Final Report: Sustainable Polymeric NanocompositesEPA Contract Number: EPD06052
Title: Sustainable Polymeric Nanocomposites
Investigators: Hollingsworth, Laura O.
Small Business: PolyNew, Inc.
EPA Contact: Manager, SBIR Program
Project Period: March 1, 2006 through August 31, 2006
Project Amount: $69,469
RFA: Small Business Innovation Research (SBIR) - Phase I (2006) RFA Text | Recipients Lists
Research Category: Nanotechnology , SBIR - Nanotechnology , Small Business Innovation Research (SBIR)
Petroleum is finite in supply, and as more world economies develop it will be both more rare and more expensive (Deffeyes, 2001). As a result, less desirable crude oils containing heavy metals and contaminants (i.e., mercury and sulfur) will be processed. The resulting extensive pollution, along with concerns over climate change resulting from carbon dioxide emissions, make it highly desirable to find alternative sources for plastics. Many communities also are choking on solid wastes. Plastic water bottles in California are filling up available land fills and when released into the ocean cause a multitude of problems (Wilson, et al., 2003). Finally, during the production of plastics, and particularly of foamed plastic articles, significant quantities of volatile organic compounds (VOCs) are generated.
The purpose of this research project, conducted by PolyNEW, Inc., was to enhance bio-based green polymers using nanotechnology to address these many ecological concerns. The resulting ecobionanocomposites can compete on a price-performance basis with environmentally deleterious petroleum-based plastics.
Polylactide (PLA) is a bio-based material presently made from corn but available from any fermentable biomass resource, including plentiful cellulosics. Comprehensive life cycle inventory for PLA shows multiple environmental benefits over petroleum- based plastics (Vink, et al., 2003). The property window of PLA, however, is limited; the heat distortion temperature (HDT) is too low for some applications. In this project, nanocomposite technology was used to successfully overcome this limitation. A series of formulations containing cellulosic nanowhiskers (CNWs) was produced, their material properties evaluated, and the environmental characteristics of the best performing materials quantified.
In this study a small-scale twin-screw mixer was used to pilot the manufacturing process. Lactide was mixed with CNW and was polymerized to PLA/CNW nanocomposite in the twin-screw mixer. Process variables, including CNW loading levels, were varied to optimize nanocomposite formulations. The optimal process conditions were also determined to enable economic production.
Presently polystyrene is largely used for many applications and foamed with approximately 5 weight percent hydrocarbons. PLA can be foamed with carbon dioxide so the new technology has the ability to displace at least 1 million pounds per year of VOCs.
Technical goals for the project were met. The secondary technical target of a HDT of 80°C or above was met and exceeded. The primary technical target was an HDT of 100°C (to allow hot beverage applications) was also exceeded. By varying the loading of the cellulosic nanowhiskers (i.e. the weight fraction in the composite) and the processing conditions, it was possible to make sustainable nanocomposites having HDTs as high as 110°C. Additional property improvements were also realized including an increased modulus.
Figure 1. Improvement of HDT in the New Sustainable Nanocomposites Demonstrating the Attainment of Both Secondary and Primary Technical Targets
Life cycle assessment is a technique for assessing the environmental aspects and potential impacts associated with a product. A series of ISO standards, 14040 to 14043, provide detailed guidelines for conducting LCA (ISO 14040, 1997; ISO 14041, 1998; and ISO 14042, 2000). LCA studies the environmental aspects and potential impacts throughout a product’s life from raw material acquisition through production, use and end of life management options such as recycling, incineration and disposal. Clearly, such a full and detailed analysis was beyond the scope of this Phase I project, however, based on our bench and pilot scale data, we tracked 2 life-cycle impact categories, the water and fossil energy use required to create this novel nanocomposite material. We have tried to be consistent with the outline and general guidelines of the ISO standards for LCA when making our analysis. Based on a simplified system for producing CNW and the LCA performed by Vink et al for PLA, the estimated gross fossil energy requirement for the ecobionancomposite loaded with 25% CNW is 55.14 MJ/kg of nanocomposite pellets produced. The estimated water requirement for the ecobionancomposite is 43.22 kg water/kg of nanocomposite pellets produced. These values are very favorable compared to fossil fuel based polymers.
Based on the favorable attributes of the materials and technical success of the project, a Phase II commercialization partnership was formed with the Sealed Air Company. Sealed Air Corporation (SAC) is a Fortune 500 company and a leading global manufacturer of a wide range of food and protective packaging materials and systems, including such widely recognized brands as Bubble Wrap® cushioning, Jiffy® protective mailers and Cryovac® food packaging products. SAC is a global corporation with operations in 51 countries, including over 100 manufacturing facilities and 17,000 employees world-wide. In 2005 SAC revenue was $4.1 billion.
The Phase I project has been an enormous success – all technical tasks were completed and a multi-billion dollar commercialization partner, the Sealed Air Corporation (SAC), has been identified for partnering in Phase II. A letter of support for the research from SAC is included in the full version of the final report as testament to the technical and commercial relevance of the Phase I project.
Deffeyes KS, ed. Hubbert’s Peak: The Impending World Oil Shortage. Princeton University Press: Princeton, NJ, 2001.
Wilson E, Oldfield M, Drysdale D. Surge in bottle water popularity threatens environment. In: ENVIRONMENT, S.I.B.W.P.T., 2003 (available on the Internet at http://www.consrv.ca.gov/index/news/2003%20News%20Releases/NR2003-13_Water_Bottle_Crisis.htm Exit ).
Vink ETH, Ra’bago KR, Glassner DA, Gruber PR. Applications of life cycle assessment to NatureWorks™ polylactide (PLA) production. Polymer Degradation and Stability 2003;80(3):403-419.
International Standards Organization, ISO 14040, 1997.
International Standards Organization, ISO 14041, 1998.
International Standards Organization, ISO 14042, 2000.