Synthesis And Study On The Themophysical Properties Of The Phosphorus-containing Flame Retardants

Flame retardants are one of the most important auxiliary for polymer materials, and they can effectively prevent or delay the polymer materials burning. With the enhancement of human health and environmental awareness, the development of flame retardant with environment protection, low toxicity, high efficiency and multi-function has become the trend of the future. Organic phosphorus flame retardant, as a halogen-free system, has wide development potential owning to high flame retardant efficiency, low toxicity, low corrosion and good compatibility with polymer material. Data of solubility plays a very important role for selecting the solvent during the synthesis process for flame retardant, and a suitable solvent should not only restrain the generation of by-products, but also be benefit for the target products and make the product easy separation. Therefore, the systematic and complete data of solubility could be provided the important basis for selecting the solvent in the process of flame retardant and its purification, and the foundation for the solid-liquid equilibrium. Among the practical application, people are more concerned about the the flame retardants thermal decomposition and thermal stability of the quantitative data. Thermogravimetric analysis(TGA) can precise determination of the change in mass of flame retardants, and to study the whole process of change in the substance heated in the observed temperature range. Therefore, the quantitative research of flame retardant thermal decomposition properties is both important theoretical and certain practical significance. For these reasons, the main contents of this dissertation are summarized as follows:The phosphorous flame retardants of phosphoric acid, P,P’-1,4-phenylene P,P,P’,P’-tetraphenyl ester(PAPTE) and diphenyl anilinophosphonate(DPAP) were prepared by diphenyl chlorophosphate, hydroquinone and aniline respectively. A caged bicyclic phoaphate flame retardant of 4-(Hydroxymethyl)-1-oxido-2, 6, 7-trioxa-1-phosphabicyclo[2.2.2] octane(PEPA) was prepared by pentaerythritol and phosphorus oxychloride. A phosphate salt flame retardant of phenyl phosphate disodium salt(PPDS) was prepared by phenylphosphonic acid(PPOA) and sodium hydroxide. The structures of all compounds were characterized by elemental analysis(EA), massspectrometer(MS), infrared spectroscopy(IR), nuclear magnetic resonance(1H NMR) as well as high-performance liquid chromatography(HPLC) and their spectral properties were discussed. Their melting point, melting enthalpy and thermal stability were studied by differential scanning calorimeter(DSC) and thermogravimetric analysis(TGA).Thermal degradation behaviors of phosphoric acid, P,P’-1,4-phenylene P,P,P’,P’-tetraphenyl ester(PAPTE) and diphenyl anilinophosphonate(DPAP) in a nitrogen atmosphere were studied using thermogravimetric analysis(TGA) techniques.The activation energy of the decomposition process for the PAPTE and DPAP were calculated through the Friedman’s isoconversional, Kissinger-Akahira-Sunose(KAS) and Flynn-Wall-Ozawa(FWO)methods by the extent of conversion. 19 degradation functions’ apparent activation energies and pre-exponential factors were calculated using the Tang method. The values of compensation parameters(Bv and Iv) were then calculated from the slopes and intercepts of the straight lines observed. Thus, the values of the invariant activation energy(Einv) and pre-exponential factor(Ainv) were calculated. Using kinetic parameters Einv and lnAinv, a kinetic equation appropriate to the most probable mechanism of a process can be found. The thermal decomposition behavior provides a theoretical basis for its application in polymer materials.The solubilities of PAPTE, DPAP, PEPA, PPOA and PPDS in the selectcommon pure solvents and mixed solvents were measured by static analytical methodfor the first time and included: the solubility data of PAPTE in methanol, ethanol, acetone, ethyl acetate, acetonitrile, methyl acetate, toluene, ether, n-propanol and i-propanol; the solubilities of PAPTE in the binary acetone + methanol mixed solvent; the solubilities of DPAP in acetonitrile, methanol, chloroform, ethanol, acetone, toluene, i-propanol, n-propanol, methyl acetate, ethyl acetate, 1,2-dichloroethane, and tetrahydrofuran; the solubilities of PEPA in methanol, acetonitrile, acetone, ethanol, i-propanol, n-propanol, ethyl acetate and chloroform; the solubilities of PPOA in chloroform, n-propanol,ethyl acetate,i-propanol,acetone,acetic acid and methyl acetate; the solubilities of PPOA in the binary acetic acid+ n-propanol and acetic acid+ acetone mixed solvent respectively; the solubilities of PPDS in acetone, methanol,ethanol and water; the solubilities of PPDS in the binary methonal+ water mixed solvent. The solubility ofphosphonic acid, P, P’-(1, 4-piperazinediyl)bis- P, P, P’, P’-tetraphenyl ester(PAPBE), N, N’-[1,3-Phenylenebis(methylene)]bis(phosphoramidic acid) P, P, P’, P’-tetraphenyl ester(PNBE) and PEPA in the four selected alcohol ether solvents, such as 1-methoxy-2-propanol, 1-propoxy-2-propanol, 1-methoxy-2-propyl acetate and 2-(2-methoxypropoxy) propanolwere measured by static analytical method.The solubility against the temperature was investigated and the influence of it was summarized with the molecular structure. Using the binary interaction parameter equations, the activity coefficients of the solutes were calculated. It provides theory basis for the compounds synthesis and solvents selection in purification processes and also provides the basic thermodynamic properties data for the further industrial application.The solubility data of PAPTE, DPAP, PEPA, PABTE and PNBE at different temperatures in selected solvents were correlated with λh equation, Wilson, UNIQUAC and NRTL thermodynamic model.The results showed that the calculated values were in good agreement with the experimental data and the relative standard deviations of most binary systems were less than 2%. According to the Scatchard-Hildebrand activity coefficient model, solubility parametersof PAPTE, PEPA and DPAP were calculated. Using the Fedors group contribution method, the solubility parameters for the phosphorus flame retardants composed by our researched group were calculated. The values of the solubility parameters come from the Fedors group contribution method and Scatchard-Hildebrand activity coefficient model were compared. The relation between binary interaction parameter l12 with temperature was investigated. The activity coefficient and the partial molar excess enthalpy at infinite dilution were predicted by Gibbs-Helmholtz equation. The dissolution enthalpy, and entropy in the selected solvents were also calculated by the Van’t Hoff equation and Gibbs-helmoholtz equation, meanwhile comparing the enthalpy and entropy value on the influence of Gibbs free energy.PAPTE and DPAP-MCA were used in polyurethane(TPU) as flame retardants. The retardant properties and mechnical properties were studied. The results show that PAPTE and DPAP-MCA are the good flame retardants for TPU. The tensile strength, elongation at break and tear strength of TPU matreials were reduced in different degrees when flame retardants were added into TPU.