Surface hydrophobization of pulp fibers in paper sheets via gas phase reactions

Hydrophobization of cellulosic materials and particularly paper products is a commonly used procedure to render papers more resistant water moisture. Here, we explore the hydrophobization unsized sheets via gas phase. We employed three different compounds, namely palmitoyl chloride (PCl), trifluoroacetic anhydride/acetic anhydride (TFAA/Ac2O)) hexamethyldisilazane (HMDS) which were vaporized allowed react with All routes yielded hydrophobic static contact angles far above 90° indicated formation covalent bonds. The PCl TFAA approach negatively impacted mechanical optical properties leading decrease in tensile strength yellowing sheets. HMDS modified did not exhibit any differences regarding relevant technological parameters (mechanical properties, porosity) compared non-modified XPS studies revealed that samples have rather low silicon content, pointing at submonolayers trimethylsilyl groups on fiber surfaces network. This was further investigated by penetration dynamic analysis using ultrasonication, whole network has been homogeneously silyl only very outer surface as for papers. yields possibility study influence hydrophobicity their without changing structural parameters.