Researchers found that the newly developed phosphorus-based poly(urethane-triazole)s (P-PUTs) exhibit excellent flame-retardant properties by self-extinguishing after the removal of the flame.

Thermal behaviour, elemental and morphological properties of the synthesized P-PUTs were comprehensively investigated employing thermogravimetric analysis (TGA), field emission scanning electron microscopy (FE-SEM), and energy-dispersive X-ray spectroscopy (EDX), respectively. The flame retardant properties of P-PUTs were assessed by UL–94 vertical burning test, limiting oxygen index (LOI) and lab-scale flammability test. All the P-PUT compositions were found to self-extinguish immediately after the removal of flame with a V-0 rating of UL-94 V, the LOI value (vol%) are 26.3 %, 28.2 % and 29.0 % for H2P-PUT, I2P-PUT and T2P-PUT, respectively and the corresponding char yields were 26.03 wt%, 25.76 wt% and 39.58 wt% along with significant intumescence. This apart, the films with a transparency of 96.5 %, 96.7 % and 94.3 % in the visible wavelength for H2P-PUT, I2P-PUT and T2P-PUT, respectively, can possibly make these P-PUTs materials attractive as fire retardant top coats on wood substrates.

Source: Progress in Organic Coatings Volume 188, March 2024, 108228