No abstract

According to the European Bioplastics association, in 2017, the so-called bioplastics represented only 2.06 million tons of the 320 million tons of plastics produced annually [1]. The global production capacity is expected to increase up to 2.62 million tons in 2023. This growth is pushed by the demand of more sophisticated biopolymers, new applications and products. From packaging, agriculture, consumer electronics, textile to automotive, bioplastics are used in an increasing number of applications. In fact, biopolymers offer a number of additional advantages if compared to conventional plastics, such as a reduced carbon footprint and additional waste management options. Among bio-based and biodegradable plastics, polylactic acid (PLA) is one of the most interesting ones due to their good mechanical properties, good workability, excellent barrier properties. Therefore, it is a good candidate for the replacement of polystyrene (PS), polypropylene (PP), and acrylonitrile butadiene styrene (ABS) in many applications. However, PLA presents some weak points mainly represented by its low ductility, poor toughness, low glass transition temperature, high sensitivity to moisture and relatively low gas barrier, that limit its use in packaging applications [2, 3]. Indeed, the main

No abstract

We discuss gas barrier mechanisms in biopolymer nanocomposite in which fillers of different natures and concentrations are added. The kinetics of gas transport is studied by gas phase permeation techniques and free volumes are analyzed by positron annihilation lifetime spectroscopy. Gas barrier properties of two biopolymer nanocomposite films are presented in relation to their free volume. The first film is poly(3-hydroxybutyrate-co-3hydroxyhexanoate) (PHBH) containing 0.25 wt% of graphene oxide (GO) filler nanoparticles. The second film is poly(lactic acid) (PLA) in which cellulose nanofibrils have been dispersed with content from 4.1 to 12.4 vol.%. It is shown that in both biopolymer films the filler addition improves their gas barrier properties but with different mechanism.