Effect of micro- and nanofibrillated cellulose on the drying shrinkage, extensibility, and strength of fibre networks

Elongation is an important property of many packaging board and paper grades. Paper with high extensibility could provide an alternative for oil-based packaging materials. Micro- (CMF) and nanofibrillated (CNF) cellulose are known to increase the strength of a paper, but their effect on the drying shrinkage and elongation is not well-studied. In this work, paper was reinforced with fibrillated material. Added fibrillated material increased the drying shrinkage, which was generally proportional to the increase of paper elongation before breakage. Results differed depending on the fibrillated material and how it was added to paper (wet-end addition or spray application). The papers were dried unrestrained in order to achieve the highest elongation potential for the paper. Spray application of CMF increased elongation by 13%, while wet-end additions increased elongation by 20% and also strength by 10%, but only with high dosages. Spray application of oxidized-CNF improved elongation by 33%, while wet-end applications increased only strength by 20%. Thus, boosting the drying shrinkage with fibrillated cellulose is one potential way to increase elongation and 3D formability of paper.