What do hemp, mushrooms, milk and straw have in common? They’re just a few of the things that have been used to create “green” composite materials, in which most or all of the usual petroleum by-products are replaced by more environmentally-friendly substances. Now, thanks to two separate studies, it looks like peat and beets can be added to that list.
In Finland, the VTT Technical Research Centre is exploring ways in which the top layer of naturally-growing peat can be incorporated into thermoplastics and pressed-fiber panels.
Peat is reportedly a promising material for such applications, as not only is it abundant, but it’s also inexpensive, water-resistant, biodegradable, and exhibits high impact strength and fire endurance. Additionally, not only do its fibers provide structural strength when added to a resin, but the finer peat material can also be added as a filler.
According to VTT, plastics containing peat can be processed using existing facilities and techniques, such as extrusion and injection molding. The researchers suggest that peat-based plastics and panels could be used in products relating to fields such as building construction, horticulture/agriculture, consumer goods, and biodegradable packaging.
Plant physiologist Arland Hotchkiss (right) adds sugar beet pulp and polylactic acid to an extruder to make the bioplastic strips that chemist LinShu Liu is inspecting
In America, meanwhile, scientists from the U.S. Department of Agriculture and Washington State University have collaborated to create a spongy biodegradable beet-based thermoplastic for use in disposable food containers.
The researchers started with beet pulp residue – tons of the stuff is already being generated annually, as part of the beet sugar extraction process. They mixed that pulp with polylactic acid (PLA), a biodegradable polymer which is itself made from plants, and is currently used in products such as pop bottles. When the mixture was extruded, the result was a composite material with mechanical properties similar to those of polystyrene and polypropylene.
According to the research team, which was led by Washington State’s Prof. Jinwen Zhang, the beet thermoplastic is “cost-competitive” with traditional petroleum-based materials.