Résumé
Polyhydroxyalkanoates (PHAs) are a class of fully biodegradable polyesters produced by microbialcultures. Because of their similarity to PE and PP and their high barrier properties, short-chain-lengthPHA (scl-PHA) such as poly-3-hydroxybutyrate homopolymer (P3HB) and poly-3-hydroxybutyrate-co-3-valerate copolymers (P3HBV) are the best candidates to replace fossil-based plastic in packagingsystems. Despite these advantages, large-scale diffusion has been limited by their high crystallinity,brittleness, melting point, and sensitivity to thermal degradation that negatively affect processability.A possible solution for scl-PHAs processing issue could be PHBV copolymers production with high3HV content to decrease melting point, glass transition temperature and crystallinity, leading to anincrease of the ductility of materials. However, higher 3HV could induce difficulties in theprocessability of self-supported films with in particular a slow crystallization rate, not suitable forthermoplastic applications. In order to tackle these problems, the effect of three different factors onprocessability and final properties were investigated: 3HV units’ content (3, 18 and 28 mol% of 3HV),the addition of 0.5, 1 and 2 wt% Boron Nitride (BN) as nucleating agent to increase crystallization rateand the addition of 5 wt% medium-chain-length-PHA (mcl-PHA) to improve mechanical propertiesand especially the ductility. All PHBV copolymers and their compounds with BN or mcl-PHA wereprepared through a twin-screw extrusion and compression moulding processes to give 100 μm thickfilms. PHBV formulations were characterised on a macro- and microscopic scale, i.e. thermal (TGA,DSC), mechanical and barrier properties. The results from characterization showed an improvementin ductility and thermal stability when mcl-PHA is added, while the addition of BN leads to theobtention of a homogenous structure, a toughened material and, in both cases, no change inpermeability