Polyhydroxybutyrate/hemp biocomposite: tuning performances by process and compatibilisation

A fully bio-sourced and biodegradable composite material has been developed based on polyhydroxybutyrate and hemp fibres (20 wt% content). Improvements of the final performances of composite materials were shown to depend highly on the filler dispersion state and on the polar filler/apolar matrix interface. Those two parameters were tuned by playing around with the processing conditions (screw profile and speed) and the formulation (possible recourse to a green compatibiliser). The so-prepared biocomposites exhibited homogeneous structures, a controlled matrix–fibre interface and suitable thermal properties. Even if the materials also suffered some matrix degradation from identified sources, their mechanical properties were maintained and their water vapour sensitivity could be tuned by the processing conditions and formulation. The strong nucleating effect provided by the fibres has been highlighted, and a clear fibre–matrix load transfer confirmed the effectiveness of the prepared compatibiliser. Concerning the end of life, the high biodegradability of the fully bio-based composites in compost was also confirmed.