GELATION OF CRYSTALLINE NANOCELLULOSE IN THE PRESENCE OF HYDROXYETHYL CELLULOSE

In this work, hydroxyethyl cellulose (HEC) was used to induce gelation of electrosterically stabilized cellulose nanocrystal (ECNC) and common cellulose nanocrystal (CNC) suspensions. The main goals were to shift the gelation point to low concentrations of nanoparticles and clarify the role of interactions between ECNCs in contrast to CNCs. The rheological properties of CNC suspensions were investigated in the presence of HEC with or without CaCl2 while ECNC suspensions would be only mixed with HEC since the addition of salt would not alter the viscoelastic properties of the whole system. The structure build-up kinetics as well as the viscoelastic properties of the suspensions were compared. CaCl2 was used to induce gelation of CNC suspensions at a solid content as low as 0.2g/g in the presence of HEC. ECNC suspensions were less sensitive to HEC since the best result obtained for inducing gelation was achieved at a concentration of 4g/g. All the results presented are explained by the adsorption of HEC on the nanoparticles, which was determined by viscometry. High adsorption level of HEC chains imparted CNCs better colloidal stability in the presence of CaCl2 as compared to pristine CNCs, whereas it did not affect the ECNC colloidal stability.