There are several different meanings to the term “bioplastics” being used today including medical plastics, natural polymers (like collagen), biodegradable plastics, oxo-degradable plastics and plastics from renewable sources.
In North America the latter is the primary designation, whereas in Europe the compostable and biodegradable materials have been more highly rated.
Each continent has set up its own standards and labelling protocols to aid purchasing managers and consumers in understanding what they are buying into. A market study in 2009 by Utrecht University in Holland predicted a bio-based plastics market size of 2.3 million tonnes in 2013 including conventional polymers from renewable sources.
In the first half of 2011, Applied Market Information LLC organized an international conference in Miami, Florida for the plastics industry to discuss practical aspects of bioplastics use and disposal, Bioplastics Compounding and Processing 2011.
The program covered primarily the relatively new plastics derived from plants including PLA and polyesters like PHA, and suitable additives and processing technology, as parameters and performance have to be tailored for different applications.
The technology to produce these materials has been available for several decades, but polymer supplies have been limited and relatively expensive. With the current focus on sustainability coupled with the rise in oil prices and increasing output, there is now greater market interest.
Professor Ramani Narayan of Michigan State University is the leading US academic in this field with research on renewable carbon content, life cycle analysis (LCA), processing and degradability. He is the Scientific Chair of the Biodegradable Products Institute (BPI) in North America, and chairs the American standards ASTM committee on Environmentally Degradable Plastics and Biobased Products.
Narayan gave the keynote address at the Bioplastics Compounding and Processing conference and outlined the value proposition for plant-origin plastics: the reduction in CO2 emissions, renewable feedstocks, and the economic development of rural areas.
Crops and residues can be processed to give monomers, sugars and oils, which can be converted to PLA, PHA or conventional ethylene/propylene (via ethanol).
It is the carbon origin that gives environmental value, not the production processes. It takes more than a million years to fix the carbon in fossil sources like oil, whereas it only takes 1-10 years to fix carbon in plants, thus giving a sustainable carbon cycle. The current buzz in the industry is in the use of algae as sources, because of the rapid growth and short life cycle.
The standard ASTM D6866 gives test methods for determining the biobased carbon content of a product using radiocarbon analysis. The principle behind this is the carbon cycle where radiation generates C14 from N14 in the atmosphere.
This C14 is present in plants, but has decayed to C12 in fossil fuels, so by determining the C14 content of a polymer the percentage of renewable origin can be measured. This is the primary standard in use in the USA today.
The US government has set up a Biopreferred procurement system and the US Department of Agriculture (USDA) has a “Certified Biobased Product” labeling program to guide purchasing.
Biodegradability is also subject to standards and testing. The time frame should be short and the polymer should be completely used up by microorganisms to qualify.