The Rupp Report: Phase Change Materials (PCMs): A Modern Way Of Moisture Management
Jürg Rupp, Executive Editor
It started some 25 years ago with a company called Frisby Technologies. No, not Frisbee like the famous plastic disc — the chairman’s name was Greg Frisby. He had a funny idea to develop phase change materials (PCMs). The concept was to store body heat in the fabric of the garment. Store body heat? PCMs? This new idea made a lot of noise, particularly in the sports and leisurewear sector. Some years later, the Frisby name disappeared from the market. In 2004, Frisby was acquired by the current global PCM market leader, Golden, Colo.-based Outlast Technologies LCC.
Jump cut: But what are PCMs? The idea was originally developed for the aerospace industry. The astronauts in their protective suits were facing a lot of temperature differences while they were working in outer space.
It is commonly known that the human body can work as a power station: However, some 99 percent of body heat, produced by muscular work, is lost through the skin. This heat exchange or heat transfer is needed in order to guarantee a constant body temperature. The right — or wrong — garments have a significant influence in this temperature exchange. If more body heat is produced than can evaporate through the garment, the body overheats. On the other hand, if more heat flows from the body than desired, it results in hypothermia. This effect is very well-known in protective apparel. Many protective textiles provide a certain barrier against chemicals, heat and cold; but at the same time, they limit or even prevent the discharge of body heat, especially those made with functional membranes. How is one to carry on with this problem? That was the big challenge.
Phase Change Materials
So, the basic idea was to find a way on the one hand to better balance the body temperature, and on the other hand to store body heat. This was achieved using microcapsules of paraffin — also known as petroleum and petroleum jelly, and a byproduct of gasoline production. With PCMs, a certain material changes its physical state when temperature is applied. The oldest example of a PCM is water and ice.
There are many explanations and descriptions about the function of PCMs. According to Outlast: “PCMs are products that store and release thermal energy during the processes of melting and freezing. PCMs release large amounts of energy upon freezing in the form of latent heat but absorb equal amounts of energy from the immediate environment upon melting. This enables thermal energy storage; heat or coolness being stored from one process or period of time and used at a later point in time or transferred to a different location.”
And how does it work? When the temperature of the fabric containing the encapsulated PCMs exceeds a certain temperature, the PCMs turn into a liquid form. During this process, large amounts of heat from the environment are stored in the PCMs, and consequently, the skin gets cooler. If the environmental temperature — the body temperature — cools down, the PCMs crystallize and release the incorporated energy as heat to the body. In order to prevent leakage while the material turns to liquid, the material is enclosed in very tiny plastic beads from a few micrometers in diameter.
One may say this is not possible. When the author heard for the first time about PCMs, the reaction was the same: it can’t work, impossible. This assumption was totally wrong. For quite a long time, the author had a jacket with incorporated PCMs, which worked very well, even in very cold temperatures. In the 1990s, EMPA, the Swiss Federal Laboratories for Materials Science and Technology, made big lab checks with test jackets that incorporated PCMs. The results were astonishing. The process worked very well, and with some pictures, taken by an infrared camera, one could see the different areas of incorporated heat in the jacket. Since then, PCMs have made a very big step forward to become an important part of all kinds of applications such as sportswear, cold and heat protective textiles, and even home textiles.
Two recent studies conducted in the United States state that the use of PCMs will further increase by 20 percent annually. A study from Markets & Markets, Dallas, says that from a current global turnover of some US$460 million, consumption will increase up to US$1.18 billion in the year 2018. Another survey from Transparency Market Research, Albany, N.Y. reports similar figures and forecasts: from US$350 million in 2011 up to US$1.18 billion in the year 2018. The most important markets by now are Europe and North America, with a market share of 30 percent each. However, other markets are becoming more important and interesting for the producers.
At the recent Heimtextil, the Rupp Report spoke to Barbara Fendt, Outlast’s marketing manager for Europe. She said that the Outlast® technology does not work with the wicking technology, which pulls body moisture away from the skin to the outer layer of the garment. “Outlast technology proactively manages heat while controlling the production of moisture before it starts. That’s the Outlast difference,” she said. Here are some stated benefits of the technology in a nutshell:
- absorbs excess body heat;
- manages moisture;
- reduces overheating;
- reduces chilling;
- reduces perspiration; and
- continuously adapts to thermal changes
Outlast products are already applied in various end-uses. Of course, at Heimtextil, all exhibitors are focused on the home textiles sector. According to Fendt, the company has released a new product for the home textiles business: PCM fiber balls applied in bedding. As the company reports: “The PCM fiber balls based on polyester offer besides PCM waddings a new possibility to balance temperature in duvets or pillows and to reduce humidity significantly while sleeping. The new PCM fiberfill manages the climate inside the bed proactively and reduces sweat production right from the beginning, so less humidity is created inside the bed which leads to more comfort and a better night’s rest.” Fendt said that the new balls are suitable for bedding products that have synthetic fillings. This could be an interesting and promising application for hospital bedding. The feel of the fiber balls is indeed very soft, and they are said to be handled very easily in production.
Many skeptical readers may say that this time, the Rupp Report is writing nonsense. It is the other way round: One has to test the material, and this trial usually convinces one to do further product development. The difference between some existing membranes that claim to be functional and PCMs is simple: PCMs work. And that is probably the reason why the two surveys mentioned above predict such a growing market opportunity for this fascinating material.
February 4, 2014