Performance comparison of coatings based on cellulose nanocrystals and microfibrillated cellulose for food packaging

This article aimed at comparing gas barrier performance of plastic films coated with both cellulose nanocrystals (CNCs) and microfibrillated cellulose (MFC) obtained from cotton linters. CNCs were chemically isolated by ammonium persulfate (APS) hydrolysis, while the MFC was obtained mechanically either by APS-assisted pretreatment (MFCaps) or without pretreatment (MFC). Initially, mechanical tests of the three samples were performed and their properties were characterized by dynamic light scattering, TEM, FTIR, TGA and WAXS. Subsequently, coated PET films were characterized by water contact angle, transparency and opacity evaluation following by water vapor and oxygen transmission rates assessment performed at 25 °C/ 90% RH and 25 °C/ [0%–80% RH] respectively. Finally, oxygen diffusion and solubility coefficients were calculated by using half-time method. The findings showed that, coated films based on MFCaps display a much better oxygen barrier under higher RH and a higher level of residue when submitted to 700 °C degradation compared to CNCs.