Mini-Encyclopedia of Papermaking Wet-End
Part Three: Equipment & Unit Operations
The word coagulation refers to the coming together and sticking of finely divided particles or droplets due to the addition of ionic materials. The principle mechanisms used to bring about coagulation are (a) neutralization of surface charges, and (b) screening of electrostatic repulsions by increasing the electrical conductivity of the solution. Coagulated dispersions or emulsions tend to settle or cream. The coagulation mechanism by itself is seldom sufficient to ensure retention of fine particles during paper manufacture. The word "flocculation" is more often used when one is referring to treatment with retention aids that are capable of forming shear-resistant bonds between fine particles, fiber-fines, and fibers.
Request from the webmaster: Our goals include brevity and accuracy. Hopefully we have succeeded with the first goal without sacrificing the second. Please let us know right away if you find an error or omission. Also, please indicate points that need a clearer description.
RETURN TO INDEX PAGE OF ENCYCLOPEDIA
This page is maintained by Martin hubbe, Associate Professor of Wood and Paper Science, NC State University, firstname.lastname@example.org .