The industry widely uses flexible elastomeric foams (FEFs) for thermal and acoustic insulation in air-conditioning and heating installations. Flame retardant foams are more or less solely based on two different rubbers:
NBR and NBR/PVC-based FEFs are the most widespread polymers for standard FEF’s while companies use EPDM mainly for applications requiring higher temperature resistance, e.g., solar applications.
PVC resins are blended with NBR to increase ozone and abrasion resistance. Also, PVC has the effect of increasing the level of fire retardancy, and you can further improve this by the addition of flame retardant fillers.
Applications such as automotive and furniture use polyurethane (PU) foams. When PU foams need to have fire resistance properties, you can add expandable graphite into the isocyanates + polyol mix. As a result, this will give intumescent properties to the foam.
In case of a fire or when heated above a certain temperature, expandable graphite will expand and create a protective carbonaceous char that effectively insulates the rest of the foam from the heat source.
LKAB Minerals can supply various grades of FireCarb (expandable graphite) with different expansion rates, particle sizes, and onset T of expansion.