Lignocellulose nanofiber and starch for surface application on recycled linerboard

In a paper production line, starch is widely used for surface treatment and strengthening of linerboard at a size press. Also, the application of lignocellulose nanofibers (LCNFs) is growing because of its relatively low production energy demand, cost, and less hydrophilic nature in comparison to lignin-free nanofibers. Therefore, the addition of LCNFs to starch for paper surface treatment to reinforce the starch film and improve certain physical and mechanical properties of recycled linerboard was investigated in this work. Various LCNF/starch ratios were homogenized and then applied on the paperboard surface. The results revealed that a low mixing ratio of LCNF (5%) with starch improved the tensile index of the recycled paperboard, and at 50% LCNF content in the surface-treating material, film forming on the linerboard was observed in field emission-scanning electron microscopy images. In the case of 95% LCNF addition to starch, bending stiffness was significantly increased. Additionally, the viscosity of the sizing suspension was studied as a crucial parameter in the process and was found to increase significantly following the addition of LCNF.