Eucalyptus wood nanofibrils as reinforcement of carrageenan and starch biopolymers for improvement of physical properties

Abstract

In tropical countries there are innumerous options of biodegradable polymers and lignocellulosic sources to produce green nanocomposites. The main drawback of carrageenan and starch application for packaging is their poor strength in high moisture conditions. However, blending and addition of cellulose nanofibrils may overcome the limitation. This investigation aimed to compare the physical strength of starch and carrageenan films, and to determine the best blending proportion of these biopolymers. In addition, a recommended load of eucalyptus cellulose nanofibrils, to produce nanocomposites with improved physical strength, was investigated. Carrageenan replaced starch at proportions 100, 80, 50, 20 and 0%. Cellulose nanofibrils were produced from eucalyptus sawdust and added to the films at 10, 20 and 30% loads. Carrageenan is more hydrophilic than starch, hence it should be applied up to 20% in blends. The increase of nanofibrils from 10 to 30% decreased water solubility and absorption, while density increased. A 10% load of nanofibrils was enough to decrease water vapor permeability. The physical strength of carrageenan for packaging may be improved by blending with starch and adding 30% of cellulose nanofibrils.