Manfred Döring, Fraunhofer LBF, presented development of PIN fire safety solutions for epoxy resins and epoxy resin / carbon fibre composites. Because the carbon in these composites can impact char formation, PIN FRs need to also act in the gas phase to be effective. DOPO-based phosphorus FRs do this by releasing PO. which acts as a radical scavenger in the flame. Fraunhofer, with industrial partners including Dow and DIC, has developed a number of specific DOPO, melamine, polyphosphate and polyphosphazene based solutions offering specific functionalities for expoxies.
N-reactive DOPO and bonded DOPO groups (bi-, tri- or polymeric DOPO) can react into the epoxy so avoiding migration and improving moulding homogeneity. Under heat, the bonds between DOPO groups will break preferentially to epoxy bonds, so improving processing temperature and use temperature characteristics.