Influence of ZnO on the properties of dilute and semi-dilute cellulose-NaOH-water solutions
Résumé
The influence of ZnO as cellulose-8%NaOH-water solution stabilizer against gelation is studied. Cellulose intrinsic viscosity in 8%NaOH-water as a function of solution temperature is investigated in the presence and absence of ZnO. The addition of ZnO did not bring any improvement in terms of solvent thermodynamic quality. Non-dissolved ZnO particles were observed above 0.8-0.9% ZnO in 8%NaOH-water. Gelation of cellulose-8%NaOH solutions with and without ZnO are studied for various cellulose and ZnO concentrations (4-6% and 0-1.5%, respectively) in a wide range of temperatures (-5 °C to 50 °C). Gelation times were exponentially increasing with increasing ZnO concentration and with decreasing cellulose concentration and solution temperature. Gelation times of cellulose-NaOH-water-ZnO systems were found to follow a semi-empirical model correlating these three parameters. We suggest that ZnO is acting as water molecular "binder" stabilizing cellulose-NaOH-water solutions.
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