD. The single fiber advancing contact angle was linearly proportional to the AKD and ASA dosage until sizing performance was fully developed.Lindstrom and co-workers have studied the esterification kinetic constant of AKD, while Marton has investigated the hydrolysis kinetic constant of AKD. We studied the esterification and hydrolysis kinetic constant of ASA. It was found that the esterification kinetic constant of ASA was three times that of AKD (pH=6.0). Similarly the hydrolysis kinetic constant of ASA was 40 times that of AKD (pH=8.0). Proper appreciation of the kinetic aspects of sizing should be helpful to optimize the sizing performance of ASA and AKD.