Monday, December 12th, 2011
Mills Industries Inc. (Laconia, NH) wanted to learn the full life-cycle environmental impact of its Endlock collapsible carton made of extruded polypropylene (PP), and how it compares to the impact of similar containers made of corrugated paper (CP) and a similar sized tote made of injection-molded high density polyethylene (HDPE). What they found is dramatic.
If you showed the three cartons to people on the street and asked which one had the least impact on the environment, it’s safe to say that most would point at the paper carton – but they would be wrong. The extruded corrugated polypropylene carton is by far the best friend of the environment. The global warming potential (GWP) impact of one of Mills’ PP cartons across its entire useful life is 84% lower than a similar corrugated paper carton and 83% lower than a similar HDPE tote.
The Life Cycle Analysis (LCA) was done for Mills Industries by SymbioSus Sustainability Consulting Inc. (Southborough, MA) using ISO 14040 and 14044 LCA methodology guidelines and specific LCA software (GaBi Professional 4.0). Each carton was assessed across each phase of its life, from resource extraction to end-of-life disposition, except for the use phase to keep the focus on materials and manufacturing.
The environmental impact categories measured in the study include the potential for water acidification, water over-nutrification, freshwater toxicity, soil toxicity, and smog formation, in addition to the global warming impact potential already noted. In all five study categories, the Mills PP carton had between 31% and 94% lower impact than the CP carton or HDPE tote.
According to SymbioSus, the key drivers of the PP carton’s lower impact are its greater durability, particularly compared to the CP carton, and its lighter weight to the molded HDPE tote, which requires more raw material. This comes as no surprise whatever to plastics industry professionals who have been promoting the outstanding strength-to-weight ratio of plastics materials for about a century.
Mills Industries had already lessened its environmental impact in several ways: its extrusion partner uses hydro-powered electricity; Mills buys green electricity for its plant; PP scrap is reground and recycled; and Mills encourages customers to recycle the cartons at the end of their useful lives. Also, the collapsible design of the Endlock corrugated PP carton means many more of them can be shipped in a truckload.
People on the street are can’t to be blamed for not knowing basic plastics characteristics such as high strength-to-weight ratio, even though that is a key reason why the new Boeing 787 Dreamliner’s fuselage is made of carbon-fiber-reinforced plastic, and BMW’s forthcoming electric and hybrid cars feature reinforced plastic composite body panels.
Mills Industries is currently educating its customers and others throughout industry about the environmental advantages of its extruded corrugated polypropylene carton. Tweeting this message or posting it to your LinkedIn and Facebook sites will help, too.