Recycled fibers for fluting production: The role of lignocellulosic micro/nanofibers of banana leaves

Recycling is becoming one of the main activities of the papermaking industry to palliate the consumption of natural resources. However, with the recycling process, the fibers experience structural damages due to the hornification phenomena and the mechanical refining. The present work aims to compare the effect of mechanical refining during recycling cycles, to recover the original mechanical properties of paper with the incorporation of lignocellulosic micro/nanofibers (LCMNF) from banana leaf residue. For that, industrial fluting paper was submitted to a recycling cycle and the effect of the increasing intensity of PFI-refining was compared versus the incorporation of LCMNF additions ranging from 1.5 to 4.5 wt%. In addition, with the objective of demonstrating that the proposed process could be plausible at a large scale, process water with high conductivity and charge density was used for comparison with tap water, usually used at laboratory scale. Results showed that the incorporation of 1.5 wt% of LCMNF was enough to recover the original properties of fluting paper (a breaking length value greater than 3443 m) with a low impact in pulp drainability (54 ºSR). At the same time, no structural damages were caused to the fibrous compounds, implying that the life span of paper products can be successfully increased. Higher dosages lead to papers with significantly improved mechanical properties, opening the opportunity to adopt environmental friendly strategies such as decreasing basis weight or, on the other hand, to reach new market niches by maintaining the basis weight.