抄録
Interactions between chemical species (pulp, alum and/or PAM (polyacrylamide)) contained in a pulp slurry were investigated by means of chemical analysis and optical microscopy. After rapid filtration of pulp slurry containing alum the aluminum content in pulp was drastically changed around pH 4.5. In the pH region from 5 to 7, aggregates measuring several ten microns in diameter were observed in the slurry, but in the filtrate aluminum was hardly detectable. The aggregates interacted strongly with amphoteric PAM and weakly with pulp. We proposed a hypothesis which chemically describes the process from preparation of slurry to evaluation of paper through paper making. Aggregates derived from alum control the amount and position of amphoteric PAM in paper.
The amount of PAM in paper increased with increasing amount of alum in slurry in the pH 5 to 7 region, while in alum-free systems decreased with increasing pH in the same region.
We found that phosphomolybdic acid easily dyes PAMs blue or green, and first succeeded to observe the PAM morphology in paper by means of the scanning electron microscopy.
