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Maderas. Ciencia y tecnología

On-line version ISSN 0718-221X

Abstract

ACUNA, Sergio M  and  TOLEDO, Pedro G. SURFACE FORCES AND ADHESION IN CELLULOSE SYSTEMS: NEW WAY TO EVALUATE RESIN FIXATION/DISPERSION IN THE MANUFACTURE OF PAPER/CELLULOSE. Maderas, Cienc. tecnol. [online]. 2010, vol.12, n.3, pp.209-228. ISSN 0718-221X.  http://dx.doi.org/10.4067/S0718-221X2010000300006.

Surface and adhesive forces between colloidal wood particles of resin and fiber dominate the behavior and final properties of paper and cellulose. This paper describes the use of Atomic Force Microscopy (AFM) to measure the interaction force between a resin "functionalized" substrate and a glass microsphere in aqueous pH-controlled electrolyte solutions at ambient temperature. The water-wet made substrate is a hydrophobic polystyrene film coated with an extremely thin film of wood fatty and resin acids. The surface charge on the "functionalized" substrate mimics that on resin micelles, the preferred microstructure of resin in water, and the charge on the microsphere mimics that on wood fibers. AFM force curves are analyzed to the light of the balance between attractive forces -van derWaals- and repulsive forces -electrostatic- from the classical continuum DLVO theory of colloidal forces. Force measurements show strong and persistent short-range repulsive forces at distances less than 100 Å which are not explained by the DLVO theory. These repulsive forces that act as barriers to contact or coagulation originate on highly ordered water in the neighborhood of the charged surfaces. The barrier size and intensity depend on the magnitude and density of the electrical charges on the interacting surfaces, which in turn depends on their chemical composition, and on the aqueous media. Repulsion increases with pH and decreases with electrolyte concentration. AFM flat-microsphere pull-off forces reveal an apparently unreported correlation between electrolyte concentration and adhesion. Adhesion increases with electrolyte concentration and size. Complex phenomena such as dusting, the release of resin upon paper use due to poor resin-fiber bondage, can thus be controlled by regulating the aqueous media during papermaking.

Keywords : AFM; nanoforces; resin; pitch; bondage; adhesion; papermaking.

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