P hase change materials (PCMs) - materials that release, store or absorb heat to or from the surrounding environment as they change from a solid to a liquid state or vice versa - originally were developed for use in programs conducted by the National Aeronautics and Space Administration in the 1970s. Commercial applications, both textile and nontextile, date from the 1990s. PCMs - found increasingly in apparel, footwear and accessories; bedding; and other textile  applications to maintain a constant temperature and comfortable environment for the wearer or user of the article - typically comprise encapsulated paraffin materials tuned to change from solid to liquid and back within a set temperature range.

There now is a 100-percent bio-based PCM - PureTemp™, developed by Minneapolis-based Entropy Solutions Inc. - derived from waste by-products of vegetable oil production. Developed first to provide thermal management in packaging, shipping, electronics, healthcare, food storage, building materials and other such applications, the technology now is available also for textile applications. Some initial uses in cooling vests are based on the packaging system of liquid PCM-filled plastic packs. Other uses are in various stages of development using microencapsulated PCMs incorporated into a fabric or macroencapsulated materials that can be topically applied to a product. Applications in development include the commercial applications mentioned above in addition to carpet fibers and a baby car seat.

According to Entropy Solutions President Eric Lindquist, PureTemp PCMs offer higher levels of latent heat - stored heat that is released or absorbed when a substance changes from one state to another - than comparable paraffin-based PCMs, and those higher levels translate into improved thermal-regulating performance. "The ability to achieve higher latent heat is tied to purity levels," he said. "PureTemp is 98- to 99-percent pure. Paraffin comes from crude oil, and the more refined it is, the more expensive. In paraffin, that level of refinement would be extremely expensive - 12 to 15 times the cost of PureTemp."

Lindquist said PureTemp is offered in 210 different temperature ranges, as opposed to only about 20 for paraffin-based PCMs, which are limited by the paraffin's carbon chain makeup.

PCM product developer and marketer Outlast Technologies Inc., Boulder, Colo, uses PureTemp for some of its PCM temperature-regulation solutions. Melbourne, Fla.-based Glacier Tek Inc. is using the liquid-filled packs in its RPCM® Cool Vest products sold to military and police agencies, and its Chilly Dog® vests for working dogs.

May/June 2009

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For more information about PureTemp™ PCMs, contact Entropy Solutions +952-941-0306, www.entropysolutionsinc.com.