Pour in Place Polyurethane Foam Performance as an Impact Mitigation and Flame Retardant Material Used in Nuclear Material Transportation Containers – The Mechanism of Intumescence

The purpose of this study is to explore the key mechanisms responsible for the effectiveness of General Plastic’s radioactive material packaging systems, and to apply the most current findings towards their improvement. Predictable failure mechanisms have been shown to be important for optimal effectiveness as an impact mitigation material. A characteristic crush response serving to dampen energy transfer across interfaces is well established in our systems. However, previous findings have shown that the most significant distinguishing characteristic, when comparing General Plastics’ systems to alternatives, is the unique intumescent properties. In simulated accident testing, where a sample container is damaged, then burned, the material exhibits the ability to self-heal as a result of the expansion associated with intumescence. This provides gas-phase flame inhibition, condensed-phase flame/heat blockage, and oxygen starvation through the closing off of fractures resulting from the simulated damage. In this study we have explored the mechanism of intumescence in greater depth, and utilized these principles in the development of new systems. Herein, two novel systems targeted at improving flame retardancy through optimized intumescence are described.