Melt processability, characterization, and antibacterial activity of compression-molded green composite sheets made of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) reinforced with coconut fibers impregnated with oregano essential oil

New packaging materials based on green composite sheets consisting of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and coconut fibers (CFs) were obtained by twin-screw extrusion (TSE) followed by compression molding. The effect of varying the CF weight content, i.e. 1, 3, 5, and 10wt.-%, and the screw speed during melt processing, i.e. 75, 150, and 225rpm, on both the aspect ratio and dispersion of the fibers was analyzed and related to the properties of the compression-molded sheets. Finally, the CFs were impregnated with oregano essential oil (OEO) by an innovative spray coating methodology and then incorporated into PHBV at the optimal processing conditions. The functionalized green composite sheets presented bacteriostatic effect against Staphylococcus aureus from fiber contents as low as 3wt.-%. Therefore, the here-prepared CFs can be successfully applied as natural vehicles to entrap extracts and develop green composites of high interest in active food packaging to provide protection and shelf life extension.This research was funded by the EU H2020 project YPACK (reference number 773872), the Spanish Ministry of Economy and Competitiveness (MINECO) project AGL2015-63855-C2-1-R, the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684), and the BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund (ERDF) under the scope of Norte2020 – Programa Operacional Regional do Norte. Prof. Sergio Torres-Giner wants to thank the European Cooperation in Science and Technology (COST) Action FP1405, ActInPak, for financial support during his Short Term Scientific Mission (STSM) at the University of Minho.