ZnO/DOPO-Silane PIN Systems for FR PA6,6

Research shows that precision coating of PA6,6 fibres with ZnO and DOPO-silane exhibits catalytic flame-retardant effect. A commercial woven nylon textile (polyamide 6,6), 75 g/m2, was coated with atomic layer deposition (ALD) of zinc oxide (ZnO) at three different layer thicknesses (50, 84, or 199 nm), followed by a synergistic DOPO-silane phosphorus-silicon PIN flame retardant (DOPO-ETES from abcr GmbH) applied via sol-gel processing. Thermal analysis (TGA) and microscale combustion calorimetry (MCC) showed that the zinc oxide catalytically altered polyamide degradation and generated a physical fire-protective barrier, while the P-silane mainly promoted protective char formation. Together, the two coatings reduced the maximum TGA decomposition temperature by approximately 5%. Self-extinguishing was not achieved due to the melting behaviour of PA; however, a smoke-suppression effect was observed when ZnO was used. The authors note that the synergy between the two PIN compounds likely depends on the coating sequence.

“Thermal Behavior and Smoke Suppression of Polyamide 6,6 Fabric Treated with ALD-ZnO and DOPO-Based Silane”, W. Ali et al., DTNW, Materials 2025, 18, 3195. https://doi.org/10.3390/ma18133195