Nanofibrillation of a Bleached Acacia Pulp by Grinding with Carboxymethylation Pretreatment

In this study,carboxymethylation,which introduces carboxyl groups to hydroxyl sites in pulp fibers,was used as a pretreatment before mechanical nanofibrillation.The carboxyl group content of the pulp fibers was greatly affected by the dosage of chloroacetic acid and the reaction temperature.During the following fibrillation process,it was found that pulp fibers with higher carboxyl group content exhibited higher water holding capacities and smaller dimensions.A more homogenous structure with a higher amount of individual fibrils was also observed in FE-SEM images of pulp fibers with high carboxyl group content.This can be explained by a high ionic group content in the fiber wall resulting in lower delamination resistance,making the fibrils easier to separate.Carboxymethylation pretreatment as a facilitator of fibrillation in cellulosic pulps is an efficient way to obtain cellulose nanofibrils and consequently decrease the energy consumption of the process.     

Improvement of filtration efficiency by fibre surface nanofibrillation

High-pressure water jets (hydroentanglement) were used to liberate a layer of nanofibres from the surface of flax fibres without severely damaging the main fibre body. The liberated nanofibres form interconnected networks that link the parent flax fibres together and strengthen the cohesion between the flax fibres, which improved the fabric abrasion resistance more than tenfold. The nanofibre networks also fill the macroscale voids between the parent fibres and between the yarns in the fabric structure, which led to a considerably improved fine particle filtration efficiency of the fabric by a factor of about five.