Sizing Mechanism of Hydrophobically Modified Polyacrylamides

A new reactive surfactant (ASA-MA) is found to provide polyacrylamides (PAM) hydrophobic characters. Hydrophobically modified PAM (ASA-PAM) is available for surface size, and the sizing mechanism of ASA-PAM was investigated. The sizing ability of ASA-PAM is dependent on the presence of alum in the paper. The copolymers of ASA-MA and some nonionic water soluble monomers were synthesized, and the sizing abilities and the paper strength abilities were examined. The sizing mechanism is assigned to proceed two steps, that is, ASA-PAM combined with the alum in the paper in the first step, and hydrogen bond between ASA-PAM and the pulp are formed in the next step, and such interactions resulted in the orientation of the hydrophobic groups to the air surface.Applications of ASA-PAM as dispersing agent or retention agents to SBR latex are also described.