Synthesis Of Phosphoramidates And Study Of Their Flame Retardant Properties

In this article, starting from phosphorus oxychloride,1,3-propa-nediol, N-(2-hydroxyethyl)piperazine,2-[4-(2-hydroxyethyl)]piperpazinyl-2-oxido-1,3,2-dioxaphosphori-nane (PN1) was synthesized in70%yield, and also, diethy1{2-[4-(2-oxido-1,3,2-dioxaphosphori-nan-2-yl)-piperpazinyl]} ethyl phosphate (PN2) was obtained from the reaction of PN1with diethyl chlorophosphate in70%yield. The structures of PN1and PN2were characterized by1HNMR,13CNMR, FT-IR spectra and HRMS respectively.Phosphoramidates PN1and PN2were applied on cotton fabrics by the dip-pad-cure process respectively. The thermostabilities, changes of surface morphology and flame retardant properties of the cotton fabric samples were then studied.The thermal gravimeric analysis (TGA) showed that the initial decomposition temperatures of cotton fabrics treated with PN1and PN2were lower than the untreated one. Furthermore, the amounts of char residue for the treated samples were much higher than the untreated one at600℃respectively.The surface morphological changes of the treated cotton samples were observed through SEM micrographs before and after burning. It is showed that both PN1and PN2can form a protective char layer on the top of treated cotton samples. This kind of char layer could be useful to stop the burning process.The flame retardant properties of cotton fabrics treated with PN1and PN2were studied by limited oxygen index (LOI) measurement. The LOI reached29.1%and30.1%from initial18%when PN1was applied at the level of22%and27%respectively. The LOI reached28.4%,29.8%and33.1%from initial18%when PN2was applied at the level of17%,22%and27%respectively.It was concluded that phosphoramidates PN1and PN2both showed good flame retardant properties on cotton fabrics, and PN2had higher LOI values as it has higher phosphine content within its molecule.