Properties of Micro- and Nano-Reinforced Biopolymers for Food Applications

Abstract

Food packaging implies a significant consumption of different materials, of which plastics are the second most widely used. So, the development of biopolymers for food packaging applications is critically important. Although several biopolymers are available for different applications, they have some drawbacks and their functional properties need to be adapted for food packaging requirements. The incorporation of micro- and nano-fillers into the biopolymer matrix has proven to be an alternative means of improving their mechanical and barrier properties. In composites, the polymer forms the continuous matrix while the dispersed filler phase helps to positively modify the functional characteristics of the material. Different kinds of fillers have been used which modify the material characteristics as a function of their content and filler-matrix interactions. The particle size and shape, the amount and distribution and the chemical nature of the fillers are key factors in the final properties of the composite. In general, thermomechanical processes with high shearing forces and temperatures for the required time are needed to guarantee the convenient dispersion of the filler within the polymer matrix. In this chapter, the different kinds of fillers used in biopolymer composites have been summarized. The relevant surface properties and the changes induced by fillers on the mechanical, barrier and thermal properties of micro- and nano-composites have been discussed, with emphasis on food packaging applications. The processing techniques, formulation and final structure of materials have also been reviewed, as well as the influence of the fillers on the biodegradation behaviour of composites.