Farmers today are responsible for a small but growing share of the feedstocks used to make plastics.
Sustainability and degradability are driving interest in the issue, and were the topic of a conference about green plastics manufacturing held April 17-18 at the University of Massachusetts at Lowell.
``Society wants safer materials - and what better time is it to be doing what we are doing than the existing time?'' said John Warner, director of the Center for Green Chemistry in the Plastics Engineering Department at UMass.
Another UMass professor, Steve McCarthy, has worked with biodegradable polymers for 15 years and echoed Warner's perspective.
``It's something that people have always wanted, but it has taken that long for prices to come down and for the performance to come up to the level where the majority of people are believers,'' said McCarthy, director of the university's Biodegradable Polymer Research Center.
The two men were part of a contingent of about 100 academics, engineers, agricultural activists, manufacturers and students at the conference. The event covered topics concerning biopolymer synthesis and design, processing and manufacturing, and the global environmental footprint.
``We know perennial crops are our future. The grasses and trees are our next generation of feedstock. But we need markets, policy and infrastructures to change to support it,'' said Jim Kleinschmit, director of the Rural Communities program for the Institute for Agriculture and Trade Policy based in Minneapolis.
He said the 2007 U.S. farm bill being debated in Washington is not only important to the 2 million U.S. farmers - but also to taxpayers who pay for the subsidies and live with the consequences. He said developing sustainable materials means looking at the limits and impacts of feedstock, refining and end-of-line concerns, and making a transition to biomass sustainability.
Brenda Platt, co-director of the Institute for Local Self-Reliance in Washington, stressed the importance of keeping plastics out of landfills.
She pointed to bioplastics that are compostable as a way to reach zero waste. Platt also noted that proper education and improved labeling of corn-based plastics would aid in the recycling process.
Platt and Kleinschmit highlighted the ``Sustainable Bioplastic Guidelines,'' published by the Sustainable Biomaterials Collaborative, as a document of best practices that should be followed in the use of bioplastics.
Metabolix Inc. of Cambridge, Mass., which produces biodegradable plastics, serves as an example of what companies that embrace polyhydroxyalkanoate can achieve, according to professor McCarthy. In 12 years, the company went from a very small startup to a leader of change.
Metabolix sent three speakers to the event. The company is in the midst of developing commercial applications for corn-based PHA and is joining Archer Daniels Midland Co. of Decatur, Ill., to build a plant in Clinton, Iowa.
Corn-based PHA and polylactic acid, as well as cellulose-based materials, are some of the biopolymers on firms' agendas.
McCarthy said the change in materials eventually will change machinery.
``Initially they will seek to displace incumbent polymers and to do that, they will have to displace them on their own equipment. Once it is seen that they work, there will be new equipment evolving that will be able to process it more efficiently,'' he said.
Representatives from extruder makers Leistritz Corp. and Coperion Corp. responded.
``The twin-screw extrusion system doesn't need to be redesigned, only tweaked for success,'' said Leistritz General Manager Charlie Martin.
Operators working with PLA need to be aware it is a heat- and sheer-sensitive material.
Ed Beecher, process lab manager at Coperion, said the price of bioplastics has come down but doesn't have to match petroleum-based plastics to gain acceptance. He said PLA use was small compared with oil-based resins, but interest is growing.
The Plastics Institute of America Inc., a nonprofit education and research organization, and UMass sponsored the conference.