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

At present,polymeric materials has been widely used in the automobile,construction,electronic and aerospace industries.However,the inherent flammability of polymeric materials limits their applications,especially those requiring good flame retardant behavior and high heat resistance.It has been widely recognized that adding flame retardant into the polymer materials can effectively reduce their flammability.However,the application of halogen–containing materials in the polymers leads to environmental problems.Thus,organic phosphorus compounds are regarded as the most promising halogen-free flame retardants owing to its low flue gas release,high flame retardant efficiency,and small hazard to ecological environment during combustion.The purity of the flame retardant has greatly affected its thermal stability.In industry,solution crystallization is an important separation and purification process for flame retardant,and the solvent is very cruscial for the process of crystallization.Furthermore,homogeneous mixing between polymer and flame retardant via solution casting method can avoid mechanical strength and ductility reduction of polymer materials.Therefore,seeking a proper solvent via analyzing solubility data of flame retardant is required for not only the purification of flame retardant but also the application of solution casting method in industrial production.The solid-liquid phase equilibrium measurements of organic phosphorus compounds not only are useful for the fundamental data for the characteristics of products but also supply the database for assessing the applications and limitations of the continued development of solution models established for describing the thermodynamic properties.For these reasons,the main contents of this dissertation are summarized as follows:Resorcinol bis(cyclic 2,2-dimethyl-1,3-propanediol phosphate)(RCDMPP)was synthesized from neopentyl glycol,phosphorus oxychloride,and resorcinol.N,N'-piperazinebis(neopentylglycol)phosphoramidate(PBNGP,)was synthesized from neopentyl glycol,phosphorus oxychloride,and piperazine.They were characterized by elemental analysis(EA),fourier transform infrared spectroscopy(FTIR),mass spectra(MS)and nuclear magnetic resonance(NMR).The purity of RCDMPP and PBNGP were measurement by high-performance liquid chromatography(HPLC).The thermal stability of RCDMPP and PBNGP were evaluated via thermogravimetric analysis(TGA).The fusion enthalpy and melting point of RCDMPP were detected by differential scanning calorimetry(DSC).The solubilities of RCDMPP and PBNGP in selected solvents at T =(293.15 to 333.15)K and atmospheric pressure were measured via a static-analytic method for the first time.The results were as following:The solubility of RCDMPP in all the selected solvents increases with rising temperature.At room temperature,the order of solubility of RCDMPP is chloroform >1,2-dichloroethane > acetonitrile > acetone > ethyl formate > methyl acetate > methanol >ethanol > n-propanol > ethyl acetate > toluene > hexane.At a high temperature,the order of solubility of RCDMPP changes to be chloroform > 1,2-dichloroethane > acetonitrile >methanol > acetone > ethyl formate > ethanol > methyl acetate > n-propanol> ethyl acetate >toluene > hexane.The solubility of PBNGP in all the selected solvents increases with increasing temperature.At room temperature,the order of solubility of PBNGP is as follows:chloroform > acetone > tetrahydrofuran > toluene > 1,2-dichloroethane > ethyl formate >n-propanol > acetonitrile > i-propanol > methanol > benzene > methyl acetate.At a high temperature,the order of solubility of PBNGP changes to be as follows: chloroform >acetone > tetrahydrofuran > ethyl formate > toluene > 1,2-dichloroethane > n-propanol >methanol > acetonitrile > i-propanol > benzene > methyl acetate.The solubility data of RCDMPP and PBNGP were correlated with Apelblat,?h,NRTL,Wilson,and UNIQUAC models.The results show that all the models are able to repeat the solubility data well with optimized parameters.The solubility parameter of RCDMPP and PBNGP were estimated by the Scatchard–Hildebrand model,meanwhile the dissolution enthalpy,and entropy in the selected solvents were also calculated by the Van't Hoff equation and Gibbs–helmoholtz equation.The solubility parameter(?),UNIQUAC volume parameter(r)and UNIQUAC surface parameter(q)of RCDMPP,PBNGP and other over thirty phosphorus–containing flame retardants were estimated by group contribution method,and the solubility parameter of these phosphorus–containing flame retardants are agreement with the values obtained by Scatchard-Hildebrand model.The fusion enthalpy and melting point of PBNGP were estimated by group contribution method.The fusion enthalpy of isonicotinic acid was estimated by group contribution method,and the result showed a large difference with the value as reported from literatures and as determined by DSC.The results of DSC/TG measurement showed that the phase transition of isonicotinic acid underwent a sublimation process,and the value for the fusion enthalpy of isonicotinic acid determined by using DTA or DSC was proved incorrect.The DSC/TG measurement and pyrolysis-gaschromatography/mass Spectrometer(Py-GC/MS)measurement were done to show this conclusion.