Fluting medium strengthened by periodate–chlorite oxidized nanofibrillated celluloses

Abstract

Nanofibrillated cellulose (NFC) has potential for use as a strength-enhancing additive in paper and paperboard applications. In this work, the effect of NFC on the mechanical and air resistance properties of semichemical fluting handsheets with and without talc filler was studied. Nanofibrillated dicarboxyl acid cellulose (DCC NFC) was prepared using sequential periodate–chlorite oxidation followed by nanofibrillation using either microfluidization or high-pressure homogenization. The high-pressure homogenization led to uniformly sized nanofibrils whereas the microfluidized DCC NFC contained larger fibril bundles in addition to fine nanofibrils. Both DCC NFCs had a positive effect on the tensile strength (19–21 % improvement), flat crushing resistance (24–26 % improvement) and edgewise compression strength (22–32 % improvement) of the handsheets with 2 wt% dosage. Increased air resistance is frequently observed when NFC is used as a paper additive, but in this study the microfluidized DCC NFC decreased the air permeability properties of the handsheets only slightly while the homogenized DCC had a larger adverse influence. Use of talc filler as an additive in the fluting medium decreased its mechanical properties, but the addition of the DCC NFC compensated for the strength loss caused by the filler.