Technological watch

There is currently great interest in biodegradable alternatives for packaging and agricultural applications. The most viable biodegradable alternative, poly (butylene adipate-co-terephthalate) (PBAT), has poor resistance to water vapor and oxygen permeation and tends to degrade rapidly under solar exposure. Herein, we report a preparation of PBAT nanocomposite films with aligned graphene nanosheets both in and on the films by combining two techniques, biaxial orientation and rod scarping. The composite films with a graphene content of 0.48 vol% exhibited 80% decrease of water vapor permeability and over 99% decrease of oxygen permeability, approaching values of 1.0 × 10?11 g m m?2·Pa?1 s?1 and 6.2 × 10?16 cm3 cm cm?2·Pa?1 s?1. These values are respectively comparable to and even lower than the reported 9.9 × 10?12 g m m?2·Pa?1 s?1 and 8.0 × 10?15 cm3 cm cm?2·Pa?1 s?1 for polyethylene films. After a 200 h aging, the composite films still possessed a fracture strength of 47.3 MPa and an elongation at break of 167%, in contrast to a complete fragmentation of pure PBAT. We believe that the controlled incorporation of aligned graphene nanosheets to biodegradable polymers could become an important strategy to develop sustainable packaging and agricultural films.