Halogen-Free Flame Retardant Modification Of ABS And Its Mechanism

In this paper,Halogen-free flame retardant ABS was prepared by mechanical blending.The effects of different phenolic resins(unvulcanization PF2123,vulcanization PF201,vulcanization PF2402),phosphates(triphenyl phosphate(TPP),bisphenol-A bis(diphenyl phosphate)(BDP),isopropylphenyl phosphate(IPPP)),novolac epoxy resins(ECN,EPN)and encapsulated red phosphorus(conventional type,whiteness type)on mechanical properties,processability and flame retardancy were discussed.The theoretical model of the interaction between phosphates and PF during combustion was studied by scanning electron microscopy(SEM)and fourier transform infrared spectrometer(FT-IR).FDS fire simulation software was used to simulate and predict the oxygen index and the vertical combustion testModification of ABS by adding different PF.The results showed that the toughness of the system obviously decreased with the addition of unvulcanization phenolic resin.Vulcanization phenolic resins could obtain higher notched impact strength by vulcanizing the rubber phase in ABS.Moreover,the benzene ring structure introduced after the reaction of vulcanization phenolic resins with rubber phase could improve the thermal stability of the rubber phase and greatly increase the oxygen index of the system.The mechanical properties of PF2402 system were better than that of PF201 system.The flame resistance of PF201 system was higher than that of PF2402 system.Considering the notched impact strength and oxygen index,the best PF chooses PF2402 and the best dosage is 7%.Flame retardant ABS was prepared by different phosphates.The results showed that the notched impact strength of the system decreased gradually with the addition of phosphates.The melt flow rate increased gradually.The oxygen index increased and then decreased under the influence of physical interference of phosphates(grid broken).The notched impact strength of BDP system was better than that of TPP and IPPP system.The melt flow rate of IPPP system was the highest.The chemical interference(grid crack)property of TPP was the smallest The oxygen index of the system was the highest In addition,other properties are between BDP system and IPPP system.Considering notch impact strength,melt flow rate and oxygen index,TPP is the best phosphate and 11 phr is the best dosage.Added novolac epoxy resins and encapsulated red phosphorus made the comprehensive performance of the flame-retardant ABS optimal.The results showed that the notched impact strength is 11.13KJ/m2 when the ECN content is 5 phr.The melt flow rate was 74.25g/10min.The oxygen index was 32.8%.The vertical combustion was gradeless.The notched impact strength of the system was 10.94 KJ/m2.The melt flow rate was 39.34 g/10 min.The oxygen index was 25.5%.The V-0 grade of vertical combustion was obtained when the addition of red phosphorus was 8 phr.Fire simulation results showed that oxygen index(LOI)test and vertical combustion(UL-94)test had different flame combustion status.Among them,the flame in LOI test was "slow fire" and the flame in UL-94 test was "fast fire".Combined with simulation and the data of degradation activation energy.The degradation activation energy(Ea)had the following relationship with LOI and UL-94 under certain conditions(1.Fire retardant is mainly condensed phase.2.Fire retardant has no special reaction with base material).When percent conversion(a)>50%,Ea of fire retardant>Ea of base material,it was considered that the fire retardant could enhance the LOI of the material.However,Flame retardants had limited help for UL-94.When a<50%,Ea of fire retardant>Ea of base material,it was believed that the fire retardant could enhance UL-94 of materials.Besides fire retardant was helpful for LOI at a certain extent.When the Ea of fire retardant was always larger than the Ea of base material,it was considered that the fire retardant could improve both LOI and UL-94.When the ?Ea was small,the flame retardant efficiency was low and required a large amount of additions.When ?Ea was large,the flame retardant efficiency was high and could add a small amount of additions.