Time-triggered calcium ion bridging in preparation of films of oxidized microfibrillated cellulose and pulp

Publication date: Available online 18 April 2019Source: Carbohydrate PolymersAuthor(s): Pegah Khanjani, Matti Ristolainen, Harri Kosonen, Pasi Virtanen, Sara Ceccherini, Thaddeus Maloney, Tapani VuorinenAbstractOne of the main trends in developing bio-based materials is to improve their mechanical and physical properties using MFC derived from sustainable natural sources and compatible low-cost chemicals. The strength of anionic MFC based materials can be increased with addition of multivalent cations. However, direct mixing of solutions of multivalent cations with oxidized MFC may result in immediate, uncontrollable fibril aggregation and flock formation. The aim of this study was to design a method where Ca2+ ions liberate from solid CaCO3 particles on bleached hardwood (birch) kraft pulp, which was mixed with oxidized MFC and crosslink it to tailor the mechanical properties of the dried structure. In few minutes after adding acetic anhydride, pH of the wet film dropped from 7.3 to 4.8 through liberation of acetic acid and CaCO3 particles solubilized releasing Ca2+. The novel method could be applied on industrial scale for improving the performance of packaging materials.
Source: Carbohydrate Polymers - Category: Biomedical Science Source Type: research