Enhancing the Oxygen Barrier Properties of Nanocellulose at High Humidity: Numerical and Experimental Assessment

Abstract

Films formed from cellulose nanofibrils (CNFs) are known to be good barrier materials against oxygen, but they lose this feature once placed in humid conditions. To tackle this issue, we applied an optimized pressing condition under elevated temperature to increase the films’ density and improve their barrier performance. Furthermore, a water barrier coating was employed on the surfaces to control the moisture uptake at high relative humidity (RH). Neat self-standing films of CNF with the basis weight of 70 g/m2 were made through a filtration technique and pressed for 1 hour at 130 °C. The resulting nanostructures were covered on both sides using a water-borne barrier layer. Hot-pressing resulted in a significant reduction in oxygen transmission rate (OTR) values, from 516.7 to 3.6 (cm3/(m2·day)) and to some degree, helped preserve the reduced oxygen transmission at high relative humidity. Introducing 35 g/m2 of latex coating layer on both sides limited the films’ swelling at 90% RH for about 4 h and maintained the OTR at the same level. A finite element model was used to predict the dynamic uptake of water into the systems. The model was found to over-predict the rate of water uptake for uncoated samples but gave the correct order of magnitude results for samples that were coated. The obtained data confirmed the positive effect of hot-pressing combined with coating to produce a film with low oxygen transmission rate and potential to maintain its oxygen barrier feature at high relative humidity.

Turning Recycled Cardboard Container-Derived Lignin-Containing Cellulose Nanofibrils into a Robust Gas Barrier UV-Shielding Film

“…Moreover, PAE-treated films showed 27% lower EMC than the alum-treated samples, resulting in a more moisture sorption in the latter one. The higher moisture sorption can cause swelling of the fibrils disrupting the chain linkage and working as a medium for oxygen dissolution, facilitating the oxygen transfer. , Aside from the crosslinker type, the concentration of the alum/PAE bath significantly controlled the OP values. The concentration of the alum/PAE bath did not exhibit a linear relationship with the OP values.…”

Sustainable, self-cleaning, transparent, and moisture/oxygen-barrier coating films for food packaging

“…54,55 The oxygen permeability is not only determined by the nature of the coating materials, but also depends on the relative humidity (RH). 56 As a representative, the OTR dependence of the GB40 film on RH was investigated and is presented in Fig. S5 and Table S3.…”

Preparation and benchmarking of novel cellulose nanopaper

“…Table 3 shows that the plateau oxygen permeability of 1.24 cc µm/m 2 day kPa is one to three orders of magnitude lower than the common petroleum-derived polymers, except for EVOH. However, the oxygen barrier properties of nanopaper samples are often compromised under high humidity conditions which may explain the observed order of magnitude difference in the oxygen permeability results (Tayeb et al 2020 ). This contrasts with the water vapour permeability data in Table 4 where the plateau water vapour permeability of 3 × 10 –11 g/m.s Pa is two to three orders of magnitude higher.…”