Nanoporous cellulose nanocomposite foams as high insulated food packaging materials

Abstract

• Nanocomposite foam-like materials were prepared based on cellulose/SM-MMT. • The presence of SM-MMT improved the insulation performance of cellulose matrix by reducing the cell sizes. • The dispersed SM-MMT particles cooperated on the improvement of thermal, mechanical and barrier properties of cellulose matrix. In this study, cellulose nanocomposite foams incorporated with surface-modified montmorillonite (SM-MMT) were developed using high shear homogenizer method which can substantially delaminate clay platelets. The goal of this study was to improve the properties of cellulose matrix as well as reducing the bubble sizes to prepare nanofoams in order to enhance mechanical and barrier properties, and thermal insulation performance. Several methods were used to characterize the prepared foam materials including scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermal conductivity, mechanical and barrier analysis. Raman spectroscopy was also used to evaluate structural differences between microcrystalline cellulose and nanocomposite foams. The results of thermal conductivity and morphology indicated that presence of SM-MMT improved thermal insulating properties due to reduction of average cell size. Thermal, mechanical and barrier properties were significantly enhanced for the nanocomposites filled with low content of SM-MMT compared to pure cellulose foam. The properties of these materials allow their use as a possible alternative to expanded polystyrene (EPS) foam trays for dry food packaging. Additional studies would be needed to improve the properties to use these materials with moist foods. The thermal conductivity values obtained for cellulose foams make them suitable to use for chilled chains.