Poly(vinyl alcohol)/Carboxymethyl Cellulose/Cellulose nanofibrils nanocomposite as coating for food packaging paper

Cellulose nanofibrils (CNF) can be modified to be used as a coating on food paper packaging. Previous research on PVA/CNF composites showed a low viscosity, which impacted their performance on the coating paper process. To overcome this problem, a thickening agent, such as carboxymethyl cellulose (CMC), is needed. In this work, the effect of CMC on PVA/CMC/CNF nanocomposites was investigated by varying the concentrations of CMC with PVA/CMC and CNF ratio of 80:20 and 90:10. The nanocomposites were characterized by their physical and tensile properties which could affect their coating performance. Moreover, the coating process was conducted on paper and the performances of the coated paper were studied. The results showed that the increase in CMC concentration led to an increasing viscosity and good zeta potential, suggesting good dispersion. Moreover, the addition of CMC improved the tensile properties of PVA/CMC/CNF nanocomposites. However, SEM analysis of PVA/CMC-1:CNF (80:20) revealed the occurrence of agglomeration which might influence the performance of the coated paper. Interestingly, PVA/CMC-1:CNF (80:20) had an excellent water resistance, with the lowest Cobb₆₀. Moreover, the addition of CMC 1 wt% increased WVTR, which remained lower than the blank sample. Meanwhile, PVA/CMC-2:CNF (80:20) demonstrated the best performance in the oil absorption and tearing resistance test. In summary, the addition of CMC can effectively improve the physical and tensile properties of the PVA/CMC/CNF, as well as the barrier properties and tear strength of the PVA/CMC/CNF coated paper. The results demonstrate the potency of this material as a coating for food packaging paper.