Value-added composite bioproducts reinforced with regionally significant agricultural residues

Biocomposites are potentially sustainable alternatives to traditional plastics and composites for which recycling is challenging. We assess four agricultural residue fibers (AF) in biocomposites with poly-(hydroxybutyrate-co-hydroxyvalerate) (PHBV): (i) hollow stem wheat, (ii) solid stem wheat, and (iii) barley as regionally significant food crop residues compared to (iv) hemp residue as an industrially-relevant control. AF (0 wt.%, 10 wt.%, 20 wt.%, 30 wt.%) were compounded with PHBV using two compatibilization treatments: (i) a silane coupling agent vapor deposited at room temperature and (ii) PHBV grafted to the fibers using reactive extrusion (gPHBV). Flexural modulus and ultimate strength were used to evaluate the impact of fiber fraction and treatments. Modulus increased with increasing fiber fraction, with 30% treated hemp composites having the highest modulus and strength. Hollow stem wheat was most comparable to hemp. The mechanical properties of the different AF-composites occupy a similar application space, indicating potential for robust composite processing using AF.