Posted on 04/04/2023 in Fire Safety 2023
Phosphorus silica PIN FRs synergy

Phosphorus and nitrogen functionalised silica showed to be an effective flame retardant in thermoplastic polyurethane. Silica was amine then propargyl functionalised, then reacted with a phosphorus and nitrogen containing derivate of pentaerythritol using alkine-azyde “click” chemistry. This produced a phosphorus functionalised silica (PhosFS = 2,6,7-Trioxa-1-phosphabicyclo [2.2.2]octane, 4-(Azidomethyl)- 1-oxide, a phosphorus molecule similar to PEPA). With 10% loading of PhosFS in thermoplastics polyurethane (TPU), UL 94 V-0 (3 mm) was achieved with no flaming dripping (NR for neat TPU, V2 for the same loading of non-functionalised silica). LOI was increased from 19% (neat TPU) to 28.5%, char residue at 700°C increased from 4% to 20% and thermal stability was increased from 291°C to 308°C. These effects are considered to be due to generation of a uniform and dense char and linking between the PhsFS and the TPU.

“Phosphate functionalized silica for improved flame retardancy and thermal stability of thermoplastic polyurethane”, Shhikha, L. Nebhani et al., ACS Appl. Polym. Mater. ACS Appl. Polym. Mater. 2022, 4, 9, 6332–6341,

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