XPS imaging of surface diffusion of alkylketene dimer on paper surfaces

The alkylketene dimer (AKD) wax dispersion is introduced in the wet-end of a paper machine, and during drying it spreads and anchors to the fiber surface. Direct observation of the surface diffusion of the AKD wax at paper surfaces was obtained using X-ray photoelectron spectroscopy imaging technique. An AKD diffusion of approximately 400 μm was observed at a paper surface that was stored for 3 h at 80 °C. This gives a diffusion coefficient of approximately 10−11 m2 s−1. Storage for 1 week at room temperature also showed a remarkable spreading of AKD.