Synthsis Of The Derivatives Of Cyclotriphosphazene And Study On Their Flame-restardant Properties

According to the rapid development of the technology and science, the application of polymer materials becomes more and more widely in our daily life. In recent years, several novel flame-retardants have been developed. Phosphorus flame retardants get much attention because of their good flame resistance, catalyzing carbonization, low smoke evolution and low heat release rate. Cyclotriphosphazene with reactive chorine atom show unusual thermal properties such as flame resistance and thermal stability. Derivatives of cyclotirphosphazene, which are regarded as one kind of the most suitable replacement of halogen flame-retardants, can be obtained from the reaction of hexachlorocyclotriphosphazene with alcohol or amine. In this paper, three different phosphazene derivatives were synthesized and characterized. The derivatives were coated on polyester fabrics; the flame retardant properties and flame retardant mechanism were studied in detail. The derivative with best flame retardant property was also used to modify PU, the flame retardant properties and flame retardant mechanisms were studied.1. Synthesis and characterization of cyclotriphosphazene derivatives.The cyclotriphosphazene derivatives hexakis(4-hydroxymethylphenoxy) cyclotriphosphazene(HHMCP), hexakis[4-(diphenylphosphoroxymethyl)pheoxy]- cyclotriphosphazene(HDPCP) and hexakis[4-(diethylphosphoroxymethyl) pheoxy]-cyclotriphosphazene(HDECP) were synthesized and characterized by Fourier transform infrared spectroscopy(FTIR), Nuclear magnetic resonance(NMR). By thermogravimetric analysis(TGA),we found that HMMCP, HDECP and HDPCP had good thermal stability; the char residues are 51.38%, 43.14% and 57.56% in the air at 600 o C, respectively.2. Study on the flame retardant properties of cyclotriphosphazene derivatives applied on coated polyester fabrics.The composite materials HDECP / polyester, HDPCP / polyester and HHMCP / polyester were prepared by coating flame retardants with the contents 0%, 1%, 2.5% and 5% on the surface of the polyester fabrics. The thermal stabilities and char residues of coated polyester were investigated by TGA. The results showed that HDECP, HDPCP lowered the initial decomposition temperature of polyester fabrics; but HHMCP slightly increased the initial decomposition temperature. The addition of the flame retardants could reduce the maximum rate of thermal degradation and increase char residues of polyester fabrics in air and nitrogen atmosphere. The char residue of HHMCP / polyester was slightly higher than HDECP / polyester and HDPCP / polyester. The LOI values of HDPCP/polyester, HDECP/ polyester and HHMCP/ polyester were 28.2%, 28.0% and 24.1%, respectively. HDECP / Polyester and HDPCP / polyester could pass UL-94 B1, having good anti-dropping properties. Py-GC/MS tests indicated that three flame retardants restrained the in-depth pyrolysis of coated polyester. It was found that HDECP has the best flame retardant effect.3. Study on the flame retardant properties of HDECP applied on polyurethane.The composite materials HDECP/PU were prepared by melt blending with HDECP contents 3%, 5%, and 8%.Thermal gravimetric analysis(TGA) study showed that the addition of HDECP could improve the initial decomposition temperature of modified PU, and the maximum rate of thermal degradation was significantly reduced. The composite material with 8% HDECP / PU char residues raised 2400% and 682% in nitrogen and in air atmosphere at 800 ?than pure PU. The LOI values of 3%, 5%, 8%HDECP / PU composites reached 28.3%, 35%, 30.8%, respectively, which could pass UL-94 V-0. It revealed that flame retardant HDECP inhibited the in-depth pyrolysis of PU.