Wet-peel: a tool for comparing wet-strength resins

Abstract We propose that a testing procedure we call wet-peel significantly augments conventional wet paper testing when comparing wet-strength resin efficacy or the influence wood pulp fiber surface treatments on wet paper strength. A thin layer of wet-strength resin is sandwiched between a pair of thin, wet regenerated cellulose membranes to form a laminate, which is a physical model for fiber-fiber joints in paper. In the wet-peel method, the ninety-degree wet-delamination force gives a direct measure of adhesion in the wet cellulose-cellulose joint. Wet-peel measurements offer: 1) comparisons of wet-strength polymers at the same content of polymer in the laminate joint without the influences of varying fines contents, formation or paper density; 2) measurements of both the wet-strength of cured, dried joints, and the strength of never-dried joints (i. e. analogous to wet-web strength); 3) demonstrations of the influence of fiber surface chemistry modifications including oxidation and the presence of firmly bound polymers; and, 4) the evaluation of more exotic joint structures including layer-by-layer assemblies, microgels and colloidal polyelectrolyte complexes.