Imagine preparing a shipment of your companys latest clinical trial. Its traveling from your headquarters in Boston to a research facility in Dubai in August and needs to be kept at 14Ëš C. Any deviation from this temperature means you risk losing thousands of dollars in product and R&D time. So, you tape up the box and cross your fingers.

This kind of shipment doesnt have to induce fear or stress. Its simply a matter of choosing the right packaging solution for your cold chain, with an emphasis on a cooling method, or phase change material (PCM). In addition to factors like price and payload protection, its becoming increasingly important to consider what kind of impact your packaging solution and PCM will have on the environment. Some PCMs leave a minimal carbon footprint, while others may be around for generations to come.

How It Works: Technically, every object on the earth is a phase change material. Add heat to a solid, it becomes a liquid. Add heat to a liquid, and it becomes a gas. Adding heat to a gas produces plasma (such as lightning). Even rocks, with enough applied heat, turn into liquid what we know as lava.

A phase change material in the packaging industry is defined as an organic or inorganic substance that acts as your payloads heating or cooling agent. As your payloads temperature increases or decreases (depending on several factors, from ambient external temperature to the type of insulation you use), your PCM works to maintain a stable, consistent temperature for the duration of its trip. 

Choosing The Right PCM: There are several commonly used phase change materials within the shipping industry, and each comes with its own benefits and drawbacks. It also should be noted that no PCM alone is effective in maintaining temperature, as they typically come as part of an entire packaging system. As the key temperature regulator for packaging systems, however, its important to choose your PCM carefully. Here are five simple categories to keep in mind when evaluating PCMs:

1) Payload protection temperature range. If your sensitive clinical trial needs to be kept at 14Ëš C, with acceptable excursions ranging from 11Ëš C to 17Ëš C, can you be sure your PCM will maintain that narrow temperature range?

2) Time durations. Will your packaging solution maintain a consistent temperature for 24-48 hours? Or with a package going to Dubai, are you safe up to 120 hours?

3) Ease of use. Does your packaging solution provide sufficient room for and protection of your payload for the duration of the trip? For instance, using dry ice as a PCM may be effective for materials that need to be kept frozen (below -18Ëš C). Once the ice sublimates, however, theres now room for the payload to move around and possibly become damaged.

4) Expense. Price alone shouldnt dictate your choice in packaging solution or PCM a more expensive option may be the best suited for your shipping needs. Reusable solutions also may appear 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, lets review some common packaging  PCMs: Water-based gel packs. While these solutions are among the most inexpensive PCMs available, theyre 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). Theyre biodegradable, non-toxic 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 (2Ëš-8ËšC) payloads because it freezes at 3.82Ëš C, heavy water is an effective PCM but must be used cautiously and could be difficult to obtain. Its 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 thats likely to change. With many of todays 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 nations landfills already full of EPS, its 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