Preparation And Properties Of Flame Retardant Modified Polyester

Polyethylene terephthalate(PET)is a widely used material,which is very common in people's lives such as clothing and plastic bottles.PET has excellent performance in many aspects,because it is extremely easy to burn,it limits its application in the field of closed environment and high-rise indoor textiles.Therefore,it becomes very important to modify the flame retardant properties of PET.In this paper,the copolymerized phosphorus flame retardant 2-carboxyethyl phenyl hypophosphorous acid(CEPPA)is used as the flame retardant modifier,which is pre-esterified with ethylene glycol and then copolymerized to the PET macromolecular chain through polycondensation reaction.The flame retardant polyesters with different phosphorus content were obtained,and the pretreatment process of flame retardant CEPPA was compared and analyzed.The esterification conversion rate and thermal stability of flame retardant CEPPA,as well as the color value and intrinsic viscosity of different flame retardant polyesters The basic properties such as the concentration of carboxyl groups and the concentration of diethylene glycol were tested and analyzed,and the effects of different catalysts on the polymerization process and flame retardant properties of flame-retardant polyester were compared.Finally,the best polymerization process and catalyst were selected to obtain different phosphorus The mass fraction of flame-retardant polyester was characterized by its structure and performance using FT-IR,WAXD,TG,DSC,capillary rheometer and vertical combustion test.The main conclusions are as follows:1.Through TG analysis of CEPPA monomer,the initial decomposition temperature of CEPPA is 231°C,while the esterification temperature of PET polymerization is about 230°C,so CEPPA must be esterified separately at low temperature.After adopting the low-temperature esterification process,the polycondensation time of the polyester with the same phosphorus mass fraction was significantly shortened,the stirring power was higher,and the obtained flameretardant polyester had a higher intrinsic viscosity,and no experimental failure occurred.Comparing the CEPPA esterification solution prepared under different reaction conditions,it is found that the esterification reaction temperature and reaction time will affect the conversion rate of CEPPA esterification reaction.The CEPPA esterification solution prepared by reacting at 190°C for 3 hours has a high conversion rate.The thermal stability is the best.CEPPA participates in the copolymerization reaction should adopt low-temperature esterification process.2.Select three catalysts of titanium glycol,supported titanium catalyst and antimony trioxide to copolymerize into a flame-retardant copolyester with a phosphorus mass fraction of 0.60%.Compare the color value,intrinsic viscosity,and viscosity of different flame-retardant polyesters.The end carboxyl group concentration shows that the color value of Sb-PET using antimony catalyst is significantly better than that of Ti-PET using titanium catalyst.The polycondensation reaction time of the two types of Ti-PET is longer than that of Sb-PET,but the intrinsic viscosity of Ti-PET is lower than that of Sb-PET.The titanium-based catalyst also has a strong promotion effect on the reverse reaction of the polymerization reaction.Flame-retardant polyesters using titanium-based catalysts have a higher melting point and weaker crystallization ability.The analysis of the combustion experiment shows that different catalysts will not have a greater impact on the limiting oxygen index and vertical combustion grade of flame-retardant polyester.In comprehensive comparison,antimony trioxide catalyst should be used to prepare flame-retardant polyester.3.Flame-retardant polyesters with different phosphorus contents were prepared by pre-esterification process,and various aspects of the performance of flameretardant polyester were analyzed by means of FT-IR,WAXD,TG,DSC,capillary rheometer and vertical combustion test.Tests show that: CEPPA exists in the polyester macromolecular chain structure.The crystalline properties of polyester have been improved,but the crystal structure of PET has not changed.The introduction of CEPPA increased the ?T of the PET material and reduced the crystallization rate of the material.The melting point of the flame-retardant polyester decreased with the increase in the amount of CEPPA added.The TG test showed that the thermal stability of the polyester was reduced after the introduction of CEPPA,but as the amount of CEPPA increased,the amount of residual carbon in the flame-retardant polyester increased.Shear rheological performance tests show that the flame-retardant polyester prepared is still a pseudoplastic fluid,but the non-Newtonian properties of flame-retardant polyester melt are reduced to a certain extent compared with pure PET.The combustion experiment shows that after adding flame retardant,the higher the phosphorus mass fraction of the flame-retardant copolyester,the better its flame retardant performance.When the phosphorus mass fraction is 0.55%,its LOI value has reached 28%,which is vertical The combustion level reaches V-0,and the flame retardant performance is excellent.