World's lightest substance Mass High Tech June 23, 2003 Jay Rizoli As hot technologies go, aerogel is an innovation that's lacking in novelty. While it's the lightest and least dense solid substance in existence and has applications in buildings, automobiles, safety equipment, clothing and space exploration, it's actually more than 70 years old. "We laugh about it as being the oldest new product," said Jim Litrun, marketing and sales manager at Billerica-based Cabot Corp., a manufacturer of components for myriad consumer products. Aerogel is a highly porous solid formed from a gel, such as silica gel, in which the liquid is replaced with a gas - think of Jell-O without the water but maintaining its shape and internal structure. That remaining solid, descriptively called "frozen smoke" in some circles, is a transparent, nanoporous, hydrophobic, extremely low-density thermal insulator that is more than 95 percent air and can support more than 4,000 times its own weight. Those properties dictate aerogel's primary application as an insulator, both in building construction and in clothing. "The pore sizes in aerogel's delicate latticework are measured in nanometers, about 20 to 30 nanometers so that they actually separate molecules," Litrun said. "The Nanogel acts as a sponge so that molecules can't bump into each other, and it prevents heat transfer. It is so light that light goes through it but not heat. "The construction industry finds it absolutely captivating. You lose a tremendous amount of heat through windows and with this you get the light without the heat loss." Last year Cabot Corp. teamed with Manchester, N.H.-based Kalwall Corp. to produce what so far may be the crown jewel of aerogel application in a consumer setting: the pool-area ceiling at the Comfort Inn in Manchester, made of Nanogel Translucent Aerogel Insulation. Kalwall has developed a new super-insulated translucent panel that is infilled with Cabot's silica-based aerogel product, called Nanogel. The structural sandwich panel allows 20% light transmission while insulating at least five times better than regular glass and delivering insulation value of R-20. "There was ice formed on the outside of the panels while it was warm inside," Litrun said. Down the road in Marlborough, Aspen Aerogels is selling to the aerospace, apparel, cryogenics and insulation markets with aerogel products in the form of powder, beads and a flexible, fiber-reinforced aerogel composite blanket. The Cabot and Aspen products find their roots in the research of professor Steven S. Kistler, who developed aerogel in 1931 at the College (now University) of the Pacific in Stockton, Calif. Kistler, who was working with supercritical liquids - high-pressure liquids near the boiling point - discovered a way to extract liquid from wet silica gel to reveal a solid networked structure the same size and shape as the gel. Kistler's process required supercritical drying, but the high-temperature, high-pressure process was dangerous and allowed production of only small batches at a time. While Monsanto Corp. produced aerogel as an additive in paint and cosmetics in the 1930s and 1940s, the development of "fumed silica," which had similar properties, led the company to abandon it, and aerogel research halted for more than 40 years. In the more energy-conscious 1970s and environmentally conscious '80s and '90s, interest in energy efficient materials opened the door for companies such as Cabot and Aspen to pursue modern aerogel research. "People have been trying for years to find a way to mass produce it inexpensively, and we took the bait in the 1990s," Litrun said. "Cabot added a chemical step called silation, in which we graft water-repellent molecules to the surface of the silica," Litrun said. "That enables us to make it in a continuous process rather than in batches and dry it in atmospheric pressure, so we have reduced cost and increased volume." HOME | ABOUT KALWALL | RECENT PROJECTS | SPECIFICATION SUMMARY | CAD DRAWINGS | CONTACT KALWALL