In this study, citric acid modified cellulose nanocrystals (MCNC) and silica aerogel (SA) were used as reinforcing agents and added to polyvinyl alcohol (PVA) in different proportions to prepare composite films with excellent mechanical and barrier properties. After modification with citric acid, MCNC successfully contained ester bonds. SEM and FTIR results showed that MCNC and SA were uniformly dispersed in the PVA matrix and formed a compact structure. XRD results showed that there were physical interactions between the reinforcing agents and PVA, which improved the thermal stability of the film. Meanwhile, the composite film obtained good barrier properties after adding 0.5 % MCNC and 1.5 % SA. The carbon dioxide permeability decreased by 66.01 % and the oxygen permeability decreased by 69.46 % (23 °C, 50 % RH) and 40.14 % (38 °C, 90 % RH). The tensile strength increased to 43.79 MPa. Therefore, the composite film can be widely used in the packaging of food, medicine, etc.
Keywords: Cellulose nanocrystals; Mechanical properties; Polyvinyl alcohol; Silica aerogels; Thermal stability.
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