Scientists at the University of Massachusetts Amherst have developed a sawdust-based foam that could offer a renewable alternative to expanded polystyrene (EPS) used in protective packaging applications, according to research published in ACS Applied Polymer Materials.
The prototype material is produced from wood waste, including both processed wood powder and unprocessed sawmill residues, combined with cellulose-based binders and cross-linking agents. The mixture is moulded, frozen and freeze-dried before undergoing a final heat treatment to create lightweight foam structures.
Depending on the cellulose binder selected, the resulting material can be tailored for different performance requirements. Foams made with carboxymethyl cellulose exhibited greater stiffness than conventional polystyrene, while hydroxypropyl cellulose produced a softer, more flexible structure. According to the researchers, some formulations achieved mechanical strength and impact resistance comparable to polystyrene foams commonly used for protective packaging.
A beeswax coating was also found to improve resistance to moisture under humid conditions, while laboratory testing showed the cross-linked foams could absorb and release water without dissolving in acetone, unlike conventional polystyrene.
“PS and related foams are highly engineered materials developed over many decades. The initial driver for this work was in packaging foams, which are used in abundance to protect materials in transit,” said Todd Emrick, professor at the University of Massachusetts Amherst and corresponding author of the study.
“Since our initial assessment of mechanical properties appears promising, such sawdust-based foams may be examined further in all sorts of applications. For packaging applications, I don’t see any limitations at the moment. The material could potentially be used for packaging for electronic materials, consumable goods, food, as well as chemicals and biologics.”
The researchers note that the work remains at an early stage, with long-term durability yet to be fully assessed. However, initial testing suggests the material maintains its performance over periods ranging from weeks to several months, making it potentially suitable for transport and storage conditions.
“We haven’t done a long-term stability study yet. 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,” Emrick said.
“This is new and early-stage research; it’s difficult to say anything definitive. However, seeing that we were able to replicate some of its properties with foams produced from waste products, in this case, sawdust waste, I would think that the prospects are good for developing competitive materials with respect to performance and cost.”
The research comes as regulatory pressure continues to reduce the use of expanded polystyrene packaging worldwide. Several US states have introduced restrictions on single-use EPS foodservice products, while countries including Georgia and Ghana have announced bans covering various expanded polystyrene packaging items.
If further developed for commercial production, the sawdust-based foams could provide packaging manufacturers with a bio-based alternative for protective inserts, loose-fill packaging and other cushioning applications currently dominated by fossil fuel-derived foams.
