Single-use hard plastics are all around us in the form of utensils, party decorations and food containers, to name a few examples. These items pile up in landfills, and even “biodegradable versions” stick around for months, requiring industrial composting systems to fully degrade. But now, new research reported in the journal ACS Sustainable Chemistry & Engineering has created a sturdy, lightweight material that disintegrates on-demand.
The new type of rigid material was designed using iso-malt, a sugar alcohol rather than a polymer. With iso-malt, bakers can create breathtaking, but brittle, structures for desserts, and then dissolve them away quickly in water. So, the researchers wanted to boost the sturdiness of iso-malt with natural additives to create a robust material that degrades on-demand. They heated iso-malt to a liquid-like state and mixed in either cellulose, cellulose and sawdust, or wood flour to produce three different materials.
Then, using commercial plastics manufacturing equipment, the materials were extruded into small pellets and molded into various objects, including balls, a dodecahedron, a chess piece and flower-shaped saucers. All of the tested additives doubled the strength of iso-malt, creating materials that were harder than common plastics including PET and PVC, but were still lightweight. In experiments, samples dissolved in water within minutes. Yet saucers made of the material and coated with a food grade shellac as well as cellulose acetate, withstood being immersed in water for up to seven days. However, once the saucers were broken and the coating cracked, they rapidly disintegrated in water.
The team also repeatedly crushed, dissolved and recycled both coated and uncoated objects into new ones that were still as strong as the original items. The researchers say that this new material could be used for food-service items and temporary décor, and then crushed and sprayed with water to fall apart. But even if such items were simply tossed into the trash or somehow got into the environment, the slightest crack in the coating would start their collapse into sugars and plant-based additives, which the researchers say would be good for the soil.