In this study, the ability of natural hemp fibers (HF) to act as fillers in biodegradable biocomposites has been evaluated by mixing different concentrations of HF with commercially- available biodegradable polyesters, aiming at incorporating the maximum amount of HF to obtain a cost-effective new material in a sustainable approach. Blends of poly(hydroxy‑butyrate) (PHBV) and poly (butylene adipate-co-terephthalate) (PBAT) were used as polymeric matrix. HF were washed and ground before use. They were mainly composed of lignin (̴ 22 %) and carbohydrates (̴ 62–67 %) but a significant amount of proteins (̴ 8.77 %) was also detected. The polymer-HF composites were produced by melt-compounding using mild conditions and shaped as films by compression-molding to obtain test specimens used in the characterization of the biocomposites. The effect of HF loading on the final performance of the biocomposites was investigated. Interestingly, up of 40 % of HF could be incorporated as fillers into the PHBV-PBAT polymeric matrix. The incorporation of HF improved mechanical performance when compared to the polyester blends. In order to reduce its water sensitivity of the composites, food-grade beeswax or carnauba wax were incorporated within the polymeric matrix filled with HF, and the resulting biocomposites showed similar mechanical properties than their counterparts prepared without waxes but displayed significantly higher hydrophobicity.

The authors wish to thank the partial financial supporter to this project by the Coordination for the Improvement of Higher Education Personnel (CAPES) of Brazil. The authors wish to acknowledge funds from the grants PID2023-146557OB-C22 and CEX2021-001189-S funded by MCIN/AEI/ 10.13039/501100011033 and by “ERDF A way of making Europe”

Peer reviewed