CLEVELAND—"Biobased" and "biodegradable" are terms that are bandied about universally when discussing solutions to the proliferation of polymer waste, according to Ramani Narayan, distinguished professor at Michigan State University.
But both terms are useless unless people understand what they mean and how they work scientifically, Narayan told his audience in his keynote speech at the International Elastomer Conference in Cleveland Oct. 8.
"It is wrong, misleading and deceptive to use 'biodegradable' in an unqualified way," Narayan said. In fact, careless use of the term in advertising is forbidden by the Federal Trade Commission and the State of California. The latter fined Amazon $1.5 million for advertising bogus "biodegradable" products on its website, he said.
According to Narayan, "biobased" signifies whether the carbon content in any substance comes from organic sources, such as plants and agricultural sources, rather than fossil sources such as oil and coal.
"If the content is 100 years old or less, you can accurately measure its biobased content," he said. There is a value proposition with products made from plant biomass that does not exist with products made from oil or coal, he said.
But just because a product is biobased doesn't make it biodegradable, according to Narayan.
"'Biobased' addresses a product's origins, while 'biodegradable' addresses end-of-life issues," he said. "One does not equate to the other."
"Biodegradable" signifies whether micro-organisms can utilize the molecules of a substance as a food source, according to Narayan.
They do this by transporting the C-substrate inside the cell and converting it to carbon dioxide, he said. Even then, that leaves the question of whether the micro-organisms will consume the substance completely or leave a residue. The more residue they leave, obviously the less acceptable the level of biodegradability, Narayan said.