Intumescent Phosphorus and Triazole-Based Flame-RetardantPolyurethane Foams from Castor Oil

摘要

Synthesis of a novel phosphorus and triazole-functionalized flame-retardant (FR) monomer (PTFM) using azide–alkyne “click” reaction between triprop-2-ynyl phosphate and 2-azidoethanol that can impart intumescent FR property to polyurethane foams (PUFs) has been reported. Polyurethane triazole foams (PUTFs) were prepared using the as-synthesized PTFM and a hydroxylated castor polyol with a hydroxyl value of ∼310 mg KOH/g for application as reactive FR rigid foams. PTFM and the castor polyol were characterized for structural elucidation using Fourier transform infrared and ¹H, ¹³C, and ³¹P NMR. PUTFs with a varying loading content of PTFM were subjected to the lab-scale flame test, cone calorimetry test, Underwriters Laboratory 94 Vertical burning test (UL 94V), and limiting oxygen index (LOI) test. A significant increase in the char yields, reduction in heat release rates, V-1 rating, and 27% of LOI were observed for PUTFs compared to PUFs and proportional to the percentage loading of PTFM. The cumulative effect of nitrogen and phosphorus in PUTFs on their intumescent behavior was evident from the thermogravimetricanalysis and scanning electron microscopy micrographs, which werefurther supplemented by X-ray photoelectron spectroscopy studies,indicating expulsion of N2 and overall improvement in compressionstrength as well. Such environment-friendly reactive FRs can be goodreplacements to the halogenated ones.