Using Biomass Particles and Biopolymers to Control the Mechanical Properties and Biodegradability of Renewable Foams

Polymeric foams are widely used in packaging, raising environmental concerns due to improper disposal and reliance on non-renewable feedstocks, prompting the development of renewable and biodegradable alternatives. Our study introduces renewable foam composites of unrefined biomass particles (sugarcane bagasse (SB) and eucalyptus waste (EW)) and biopolymers (starch (S) and pectin (P)). The foams were prepared by foam-forming, combining the components in water and incorporating air bubbles with mechanical stirring. The aqueous foams were then oven-dried, yielding low-density materials (0.13–0.19 g·cm–3), with SB foams displaying smaller pores (∼800 μm) than EW foams (∼1000 μm). The compressive strengths were comparable to those of rigid polymeric foams (0.08–0.27 MPa) and were dependent on foam composition. Respirometry confirmed the biodegradability of the foams, with rates governed by the biopolymer: starch-based foams biodegraded faster (0.25 and 0.23 d–1 for SB + S and EW + S) than pectin-based foams. The biodegradation kinetics were also influenced by the particles, as EW foams had longer lag times than SB foams. FTIR confirmed starch breakdown and increased water interactions after biodegradation. The findings show that combining raw biomass with biopolymers provides a green approach to controlling the mechanical properties and biodegradability of renewable foams designed for packaging applications.