Preparation of hemp-based biocomposites and their potential industrial application

Biocomposites are an emerging field in plastic industry. The incorporation of agri-food waste in conventional or biobased polymer matrices allows the industry to lessen its carbon footprint, while producing recyclable plastic prod- ucts. In this work, hemp hurd, a byproduct of hemp fiber production process, was used as a filler to prepare novel compostable composites in two different loadings (22% and 32% w/w respectively). Waste hemp hurds were selected due to their abundance and the lack of derived high-value products. Three different polymers were used, namely poly[(tetramethyleneadipate)- co-(tetramethyleneterephthalate)] (PBAT) and poly(tetramethylene succinate) (PBS) as compostable polymers and a polyethylene elastomer for comparison. The bare polymers and prepared blends were then characterized for their struc- ture and morphology by XRD and FESEM, as well as for their wettability, ther- mal and mechanical properties (namely energy absorbed on impact and flexural modulus). Structural and morphological characterization unveiled the different interactions occurring between hemp and the polymer matrices, suggesting the major impact of the type of used polymer when compared with biomass loading percentages. Mechanical tests showed that both PBAT and PBS blends proper- ties are comparable to those of the pure polymers (i.e., in the case of PBAT the flexural modulus of the pure polymer was 82.2 MPa while the hemp-loaded blends stood at around 50 MPa, whereas all PBS polymers and blends were 220 MPa, with no statistical difference between samples). These biomaterials have also similar thermal properties with respect to the bare polymers, underlin- ing the promising potential as sustainable alternative to pure polymers.