The wetting behaviour of a commercial starch-stabilized alkylketene dimer (AKD) emulsion on glass was investigated by atomic force microscopy (AFM). The primary objective was to elucidate whether or not the starch and surfactant used to emulsify AKD could enhance AKD wetting on a hydrophilic surface to such a level as to allow complete spreading (θE = 0); AKD wax was not previously known to spread on glass nor on cellulose. The secondary objective was to estimate the fraction of the furnish wetted by AKD droplets. Temperature is the primary variable affecting AKD wetting. The extent of AKD wetting increases with temperature up to 70 °C, after which wetting reaches equilibrium contact angles not differentiable by AFM. AKD wets glass to a finite contact angle (θE>0); spreading (θE = 0) was never observed with the commercial AKD suspension. The drying process also influences the extent of AKD wetting on glass. This is explained in terms of AKD hydrolysis, starch desorption from AKD and starch adsorption on the glass, which modifies the interfacial energies and, thus, the equilibrium contact angle. The fraction of the furnish wetted by droplets (x) and the average distance between two AKD droplets (L) was calculated for three examples.
|Number of pages||8|
|Journal||Journal of Pulp and Paper Science|
|Publication status||Published - 1 Jul 1999|