Study On Halogen Free Flame Retardant Poly (Trimethylene Terephthalate)

With the continuous development of world economy and science and technology,polymer materials have been developed rapidly.It has been used more and more widely in people's daily life and industrial production.However,most of the polymer materials are flammable,and pose a threat to people's personal and property safety;the scope of application of polymer materials has been greatly restricted.Therefore,it is of great significance to study the combustion characteristics and fire protection technology of polymer composites.Poly(trimethylene terephthalate)(PTT),as a new type of polyester material,has been paid more and more attention.However,the flammability of PTT greatly limits its application.In order to improve the flame retardancy of PTT resin and improve its application value,it is necessary to study its flame retardancy.Halogen free flame retardant has been widely used because of its low smoke,low toxicity and other environmental friendly characteristics,and it has gradually replaced the halogen flame retardant,which has become the most concerned flame retardant system.In this paper,the use of intumescent flame retardant EPFR-300 A,nitrogen flame retardant melamine cyanuric acid(MCA)and phosphorus flame retardant aluminium diethyl phosphinate(ADP),blending by twin screw extruder,study on the flame retardant modification of PTT.In the early stage of the experiment,because of the addition of flame retardant,the mechanical properties of PTT materials were decreased,cracks appear on the surface of the spline which produced by using the injection molding machine and the flat plate vulcanizer,unable to test.So it is necessary to use maleic anhydride grafted polyolefin elastomer(POE-g-MAH)and polyolefin elastomer(POE)to modify the PTT resin,and then to study the flame retardant modification of PTT.By comparing the mechanical properties of the PTT material,the best toughening agent and the optimal addition amount were determined.The results show that the toughening agent POE and POE-g-MAH can increase the mechanical properties of PTT resin,when the mass fraction of the same,the toughening effect of POE-g-MAH on PTT resin is better than POE.When the mass fraction of POE-g-MAH is 7%,the best comprehensive mechanical properties.EPFR-300 A,MCA and ADP were used as flame retardant modifier to modify the PTT resin.The effects of toughening agent and flame retardant on the flame retardancy,thermal properties and mechanical properties of PTT resin were studied by thermogravimetric analyzer(TGA),scanning electron microscopy(SEM),differential scanning calorimetry(DSC)and mechanical properties.The flame retardant mechanism was discussed by means of SEM,EDS spectroscopy and thermogravimetric analysis(TG-IR).The flame test results show that the toughening agent adding the same mass fraction,when the mass fraction of EPFR-300 A reaches 20%,the mass fraction of MCA reaches 20% and the mass fraction of ADP reaches 10%,the flame retardancy of PTT material is the best,the limiting oxygen index(LOI)reached 28.0%,24.9% and 30.0%,the vertical flame retardant grade reached UL94 V-0 level.The mechanical properties of the flame retardant PTT composites decreased,but the tensile strength and flexural strength of the composites were not changed,and the application of PTT resin was not affected.EPFR-300 A and ADP had good compatibility with PTT resin,but the compatibility of MCA and PTT was poor.The research of flame retardant mechanism showed that,EPFR-300 A is useful in flame retardancy primarily through the generation of inflated carbon layers in condensed phase.MCA play a role in flame retardancy mainly by creating large quantities of gases in gas phase,the function of ADP in flame retardancy mainly because of the produce of free radical scavengers and compact carbon layers in gas phase and condensed phase,respectively.Finally,5% mass fraction of ADP flame retardant,10% mass fraction of MCA flame retardant and 1% PTFE as an anti dripping agent were mixed to flame retardant modification of PTT resin,mechanical properties and flame retardant of the composites were tested to study the synergistic flame retardancy of two kinds of flame retardants.The experimental results show that the limiting oxygen index(LOI)is up to 26.9%,and the flame retardant grade of vertical combustion reaches UL94 V-0 grade.The flame retardant performance is better than adding MCA flame retardant and the mechanical properties is better than adding ADP flame retardant,compared to the high price of ADP flame retardant,in the mixed flame retardant system to ensure its flame retardant properties and mechanical properties at the same time,greatly reduces the cost of application.