Phosphorous-contained Flame-retardant Thermal-tropic Crystalline Polyarylate Synthesis And Properties

In recent years, the haze pollution becomes the biggest environmental problem. One of thesolutions is decreasing the discharging of motor vehicle emissions, meanwhile filtrating high-temperature industrial waste gas and soot. At present, Polyphenylene sulfide (PPS) has been mostlywidely used in high temperature filtration material since it has good thermal stability. However, itshigh cost and dependence on import limited its application. Developing a kind of material becameparticularly important and attracted. Polyarylate with high performance of excellent mechanicalproperty and high temperature resistance is potentially suitable for this high temperature filtration.Unfortunately, with no hybrid element in its back bone, Polyarylate doesn’t meet the high demandof flame retardancy in the situation of dusty and arid. Molecular structure designing is necessary toimprove the flame retardancy of Polyarylate.In this thesis, Phosphorous-contained flame retardancy Polyarylate was synthesized with aceticanhydride, p-hydroxy benzoic acid (HBA),6-hydroxy-2-naphthalene formic acid (HNA),2-(6-oxido-6H-dibenz <c,e><1,2> oxaphosphorin-6-yl)-1,4-dihydroxy phenylene (DOPO-HQ) andterephthalic acid (TPA) by a two-step process including acetylation of monomer and in-situ meltingpolymerization. Its molecular structure, crystalline properties, thermal properties and flameretardancy was studied. Considering high melting viscosity and pyrolysis during the end-stage ofin-suit melting poly-condensation, Solid-State polymerization was applied for a higher molecularweight increasing. The influence of this processing on the molecular weight, crystallizationproperties, thermal properties and spinning properties was studied.(1) The structures of monomers which include acetylated monomers were characterized byFourier transform infrared (FTIR) spectroscopy and1H nuclear magnetic resonance (1H NMR)spectroscopy. It showed that the purity of all these monomer (HBA, HNA, DOPO-HQ and TPA)met the demand of copolymerization. The Acetylation of phenolic hydroxyl-contained monomerwas with high-efficiency and high yield.(2) The polymerization temperature, the catalyst and the ratio of monomers were determined by experiments. The phosphorus-contained co-Polyarylate was synthesized by meltingpolymerization. The chemical structure, molecular weight, crystalline properties and thermalproperties was characterized by13C nuclear magnetic resonance spectrum analysis (13C NMR),Fourier transform infrared (FTIR), melt index (MI), hot-stage polarizing microscope (POM), X-raydiffraction analysis (XRD) and differential scanning calorimetry (DSC). The Product belong to acategory of aromatic copolyester which obtained high molecular weight. Copolyester P-0has crystalform similar with hexagonal packing. The crystal form changed as the ratio of monomer from P-0to P-150, which also decreased the crystallinity of these copolyester. The highest crystallinity wasobtained by copolyester P-25which containing2.5mol%of DOPO-HQ. The melting points of thesecopolyesters were from244to280°C, with a trend of increasing first and then decreasing. All ofthese copolyesters have a good thermotropic liquid crystal properties on basis of excellent meltingorientation properties.(3) The flame retardant properties of phosphorous-contained Polyarylate were characterizedby thermo-gravimetric analysis (TGA) and limiting oxygen index (LOI) analysis. There are twomaximum decomposition stage of these copolyesters, with a starting temperature of379.2~435.7°C,a first maximum decomposition temperature of476.2~494.6°C and a second maximumdecomposition temperature of575.5~629.2°C. The char yield at700°C was7.45wt%. The flameretardancy of Polyarylate was significantly enhanced by DOPO-HQ, with a highest value of61.6%.The copolyester P-25have a LOI of47.0%which is14.4%higher than P-0.(4) The solid-state polymerization of the Polyarylate was carried out with a method of highvacuum and by-step heating processing. The influence of solid-state polymerization on theproperties of phosphorous-contained Polyarylate was studied by melt index (MI), polarizingmicroscope (POM), powder X-ray diffraction analysis (XRD) and differential scanning calorimetryanalysis (DSC). The melt index decreasing cooperating with texture changing of higher density ofmicro-domain and banded structure formed by copolyester P-25reveals that molecular weight ofcopolyester increased. The crystal was gradually improved, meanwhile a higher crystallinity wasobserved. The melting point of copolyester P-5increased from280to290°C which show the growthof molecular chain.Finally, Spinnability of copolyester P-25was explored by a double-cone miniature blendinstrument and it was found to be available in fiber-making.