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Tuning pulp properties with new wet-strength additives
- Jelka Feldhusen
- Itaconic acid, a dicarboxylic acid produced from citric acid or fermentation of sugars, is predicted to become a valuable bio-based chemical for the future, making it interesting for applications in cellulose based functional materials. The presentation will explain the tailored modification of Bleached Kraft Pulp (BKP) with itaconic derivatives followed by azetidinium salt conjugation. The reactions are performed through gas-phase reactions with the anhydride, or through high consistency mixing of anhydride with pulp, both gaining itaconic-BKP with increased fibre charge. For a better understanding of how the reaction occurs in the fibre network, nanocrystalline cellulose and glucose were used as model substrates. The conjugation of the Azetidinium salts to the itaconic-BKP was performed in heterogenous mixtures of the itaconic modified fibres in water. Through the modification with itaconic acid itself, the fibres already gain desired wet-strength properties, however further modification with azetidinium salts gain even more control and other possibilities of applications. Azetidinium salts, the reactive part of polyamidoamine-epichlorohydrin (PAE) wet-strength resins, were prepared by a two-step process from dialkylamines and epichlorohydrin, producing 3-Chloro-2-hydroxypropyl-N,N-dialkylamines which thereafter were ring-closed into the azetidinium salts. For the verification of successful grafting of itaconic acid/anhydride and azetidinium salts, solid state NMR and ATR-FTIR were used, alongside polyelectrolyte and potentiometric titrations for the assessment of fibre charge and degree of substitution.
