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

One of the critical challenges in the fber-based packaging industry is to produce low-density paperboards with high functionality and atractive cost structure. In this study, we examine how control of the hierarchical fber swelling can be used to enhance bonding and generate a low-density fber 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 refning, this process causes the fbril aggregates to split and swell up massively. This efect was measured by a novel thermoporosimetry analysis method. The treated fbers have enhanced external fbrillation, fbrillar fnes and bonding potential. When mixed with relatively stif, unrefned fbers, a well-bonded sheet with lower density than a conventionally refned reference sheet was achieved. The results suggest that pulp fbers can be “nanoengineered” to enhance performance without the complications of producing and adding nanocellulose.