| Vinyl ester resin(VER)and Polylactic acid(PLA)are increasingly used in our daily life due to their superior properties.However,the traditional VER and PLA are highly flammable,which greatly limits their applications in some areas with flame-retardant requirements.Therefore,enhancing the flame-retardant performance of VER and PLA have a important practical significance in broadening its application range.This paper mainly uses the polyphosphate flame retardant MODOP and ammonium polyphosphate(APP)or montmorillonite(MMT)to add VER and PLA matrix,respectively,to investigate the flame retardant modification.Some tests results and analysis as follows:MODOP compound APP or MMT is used to fill VER,further to achieve flame retardant modification of VER.The results of the limited oxygen index(LOI),the vertical burning test(UL-94)and thermogravimetric analysis(TGA)indicated that the flame retardant performance of VER was significantly improved compared with that of pure VER due to the addition of MODOP,MODOP/APP and MODOP/MMT.However,by comparing the three flame retardant systems,MODOP is suitable to be directly added into VER to improve the flame retardant performance of VER material.Among then,the LOI value of 20%MODOP/VER is 23.5%,and V-1 rating was achieved in UL-94.MODOP compound APP or MMT is added to VER to promote the carbon formation of VER materials.At 700?,the carbon residue of20%MODOP/APP/VER and 20%MODOP/MMT/VER is 54% and 52.9%higher than that of 20%MODOP/VER system,respectively.Effectively improve the thermal stability of VER material.The flame-retardant modification of PLA was studied by MODOP and MODOP combined APP or MMT.The experimental results indicated that MODOP,MODOP combined with APP or MMT can improve the flame retardancy of PLA composites compared with pure PLA materials.However,compared with the three flame retardant systems,MODOP combined with MMT can improve the flame retardancy of PLA materials.The LOI value of 1.9%MODOP/PLA and 1.9%MODOP/MMT/PLA were26.6% and 28.5%,those of systems all obtained the V-0 UL-94 rating.CONE test results showed that MODOP and its MODOP combination APP or MMT could effectively reduce the Pk-HRR,THR and TSP of PLA material,and effectively improve the fire safety of PLA materials.Scanning electron microscopy(SEM)analysis revealed that MODOP combined with MMT made MODOP more evenly dispersed in PLA.Raman spectroscopy,X-ray photoelectron spectroscopy(XPS)and thermogravimetric infrared(TGA-FTIR)showed that APP acted as gas source and acid source when MODOP combined with APP in PLA matrix,it also play a coordinating flame retardant role with MODOP.And synergistic effect of MODOP and MMT resulted in better dispersion of MODOP in PLA matrix.MODOP materials such as thermal decomposition to produce metaphophate make PLA material got behind in charcoal burning surface to form a layer of dense carbon layer,through the formation of higher graphitization degree of carbon layer to prevent the transmission of heat in the PLA matrix and flammable and exchange,thus increased the flame retardant properties of PLA materials,playing a crucial role in both the gas phase and the condensed phase of the composites flame retardant effect.In conclusion,the flame retardant effect of MODOP in PLA is better than in VER.The flame retardant effect of MODOP and MODOP combined MMT systems on PLA materials was better.The LOI values of1.9%MODOP/PLA and 1.9%MODOP/MMT/PLA systems increased from 15.4% to 26.6% and 28.5%,respectively.The UL-94 rating was also upgraded from no rating for the pure PLA to V-0 rating.At the same time,the addition of MODOP and MODOP/MMT to PLA material effectively improves the smoke suppression performance of PLA material.By increasing the generation of melt dripping,PLA material can achieve the effect of self-extinguishing during combustion,and by generating high-quality graphitized carbon layer,further improve the flame retardant performance of PLA material. |
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