Fibers pre-treatments with sodium silicate affect the properties of suspensions, films, and quality index of cellulose micro/nanofibrils

Abstract

The characteristics of cellulose micro/nanofibrils (MFC/CNF) can be improved with pre-treatments of the original fibers. The present work is proposed to study pre-treatment with sodium silicate (Na2SiO3) on bleached fibers of Eucalyptus sp. (EUC) and Pinus sp. (PIN) and its effects on the quality index of MFC/CNF. Particle homogeneity, turbidity, and microstructure of the suspensions were evaluated. Similarly, the physical-mechanical, and barrier properties of the films were studied. With the results obtained for suspensions and films, the quality index (QI) was MFC/CNF calculated. The smallest particle dimension was observed for MFC/CNF of Pinus sp. with 10 % of Na2SiO3, as well as the lowest turbidity (∼350 NTU) was obtained for MFC/CNF of Pinus sp. with 5 % of Na2SiO3. The pre-treatments reduced the transparency of the films by ∼25 % for EUC and ∼20 % for PIN. The films presented a suitable barrier to UVC radiation, water vapor, and oil. The tensile strength of EUC and PIN films was increased by 20 % using 10 % of Na2SiO3. The same concentration of Na2SiO3 provided QI 70 for EUC MFC/CNF. The Na2SiO3 was efficient to obtain the MFC/CNF with interesting properties and suitable to generate films with parameters required for packaging.