"Biopolymer Foams Composed of Sawdust: Fabrication and Structural Integrity" ACS Applied Polymer Materials
Polystyrene - common in packing peanuts and box inserts - is manufactured from fossil fuels. To develop a sustainable alternative, researchers reporting in ACS Applied Polymer Materials tested an unconventional starting material: sawdust. Their prototype foams incorporated cellulose binders and other additives to form rigid or flexible materials, and some versions matched polystyrene's strength and impact resistance. A simple beeswax coating made them water-resistant, producing biobased foams with potential for packaging and building materials.
Adapted from ACS Applied Polymer Materials 2026, DOI: 10.1021/acsapm.6c00854
"It can be exciting to use waste products as a starting point for materials fabrication, rather than a chemical catalog," says Todd Emrick, the corresponding author of the study. He adds that the first author of the paper, Isha Farook, drove to nearby farms and sawmills asking if the research team could have their sawdust waste. Both researchers were pleased and surprised that, once it was dried, this waste sawdust created well-performing foams.
In the lab, Emrick, Farook and colleagues blended sawdust (either fine processed wood powder or coarse unprocessed mill waste) with different combinations of cellulose binders and cross-linking ingredients. Then the researchers poured the mixtures into molds, froze them, and freeze-dried the foams to remove all the moisture. A final heat-drying step activated the cross-linked networks.
The prototype foams' properties varied depending on the cellulose binders: Carbomethyl cellulose versions were stiffer than polystyrene, and hydroxypropyl cellulose produced a softer material. Yet the researchers observed minimal differences between foams made with processed versus unprocessed sawdust.
Todd Emerick
Stability tests showed that the biobased foams containing cross-linking ingredients absorbed and released water while resisting dissolution in acetone, unlike polystyrene. Some foam samples were also coated in beeswax. The coating improved the water resistance when exposed to high humidity and did not impact the material's mechanical properties.
"We haven't done a long-term stability study yet," says Emrick. "But in the weeks-to-months time frame, the liquid stability appears to be excellent, which is a useful feature during shipping in case of leakage or spills, or simply for production and storage under different environmental conditions."
Finally, the researchers conducted impact tests with a 10-pound (4.5-kilogram) weight and observed that the biopolymer foams dispersed energy better, bouncing the weight 21% less distance than polystyrene of a similar thickness. These results suggest that the sawdust-based foams are robust enough for packaging applications where polystyrene is currently being used.
"The initial driver for this work was in packaging foams, which are used in abundance to protect materials in transit," says Emrick. "Because our initial assessment of mechanical properties appears promising, such sawdust-based foams may be examined further in all sorts of applications - including construction materials and high-end packaging for consumer electronics, where lightweight and protective packaging is essential."
The authors thank Hadley Millworks for providing the waste sawdust and acknowledge funding from the U.S. Department of Energy.
