Polymer Sustainability Metrics Compared

The first study of petroleum-based versus biomass-derived polymers evaluated by comparing green chemistry and engineering design principles against life-cycle analysis (LCA) environmental impacts has found mixed results: Although biopolymers rank high in terms of green design, they exhibit relatively large environmental impacts from their production and are beaten by polyolefins in LCA rankings (Environ. Sci. Technol., DOI: 10.1021/es101640n). A team led by Amy E. Landis of the University of Pittsburgh evaluated a dozen polymers: seven derived from petroleum, four from biomass feedstocks, and one in part from both sources. The scientists analyzed parameters such as use of renewable resources, waste prevention, biodegradability, percent recycled, transportation, price, health hazards, and energy use. Ranked by green design, the biobased polymers polylactic acid and polyhydroxyalkanoate came out on top. But ranked by LCA, polypropylene and high-density polyethylene were at the top of the list. Complex polymers such as polycarbonate and polyvinyl chloride came out at or near the bottom in both rankings. The study’s authors conclude that adhering to green design principles reduces overall environmental impact for all types of polymers, but switching from petroleum feedstocks to biofeedstocks does not necessarily provide benefits.