Preparation Of Graphite Nanosheets/Polystyrene Flame Retardant Materials And The Properties

Expandable Polystyrene(EPS)and Polystyrene(PS)have a wide range of applications in many fields,such as building insulation,electrical and electronics.Accompanied by the importance of property safety,PS and EPS flame-retardant performance requirements are getting higher and higher.Halogen-free flame retardant is the main direction of the flame retardant composits.Intumescent flame retardant(IFR)with high flame retardant efficiency and environment-friendly features have received great attention.In recent years,researchers have obtained some beneficial effects in the flame retardancy field by using graphite nanosheets(GNP,a novel carbon material with a lamellar structure and specific surface area)and intumescent flame retardant.However,The study of synergistic flame-retardant effect is not enough depth.Therefore,it is great significance to reduce the amount of flame retardant and improve the flame retardancy of the composites for studying the synergistic flame-retardant effect between GNP and IFR.In the dissertation,GNP/IFR/PF/EPS flame-retardant foams were prepared by the bead-coating method.GNP/IFR/PS flame-retardant composites were prepared by powder-mixing method and melt-mixing method.The cell size of the foams was measured by a polarizing microscope(RPM).The flame retardant properties were charactered by the limit oxygen index,the horizontal and vertical combustion test and the cone calorimeter test.The composition and the surface morphology of the material after burning charcoal were analysised by energy dispersive spectrometer(EDS)and scanning electron microscopy(SEM).Based on the above tests,the synergistic flame-retardant effect and flame retardant mechanism butween GNP and IFR in both EPS and PS materials were discussed.The GNP/IFR/PF/EPS flame retardant foam was prepared by bead coating method.The research on the cell size of the flame retardant foam shows that the amount of phenolic resin(PF)used in the coating has a significant effect on the foaming properties of the foam.When the PF content is less than 100 phr,the foaming property of the foam can be ensured.The results showed that the GNP/IFR/PF/EPS flame-retardant foams prepared by bead-coating method exhibited synergistic flame retardancy effect when the amount of IFR and GNP were 20 phr and 8 phr,respectively.The LOI of flame retardant foam was 24.7.When the amount of IFR was 40 phr and the amount of GNP was 4 phr and 8 phr,the flame retardant foams also showed the synergistic effect,the LOI were 25 and25.5,the level of combustion have reached HF-1 level.The results of combustion morphology showed that the introduction of GNP had a significant effect on the densification of the carbon layer of the flame-retardant foams.When the amount of GNP was too high or too low,the densified carbon layer was not conducive to the formation of the detonation layer.This may be attributed to the fact that when the amount of GNP is too low,the flame-retardant coating network in the material has not been formed.When the amount of GNP is too high,the thermal conductivity causes the wick effect.The IFR/PS and GNP/IFR/PS flame retardant composites were prepared by powder-mixing method respectively.The results of IFR/PS composite flame retardancy show that when the content of IFR with the ratio of APP and PER of1:1 is 30 wt.%,the LOI reaches 37.3 and the vertical burning reaches V-0 level.The effects of GNP on the flame retardancy of the composites were studied.The results showed that the composites exhibited great synergistic flame retardancy when the amount of IFR and GNP were 25 wt.% and 0.5 wt.%,respectively.The LOI of the composites was 36,the vertical combustion reached V-0 level and the burning carbon layer was dense and stable.