The Wet Adhesion of Polyvinylamine to Cellulose

Abstract

<p>A systematic investigation of Polyvinylamine (PVAm) as a strength-enhancing polymer for wet paper was undertaken through the development of a new test method that simulates the influence of polymers on fibre-fibre bonding in paper. Pairs of wet regenerated cellulose membranes were laminated using the paper strength-enhancing polymer as the lamination adhesive. The resulting laminates served as a physical model for fibre-fibre bonds in paper and the wet laminate strength was determined by ninety degree peeling experiments. Key experimental parameters and sources of error were identified.</p> <p>The mechanism of PVAm paper wet strength enhancement was explored by the wet cellulose delamination procedure. Initial results showed that PVAm was a poor wet adhesive for cellulose unless the cellulose was lightly oxidized. The adhesion was found to be a strong function of the concentration of amine and of the cellulose oxidation products. This led to the hypothesis that there are two mechanism in action; the first being the well-accepted electrostatic bonding theories and the second being covalent bond formation between acetal/hemi-acetals/aldehydes and the amine.</p> <p>A thorough investigation of the surface chemistry and morphology was conducted to confirm the hypothesis of covalent bond formation between aldehydes and amines. Oxidized regenerated cellulose was laminated with PVAm and the peeled surfaces analyzed by X-ray Photoelectron Spectroscopy (XPS). It was shown that the wet delamination force correlated to the acetal/hemi-acetal/alehyde surface concentration. It was concluded that the delamination force would be increased by a cumulative strengthening of both the cellulose surface and adhesive interface.</p>