Preparation And Properties Of Magnesium-based Functionalized Flame Retardant And Intrinsic Flame Retardant Polyesters

Polyethylene terephthalate（PET）is widely used in product packaging,fabric and electronic components because of its good mechanical properties and thermal stability.However,PET has flammable characteristics,in order to improve the flame retardant performance of PET,physical addition is usually used to achieve the purpose of flame retardant,but added flame retardant will have a bad impact on the mechanical properties of PET.In this paper,the functional monomer was designed from the aspects of monomer structure,elements contained in monomer and the influence of different monomer complexes on the flame retardant and mechanical properties of PET,and the intrinsic flame retardant PET was prepared by polycondensation.The specific research contents are as follows:1.A kind of organic and inorganic hybrid functional flame retardant MH-PPOA with symmetrical structure was prepared by using phenyl phosphoric acid and magnesium hydroxide as raw materials.The morphology and structure of MH-PPOA were characterized by scanning electron microscopy（SEM）and Fourier transform infrared spectroscopy（FTIR）.A high performance polyester with both flame retardancy and mechanical properties was prepared by introducing functional flame retardants into molecular chains of PET by means of polycondensation.The structure of（MH-PPOA）₁₅-co-PET was characterized by ¹H-NMR spectra.The flame retardancy and mechanical properties of（MH-PPOA）_n-co-PET were investigated.The results show that（MH-PPOA）₉-co-PET has the best comprehensive performance under the comprehensive consideration of flame retardancy and mechanical properties.The limit oxygen index of（MH-PPOA）₉-co-PET increases by 6.3%,and UL-94 reaches V-0 grade.Compared with pure PET,peak heat release rate（PHRR）,peak smoke production rate（PSPR）,peak carbon monoxide production rate（PCOPR）and peak carbon dioxide release rate（PCO₂PR）were reduced by 55.9%,35.3%,58.8%and 57.2%,respectively.2.A monomer（PBDA）was synthesized by the reaction of phenyl dichlorophosphoric acid and p-aminobenzoic acid,and then the PBDA was reacted with magnesium hydroxide to obtain the functional flame retardant MH-PBDA.（MH-PBDA）_n-co-PET was prepared by introducing MH-PBDA into polyester chain with different mass ratios.The morphology and structure of（MH-PBDA）_n were characterized by scanning electron microscopy（SEM）and Fourier transform infrared spectroscopy（FTIR）.The structure of（MH-PBDA）₇-co-PET was characterized by ¹H-NMR.The flame retardancy and mechanical properties of（MH-PBDA）_n-co-PET were investigated and its flame retardancy mechanism was explored.The results showed that the flame retardancy of（MH-PBDA）₇-co-PET was the best and reached V-0 level in UL-94 test.Compared with pure PET,the peak heat release rate,peak smoke production rate,peak carbon monoxide production rate and peak carbon dioxide production rate were reduced by 66%,44%,73%and 61%,respectively.3.MH-PA was prepared with magnesium hydroxide and phytic acid,and Fe-P was prepared with phosphite and ferric chloride hexahydrate.Three kinds of flame retardants MH-PA,Fe-P,diphenylsiladiol（DHDPS）and complex（MH-PA/DHDPS）and（Fe-P/DHDPS）were introduced into PET molecular chains,respectively.Co-polyesters were prepared.The morphology and structure of flame retardant were characterized by scanning electron microscopy（SEM）and Fourier transform infrared spectroscopy（FTIR）.The structure of intrinsic flame retardant PET was characterized by ¹H-NMR spectra.The flame retardancy and mechanical properties of intrinsic flame retardant PET were investigated and its flame retardancy mechanism was explored.The results show that the limiting oxygen index of（MH-PA/DHDPS）₅-co-PET is 29.1%and reaches V-0 grade.Compared with pure PET,the peak heat release rate,peak smoke production rate,peak carbon monoxide production rate and peak carbon dioxide production rate of DHDPS₅-co-PET decreased by 65.6%,72.4%,33.3%and 65.2%,respectively.