Importance of dry-strength additives

It is generally accepted that van der Waals forces, hydrogen and ionic bonds are the most important interactions contributing to the diy-strength development in paper [64,69]. 

The strength of paper depends on the strength of the individual fibers and on the strength of the bonds between fibers. The number of bonds and the distribution of the bonds and fibers (i.e., the formation] are also important Dry-strength additives may enhance one or more of these features but not the strength of individual fibers [17]. 

A diy-strength additive should be water-soluble pol nner, preferably a cationic one, and should be able to form hydrogen bonds. Actually, wood fibers contain their own dry-strength additive— hemicelluloses. It is well known that the hemicelluloses contribute to the development of paper bonding properties. 

Diy-strength additives are generally water-soluble, hydrophilic pol5miers, either natural or synthetic. The most common additives used in paper industry are as follows  

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