Race cars, mattresses and sound pads may hardly sound like materials that aid a space mission. Yet, the flame-retardant capability in these earthly products, thanks to an additive for polyurethane foam developed by Clariant, may just be the thing needed to make man’s first flight to Mars safer.
Clariant’s non-halogenated Exolit® OP products already help repel automobile fires. When burned, vehicle plastics that contain them rapidly form a protective foam layer of char that is no longer combustible. The protective layer also cuts out the oxygen that feeds the fire. Engine plastic parts containing flame retardants also help prevent sparks from electronic components from turning into fires.
With NASA preparing to send the first humans to Mars by the 2030s, Clariant’s innovative flame-retardant additives were explored to make the expedition safer.
Through a NASA-funded research project between Clariant and the Florida Institute of Technology, researchers worked together to develop a more environmentally friendly flexible foam from the Exolit OP 560 series to replace rigid spray-on foam insulation.
While oxygen is substantially lacking in space, there’s still risk of fire from other atmospheric conditions, the International Association for Advancement of Space Safety and the International Space Safety Foundation said in an article on NASA’s planned Mars mission. Overheating of the spacecraft’s propellants was another factor, they noted.
“What NASA was interested in was a flexible foam that would have properties at least as good as their rigid spray on foam insulation,” said Gordon L. Nelson, professor of chemistry at Florida Institute of Technology. “We have identified Exolit OP 560 as a key ingredient in the flame-retardant flexible foams we were making.”
Prior space programs highlight the importance of flame retardant foam materials in building rockets. The fuel tank, for example, the single largest part of a space shuttle, mostly made of .32 cm thick aluminum, is the only part of the shuttle that cannot be refurbished and reused on multiple missions, meaning it is “disposable.” Polyurethane foam has been used in past missions to insulate the outer layer of the tank and protect it from the external heat of the burning rocket fuel, keeping the contents of the tank super cooled at -253 °C.
Since the disaster of space shuttle Columbia in 2003, the loss of foam on the external fuel tank has been a significant area of interest for NASA. The Columbia Accident Investigation Board did not evaluate alternative materials but highlighted the need for change.
As NASA develops new rocket technology for its Mars mission, flame retardants can play a critical role. Clariant’s Exolit OP 560 has not been used in space previously. But it has passed rigorous fire tests for multiple commercial applications that include furniture and mattresses, as well as aviation and race car seating and acoustic sound padding. The eco-friendly foam is also energy absorbing, enabling users to sit and even leap on it.
Exolit OP 560 is a reactive flame retardant that eliminates unwanted emissions since it becomes chemically bonded within the polymeric polyurethane foam structure. As a result, the flame retardant cannot leave the foam during use. The additive is also halogen-free, and has a more favorable toxicological and environmental profile. In particular, it cannot bioaccumulate in humans and other organisms since it is "locked" into the foam.