Preparation And Properties Of Organic Functionalized Metal Hydroxides And Intrinsic Flame-retardant Polyesters

Polyethylene terephthalate(PET)is an important thermoplastic polyester.Due to good thermal chemical stability,excellent spinnability and mechanical properties,it is widely used in all aspects of human life.Especially in the fields of textiles,electronic appliances,aerospace,etc.,it is the most widely used.However,PET is highly flammable and easy to produce droplets,which are fatal flaws that limit its wide application.Therefore,the use of flame retardants to impart flame retardancy to polyester is an effective way to solve the problem.In this paper,an organic functionalized inorganic flame-retardant material was designed and prepared to study its flame-retardant effect on polyethylene terephthalate.The specific content is as follows:(1)Phosphorus-aluminum base flame retardants(d HA)with different particle sizes were prepared by neutralization reaction of hydroxyl ethyldiphosphate(HEDP)with different particle sizes of aluminum hydroxide(ATH).The intrinsic flame retardant polyethylene terephthalate(d HAn PET)with different content of flame retardant was prepared by the esterification and polycondensation reaction of terephthalic acid(PTA)and ethylene glycol ester(EG)with d HA.The structures of phosphorus-aluminum-based flame retardants and copolyesters were characterized by Bollier transform infrared spectroscopy,X-ray diffraction,nuclear magnetic resonance and scanning electron microscopy.Cone calorimeter and oxygen index meter were used to investigate the properties of the intrinsic flame-retardant PET prepared.The results showed that the introduction of flame retardant improved the thermal stability of copolyester,in which 10HA₇PET copolyester showed the best thermal stability.The peak heat release rate(p HRR),total heat release rate(THR)and peak carbon monoxide release rate(p COPR)of 10HA₇PET copolyester decreased by 43%?33.2%and 41.5%,respectively;the limiting oxygen index(LOI)increased from 24.5%to 30.5%and UL-94 reached V-0 grade.(2)A new type of phosphorus-magnesium flame retardant(PM)was synthesized by the reaction of magnesium hydroxide(MH)and pyrophosphate(PPI).As a functional monomer,PM was grafted onto the chain of PET polymer by chemical reaction to prepare intrinsically flame retardant polyester;The structure and morphology of PM and intrinsic flame retardant polyester were characterized by Bollier transform infrared spectroscopy,X-ray diffraction,nuclear magnetic resonance and scanning electron microscopy.The flame retardant properties and mechanism of intrinsic flame retardant polyester were investigated by using UL-94 and cone calorimeter.The results show that PM₇PET copolyester exhibits excellent flame-retardant properties,its limiting oxygen index value reaches 30.5%,and UL-94 reaches V-1 level.Compared with pure PET,the peak heat release rate(pHRR),carbon monoxide(p COPR)and carbon dioxide peak release rate(p CO₂PR)decreased by 44.3%,?63.2%and 37.8%,respectively.(3)Surface modification(Sa)of magnesium hydroxide(MH)with sebacic acid produces a functional organic magnesium salt(SM),and SM is introduced into the PET chain through copolymerization to prepare intrinsic flame-retardant polyester;The structure and morphology of SM and intrinsic flame-retardant polyester were characterized by Bollier transform infrared spectroscopy,X-ray diffraction,nuclear magnetic resonance and scanning electron microscopy.Oxygen index tester,UL-94 and cone calorimeter were used to test the flame retardant properties of copolyester.The flame-retardant properties of copolyesters in the presence of only MH were investigated.The results showed that the peak heat release rate(p HRR),carbon monoxide release rate(p COPR)and peak carbon dioxide release rate(p CO₂PR)of SM₈PET copolyester decreased by 41.2%?71.1%and 32.5%,respectively.