ATP-Funded Green Process Technologies - NIST Advanced ...

PROJECT HISTORY
Polymers are commonly used in making industrial commodity products. Their
advantages include durability, strength, low weight, wide application range, ease of
processing, and the maturity of underlying manufacturing technologies. However,
polymers have the following disadvantages:
• They are traditionally made from petroleum-based feedstocks and thus accelerate
the depletion of finite petroleum resources. This also contributes to petroleum price
increases and price volatility.
• At the end of product life, post-consumer polymer waste streams lead to significant
disposal problems. In landfills, the natural degradation of petroleum-based
polymer wastes may require hundreds of years. Polymer recycling, as a way to
avoid land filling, has not kept up with consumption. Also, recycling may be
associated with new problems, such as the concentration of contaminants (Vink et
al., 2002).
With increasingly expensive and scarce petroleum resources and end-of-life waste
disposal problems, there has been long-standing commercial interest in developing
new biodegradable polymers made from renewable resources.
Polylactic acid—a biodegradable polymer made from renewable resources—is not a
new polymer. PLA has been used in soluble surgical sutures and in-vivo medical
applications. Manufacturing challenges have, however, limited PLA uses to smallbatch
production of high-cost specialty products.
In the mid-1980s, Cargill, Inc. launched a technology development effort for a new
industrial-scale process to make PLA resins from corn starch and also to improve PLA
functional properties. PLA resins were expected to compete on cost and performance
terms with petroleum-derived resins such as polyethylene terephthalate (PET).
Based on early development efforts, by the early 1990s Cargill developed a process
technology for manufacturing PLA on an industrial scale. Customer evaluations in
the food packaging and fiber sectors pointed to performance challenges in a number
of areas, including inadequate temperature resistance for storage, shipping, and use
with hot foods; long in-mold cycle times; inadequate toughness and barrier
properties; and insufficient knowledge about the controlled degradability at end-oflife
disposal.
Given the complexity of these technical challenges, in 1994 Cargill submitted a
proposal to ATP for cost sharing the “Development of Improved Functional
Properties in Renewable-Resource-Based Biodegradable Plastics.” The proposal
18 ATP-FUNDED GREEN PROCESS TECHNOLOGIES