Researchers have developed a method of 3D printing thermal insulation using wheat straw.
Wheat straw is normally a waste product of modern agriculture, as it is typically burned after the wheat is harvested. That releases CO2 into the atmosphere, not a good thing to do. Other methods of disposal are expensive, such as plowing the straw back into the earth where it might provide some nutrients for the next crop.
Today’s typical fibreglass-style insulation is ultimately made from oil, a non-renewable resource. The researchers wondered whether it would be possible to create a new kind of sustainable and easily producible thermal insulation material using waste wheat straw.
The work was undertaken by Chi Zhou, PhD of the University of Buffalo, starting in 2022. Why attempt this experiment? Zhou explains:
“The superior properties come from wheat straw’s unique structure, its natural fibrous and porous composition, which enhances thermal insulation. Their unique properties, such as low thermal conductivity and low density, make them valuable for a wide range of applications, especially in building insulation.”
In addition, the wheat straw is more flame retardant than most other organic materials.
But how do you 3D print wheat straw? It doesn’t come in filament form on spools.
The researchers first formed the waste into pulp slurry, where the fibers bind together due to hydrogen bonding with the cellulose in the material. The paste can then be extruded into required shapes. However, they used a specialized extruder with a “slot-die” nozzle. This enabled a wide extrusion at a faster rate, and ensured proper flow through the system.
The system was used to print thermal insulation panels, which could then be installed in homes instead of fiberglass insulation.
There’s one more benefit to this approach, but it isn’t evident until much later. When homes are torn down, the insulation usually ends up in the local landfill. There the fiberglass will break down into microplastics that will pollute the environment. The wheat straw insulation, on the other hand, would simply decompose naturally and no longer leave any trace.
While this is still an experiment, I’m hoping that the process proves economical. If it is the same or less expensive than traditional insulation, it could catch on — and help us maintain our environment.
