Tuesday, July 7, 2009

Composites Emissions... EPA Fines Composite Pultruder $151k

Not all composite materials are equal when it comes to emissions; different resins have different properties when it comes to VOCs. Additionally, the intensity of emissions varies from process to process, such that wet lay-up, pultrusion, compression molding, autoclave, etc, all have different environmental impacts.

One of the most common resins used in thermoset composites today, is vinyl ester resin. This resin has been long proven, is inexpensive, has excellent corrosion and chemical resistance, and is easy to work with. (long pot life, good vescosity, good shelf life). Unfortunatly, this resin has a moderate Volitile Organic Compound (VOC) content, as the resin is dispersed with a monomer, (most often styerne.) Styrene is known to have health effects, and in large quantities can harm air quality. In fact, the US EPA has described styrene as "a suspected carcinogen" and "a suspected toxin to the gastrointestinal, kidney, and respiratory systems, among others."

By switching to low or no VOC resins such as certain epoxies and polyurethanes, the health risks can be avoided. Although costs are often higher, and often the resins are not yet adapted to the manufacturing process. Additionally, the increased use of thermoplastic resins are also helping reduce volitile emmisions.

As well, the various manufacturing processes of composites variy the intensity of emissions. Wet or hand lay-up, where a laminate is cured open to the air, is far worse then a closed mold oporation. I am curious how the EPA takes this into consideration?

Recently, the EPA fined a Minnosta
composites company, Conett Inc. (formally Geotek Inc.) $151,000 for violating "national emission standards for hazardous air pollutants by failing to reduce organic hazardous air pollutants from its pultrusion operations." The compliant can be read here.

As a compairson, here are two other EPA fines from 2003 and 2004, for the use of Styrene in hot tub manufacturing.

If you have any comments or insights, please share...

Photo credit: pfala vis flicker

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