DEPAL PIN FR in epoxy

DEPAL showed effective combination of fire performance and limited mechanical properties in amine-cured epoxy. Aluminium diethyl phosphinate (DEPAL) is a recognised, commercially available phosphorus-based PIN flame retardant. Because of possibilities offered by different curing agents and temperatures, epoxies are increasingly being adopted for large area additive manufacturing (3D-printing) enabling production of strong, lightweight components, e.g. for aerospace. But they are highly flammable. Particulate DEPAL from pinfa member Clariant was tested in Westlake Epoxy amine-cured resin at 0 – 20% w/w (0 – 4 % P), mixed into preheated resin (60°C) before curing. UL 94 V-0 was achieved with10% DEPAL for 3 mm thickness and 15% DEPAL for 2 mm thickness and peak heat release rate was reduced by around 50% for these loadings, but total smoke release was increased by less than +10%. DEPAL did not significantly modify the notched impact strength, toughness or brittleness of the cured epoxy, but does reduce the flexural strength (bending, elongation at break) by nearly 50%.

“Impact of Aluminum Diethyl Phosphinate (DEPAL) Flame Retardant on the Thermal, Mechanical, and Fire-Resistance Properties of an Amine-Cured Epoxy Resin”, M. Friedel et al., J. Applied Polymer Science, 2025; 0:e56923 https://doi.org/10.1002/app.56923

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