Hydrophobisation of mechanical pulp fibres with sodium dodecyl sulphate functionalised layered double hydroxide particles

Hydrogen peroxide bleached spruce (Picea abies L.) made of thermo mechanical pulp (BTMP) fibres were modified with layered double hydroxides (LDH). The LDH particles were precipitated onto the BTMP fibre surfaces from aqueous solutions of urea and NaOH. The modified BTMP was further functionalised with sodium dodecyl sulphate (SDS) surfactant to produce pulp with hydrophobic character. The contact angle measurement with water on paper showed that the functionalisation with SDS was successful. The apparent contact angles varied in between the initial theta = 75 degrees of the reference pulp up to theta = 135 degrees of the SDS functionalised pulp. A hydrophobic surface was obtained already with 2.0 % weight to weight ratio of SDS in pulp suspension. A high affinity between the LDH particles and the BTMP fibres was found as well. The investigated fibre modification route offers a new feasible tool in fibre surface treatment.