Parcel - August 2008 - (Page 19) pear more expensive, but based on cost per use will most likely end up being more affordable. 5) Environmental impact. What is the PCM composed of, and is it renewable? Is it toxic or non-toxic? Can you reuse it? With this in mind, let’s review some common packaging PCMs: Water-based gel packs. While these solutions are among the most inexpensive PCMs available, they’re not always the most effective. Ice melts quickly (resulting in a drippy package), and gel packs can sometimes provide inconsistent temperature control. Gel packs may also need to be conditioned hours before use to avoid thermally shocking the payload. They are both, however, non-toxic, and intact gel packs may be used several times. Dry ice (frozen CO2). Inexpensive and readily available (but not reusable), dry ice works well with deep frozen payloads traveling short distances. Also, be aware of any possible shipping restrictions that you may encounter with dry ice. Vegetable oil-based PCMs. Derived from an organic, renewable derivative of vegetable oil, these relatively new-to-market PCMs can achieve virtually any temperature range and maintain it for extended durations of time (currently available vegetable oil-based PCMs exceed 120 hours). They’re biodegradable, nontoxic and experience no thermal degradation after 20,000 uses. Petroleum-based PCMs. Directly derived from crude oil, the price of petroleum-based PCMs fluctuates as often as the price of gasoline. Depending on the petroleum derivative used to create the PCM, most are toxic and unsafe for the environment. Because they are typically volatile (like oil-based paint), disposing of petroleum-based PCMs may be difficult. Heavy water (deuterium oxide). Ideal for refrigerated (2˚-8˚C) payloads because it freezes at 3.82˚ C, heavy water is an effective PCM but must be used cautiously and could be difficult to obtain. It’s also the most costly at hundreds of dollars per kilogram. Eutectic salts. A generic term for many materials that contain a salt in solution at a concentration that yields the lowest freezing point, eutectic salts can vary immensely in safety, price and effectiveness based on their composition. There may also be disposal or customs issues, again, based on the material used. It may not be commonplace yet in your company to consider environmental impact when evaluating products or services, but that’s likely to change. With many of today’s top brands implementing corporate social responsibility initiatives, and Europe, China and Japan all implementing packaging waste laws around the use of reusable or recyclable packaging, the US may not be far behind. With more than one-third of the nation’s landfills already full of EPS, it’s time we all consider sustainability when thinking about temperature-controlled packaging solutions. Eric Lindquist is the President of Entropy Solutions, Inc., a thermal technology development company. He can be reached via email at eric@entropysolutionsinc.com. ■ www.PARCELindustry.com August 2008 19 http://www.PARCELindustry.com
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