Mechanical and physical properties of expanded starch, reinforced by natural fibres

Biodegradable foams made from potato starch and natural fibres were obtained by extrusion. The effects of varying origins of these fibres on foam properties were studied, as well the relationships between their properties and the foam microstructure. The addition of fibres increased the expansion index and led to a significant reduction in water adsorption of starch foams, generally improving foam properties. The mechanical properties of the foams were affected by both relative humidity (RH) of storage and foam formulation. In general, as the RH increased, the foam strength decreased. The formulation presenting the best mechanical properties contained 10 wt% hemp fibre and had a maximal resistance of 4.14 MPa and a modulus of 228 MPa, corresponding to a more compact and dense microstructure.

► Biodegradable foams were produced by extrusion of raw materials. ► Functional properties (density, expansion, mechanical properties) were characterized. ► The presence of fibres affects the mechanical properties of the foam. ► The mechanical properties were affected by relative humidity of storage and foam formulation. ► The formulation containing starch and 10 wt% hemp fibres exhibited the best properties.