Researchers at the University of Washington have mixed coffee grounds, mushroom spores, and mycelium to 3D-print a ‘compostable’ packaging material said to perform similarly to polystyrene dunnage.
Doctoral student Danli Luo observed that coffee can be used to grow fungus, which then forms a mycelial ‘skin’ layer before it sprouts into mushrooms. This skin can bind, fuse, and weld separate components together – and to create a water-resistant, durable yet lightweight material.
Luo led a team of researchers at the University of Washington to mix used coffee grounds with Reishi mushroom spores, xanthan gum – a polysaccharide often used as a thickening agent, stabilizer, or emulsifier – brown rice flour, and water. This forms a ‘Mycofluid’ paste that can be used to print 3D objects, including items of packaging.
When inoculated with the mushroom spores that form the mycelial skin, the coffee grounds can be formed into a material set to replace plastics, even in complex shapes. Separate pieces can be fused together with the mycelium to form one object, with the researchers producing packaging for a small glass, among other objects.
According to Techxplore, the dry material is closer to the density of cardboard or charcoal than Styrofoam, but offers a strength and durability comparable to polystyrene and expanded polystyrene (EPS) foam. It is said to be fully compostable, although this has not yet been tested.
While it is expected to be challenging to scale, since the Mycofluid is said to require uniform granularity in its coffee grounds, the team intends to experiment with other recycled materials that might form similar biopastes.
A new 3D printer head has also been designed by the university’s Machine Agency lab and built for the Jubilee 3D printer; this is said to hold up to a litre of paste.
The team’s full findings have been published in the peer-reviewed journal 3D Printing and Additive Manufacturing.
“We’re especially interested in creating systems for people like small business owners producing small-batch products—for example, small, delicate glassware that needs resilient packaging to ship,” Luo explained. “So we’ve been working on new material recipes that can replace things like Styrofoam with something more sustainable and that can be easily customized for small-scale production.
“We’re interested in expanding this to other bio-derived materials, such as other forms of food waste. We want to broadly support this kind of flexible development, not just to provide one solution to this major problem of plastic waste.”
A previous project from the University of Washington resulted in the development of new bioplastics said to break down at the same rate as a banana peel in a home compost bin. This was hoped to prevent microplastic pollution if the plastic escapes its recycling stream.
HUID also sought to cut down on the amount of wasted food and fossil plastics in household waste streams by converting onion skins into a home-compostable packaging material. By extracting cellulose from skins and implementing it in a biopolymer blend, it creates a film with a comparable mechanical strength to traditional plastic solutions.
Earlier this year, Bournemouth University researchers unveiled a ‘self-repairing’ plastic designed to maintain most of its original strength after being damaged; the development, which is already used as a reinforcement agent to strengthen plastics, sought to cut down on single-use plastic waste.
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