The Preparation And Characterization Of Phosphorus Flame Retardant Copolyester And Fiber

Polyester(PET)has been widely used in the fields of fiber,plastic and film because of its high strength and modulus,good elasticity and thermal stability,excellent chemical resistance.However,as the limiting oxygen index of polyester is about 21%,the combustibility and melt dripping during the combustion process greatly limit its applications.Therefore,the studies on flame retardant polyester and melt dripping resistance have attracted considerable attention.In this thesis,a series of flame retardant copolyesters were synthesized via-copolymerization reaction by using phosphorus flame retardant CEPPA as the third monomer.The sequence composition and crystallization property were characterized by means of NMR and DSC.Flame retardant copolyesters/P-glass nanocomposite materials were prepared by in situ polymerization reaction and blending method respectively.The effects of the P-glass content on the structure and morphology of the nanocomposite materials were also investigated.In addition,the liquid coloring flame retardant copolyesters were prepared and a preliminary study on their spinnability has been performed.The main results obtained are as follows:1.The effect of flame retardant CEPPA on the condensation polymerization reaction was investigated in this thesis.It could be found that the introduction of flame retardant caused the decreasing of the time and temperature of the polymerization reaction.The chemical composition,sequence distribution,crystallization property,phosphorus content and limiting oxygen index of the flame retardant copolyesters were characterized by means of NMR,DSC,TG,elemental analysis and limiting oxygen index test.The results showed that the majority of CEPPA units are copolymerized into the polyester chains in a form of random distribution;small part of CEPPA units were in a form of short segment in the polymer chains,and the random coefficient of the copolyester decreased as the flame retardant contents increased.Compared with PET,Tg,Tm and the crystallinity of the flame retardant copolyester decreased,which was ascribed to the decline of the regularity of the copolyesters chains.The addition of flame retardant CEPPA enhanced the maximum decomposition temperature;widened the range of thermal decomposition temperature.Moreover,the sample decomposition residual quality and limiting oxygen index values also increased with the increase of the flame retardant content,as the phosphorus content in the flame retardant copolyester is 9.08mg/g,the limiting oxygen index value can be more than 33%.2.Flame retardant copolyesters/P-glass nanocomposite materials were prepared by in situ polymerization reaction.The results showed that a small amount of P-glass could increase the viscosity of melt fast and significantly during the polymerization stage,which led to the lower molecular weight of the products.SEM micrographs showed that the P-glass are dispersed uniformly in the polymer matrix and formed a three dimensional network structure.3.Flame retardant copolyesters/P-glass nanocomposite materials were also prepared via blending method.The structures and properties of the nanocomposite materials were characterized by means of SEM,DSC,WXRD,TQ limiting oxygen index test and vertical combustion test.SEM micrographs show that when the P-glass content is more than 10%,the P-glass particles with size in the range of 50nm to 100nm were dispersed uniformly in the flame retardant copolyester matrix.This is due to the fact that P-glass has lower Tg and exists in the form of liquid state during the blending process.When the P-glass content is more than 20%,they tend to form a three dimensional network structure.When the P-glass content is less than 10%,the crystallinity of the composite material increased as the P-glass particles acted as nucleating agents.When the P-glass content is more than 20%,the crystallinity of the composite material decreased,which was ascribed to the network structure of P-glass hindering the regular arrangement of the polymer chains.Moreover,the limiting oxygen index of the flame retardant copolyesters/P-glass nanocomposite materials enhanced as increasing the P-glass content,and the melt dripping resistance improved effectively.The materials have excellent flame retardant property with FV-0 level for the vertical combustion test.4.Liquid coloring flame retardant copolyester was prepared by liquid coloring technology,and the spinnability of the liquid coloring flame retardant copolyester was also studied.The research results showed that liquid coloring flame retardant copolyester had a good spinnability.The results of DSC,TG and limiting oxygen index test showed that the effects of dyes on the crystallization properties and thermal stability properties of flame retardant copolyester are negligible.Moreover,the liquid coloring flame retardant copolyester showed a good flame retardant performance.The thermal shrinkage of the liquid coloring flame retardant copolyester fibers decreased,and the dimension stability improved.