Microplastics have become one of the greatest environmental challenges worldwide. To turn this dramatic damage around, EU regulators now want to ensure that plastic itself is fully recyclable or biodegradable. The aim of the present work is to develop a biobased and biodegradable biocomposite based on commercial polyhydroxyalkanoates (PHAs) and nanoclays, with the objective of achieving a reduction of rancid odour while avoiding any loss in thermomechanical properties, thus tackling two key disadvantages of PHAs. This research aims at completely characterising the structural, thermal and mechanical behaviour of the formulations developed, understanding the compatibility mechanisms in order to be able to assess the best commercial combinations for industrial applications in the packaging and automotive sectors. We report the development of nine nanobiocomposite materials based on three types of commercial PHA matrices: a linear poly(3-hydroxybutyrate) (P3HB); two copolymers based on poly(3-hydroxybutyrate)-co-poly(4-hydroxybutyrate) (P3HB-co-P4HB); and nanoclays, which represent a different polar behaviour. Dispersion achieved is highly relevant compared with literature results. Our findings show impressive mechanical enhancements, in particular for P3HB reinforced with sepiolite modified via aminosilanes.

We report a new strategy to obtain high performance polymer-grafted multi-walled carbon nanotubes (MWCNTs). Chlorophenyl-functionalized MWCNTs, obtained through the in situ generation and reaction of diazonium compounds, were subjected to polymerization in the presence of Na₂S and 1,4-dichlorobenzene in order to yield MWCNTs covalently functionalized with poly(p-phenylene sulfide) (PPS) oligomers. The MWCNT functionalization and the PPS oligomeric chain growth can be controlled throughout accessible experimental variables, including the possibility to carry out the whole process in a one-pot reaction. This represents an efficient and facile route to develop covalently grafted MWCNTs beyond those reported so far for the same polymer. These materials are promising fillers for the production of high performance PPS-based composite materials, due to the improvement of the filler–matrix compatibility. The manufacturing and characterization of some test samples show that oligomer-grafted MWCNTs induce the suppression of the intrinsic confinement effect imposed by the nanofiller, as for the observation of an increase in the PPS crystallinity. An outstanding increase in the PPS thermal stability and mechanical properties is also observed, as compared to bare MWCNTs, while leaving the electrical properties unharmed.