Study On The Effect Of Intumescent Flame Retardant Form And Distribution Regulation On PBT Performance

In this paper,PBT-based flame retardant composites were prepared through twin screw extrusion and laminating thermal polymerization.the effects of the concentration gradient of flame retardants and layer thickness on the flame retardancy of PBT-based flame retardant composite system were studied.PBT flame retardant composite material of homogeneous dispersion and island distribution were prepared through twin screw extrusion and press vulcanizer.The effects of flame retardant homogeneous dispersion and island morphology on the flame retardancy and mechanical properties of PBT-based flame retardant composite system were studied.Flame retardant properties,thermal stability and mechanical properties of PBT/IFR flame retardant composites of homogeneous dispersion,layered concentration gradient and island distribution were characterized by UL-94 vertical combustion,limiting oxygen index(LOI),weight loss(TGA)and tensile test,respectively.Differential scanning calorimetry(DSC),scanning electron microscopy(SEM)and polarized light microscopy(PLM)were used to characterize the crystallization of PBT/IFR composites and the compatibility of different IFR distribution.Experimental results:1?The homogeneous dispersion PBT/IFR composites were prepared by homogeneous dispersion and PBT flame retardant modification using different ratios of IFR.The results of flame-retardant test showed that with the increase of flame retardant mass fraction,the flame retardancy increased gradually,but its mechanical properties decreased.The LOI increased from 21.5% to 27.1% and the UL94 level reached V0 when 40% IFR was added to PBT.The results of TGA and IR spectra showed that the addition of IFR was beneficial to the carbon layer formation of pure PBT,and when the content of flame retardant was 22.5%,PBT/IFR composites reached V0 grade and had the best comprehensive performance.2?A series of gradient gradient layered PBT/IFR composites were prepared by multilayer thermal composite method.SEM results showed that the IFR lamellar concentration gradient was distributed in the PBT/IFR composites,and the interface compatibility between the layers were good.The results of flame-retardant and mechanical tests showed that the smaller the difference in the concentration between layer and layer,and the multi-stage concentration gradient could improve PBT/IFR layered composite resistance compared with the same IFR mass fraction PBT/IFR composites combustion performance,delaying the combustion of the composite system,but also inhibiting the expansion of the whole system in the system,slowing down the decline in mechanical properties.The results of TGA showed that the IFR lamellar concentration gradient distribution had some influence on the thermal stability of the layered PBT/IFR composites.3?A series of island PBT/IFR composites were prepared by monolayer thermal composite method.SEM and PLM experiments showed that the IFR sea-islands were distributed in PBT/IFR composites,and the interfacial compatibility was well.The results of flame retardant and mechanical tests showed that the IFR distribution of PBT/IFR composites could improve the flame retardancy and reduce the mechanical properties of PBT/IFR composites compared with the equivalent IFR mass fraction homogeneous dispersion PBT/IFR composites.The results of TGA showed that the regulation and optimization of IFR island distribution contributed to regulating the thermal stability of PBT/IFR composites.