Functionalised tannic acid + AldPi in PA66

Europium (Eu²⁺) – tannic acid (TA) complex with aluminium diethylphosphinate (AldPi) for PIN fire safety in polyamide, achieving UL 94 V-0 (2 mm) with lower total loading (8% AldPi + 2% eu-TA compared to 15% AldPi). The Eu-TA complex was produced by mixing aqueous solutions, centrifuge separation of the resulting dispersion, then drying, generating a complex with around 13% europium, 39% carbon, 47% oxygen+hydrogen. Peak heat release with 15% AldPI was over -40% lower than for neat PA66 and was over -40% lower with 8% AldPi + 2% eu-TA. This combination increases Limiting Oxygen Index from 26% for neat PA66 to 33%. This Eu-TA + AldPi combination also maintains PA66 mechanical properties significantly better than does 15% AldPi. Analysis showed that the Eu-TA resulted in a more compact and stable char layer than AldPi alone, and also reduced emission of combustible volatile gases.

“Bio-derived tannic acid-Eu(III) coordination synergizes with aluminum diethylphosphinate for low-loading and high-efficiency flame retardancy in PA66”, Z. Liu et al., RSC Adv., 2026, 16, 23399–23409, https://dx.doi.org/10.1039/d6ra02012g

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