Production of low-density and high-strength paperboards by controlled micro-nano fibrillation of fibers

Abstract

One of the critical challenges in the fiber-based packaging industry is to produce low-density paperboards with high functionality and attractive cost structure. In this study, we examine how control of the hierarchical fiber swelling can be used to enhance bonding and generate a low-density fiber network with excellent strength properties. Here, the osmotic pressure inside the cell wall is increased by adding phosphate groups with a deep eutectic solvent (DES) functional drying method. Together with mechanical refining, this process causes the fibril aggregates to split and swell up massively. This effect was measured by a novel thermoporosimetry analysis method. The treated fibers have enhanced external fibrillation, fibrillar fines and bonding potential. When mixed with relatively stiff, unrefined fibers, a well-bonded sheet with lower density than a conventionally refined reference sheet was achieved. The results suggest that pulp fibers can be “nanoengineered” to enhance performance without the complications of producing and adding nanocellulose.