Preparation And Characterization Of Environmentally-friendly Flame-retardant Polystyrene And Its Application In XPS Foam

Polystyrene(PS)is inherently extremely flammable.Because the structure of the molecular chain will produce black smoke when burned,its limiting oxygen index is only 19.6%.XPS is a foam sheet formed by extrusion molding of PS resin.Its limiting oxygen index is only 17%.Expandable Graphite(EG)is a new type of flame retardant,but the weak binding force between the expanded carbon layer formed by the heat of EG and the matrix leads to the weakening of the strength of the carbon layer.This severely weakens the flame retardant properties of EG in the polymer matrix.However,when the expandable graphite and the microcapsule red phosphorus(MRP)are used in combination,the flame retardant efficiency and the carbon layer strength are higher.This paper is divided into the following three parts:Firstly,a synergistic flame-retardant system composed of DBDPE and Sb2O3 was used as a flame retardant for polystyrene(PS),and the flame-retardant compound was prepared by melt-blending using an internal mixer.Material PS,and explore the flame-retardant synergistic effect of Br-Sb flame retardant at different ratios.The results show that there is a good synergistic effect between DBDPE and Sb2O3.The addition of Br-Sb flame retardant significantly improves the thermal stability and flame retardancy of PS.When the mass ratio of PS/Br+Sb is 83/17(the mass ratio of Br/Sb is 17/3),the flame retardant properties of PS composites are best,and the UL-94 test reaches V-0 level,LOI up to 30.1%.In terms of mechanical properties,the addition of Br/Sb flame retardants has little effect on the impact strength of the material.Then,the expandable graphite was coated with TEOS to prepare microcapsule expandable graphite(MCEG),and MCEG and MRP were used as synergistic flame retardants in the polystyrene matrix.The SEM and FTIR data were used to obtain the TEOS coating on the EG surface.Afterwards,the optimal formulation of the compounding system was explored using orthogonal experiments with three factors and three levels,and the best formula was PS/14MCRG/8MRP.Afterwards,the optimal formulation of the compounding system was explored using the orthogonal experiment of three factors and three levels.The best formula was PS/14phr MCRG/8phr MRP.The result of carbon residue FTIR analysis of the formula at different temperatures showed that:The silicon-containing group in the composite after 400 ? promotes the polymer to form a more stable carbon layer,which provides a better barrier effect.The above results show that MCEG can significantly improve the polymer combustion performance.Finally,in order to further improve the carbon layer strength of the composite,tripropyl isocyanurate(TAIC)was added to the EG/MRP and MCEG/MRP systems.Through the TGA,LOI,UL-94,CONE test found that the addition of TAIC can further improve the flame retardant behavior of the compounding system,carbon layer strength.And can greatly enhance the smoke suppression effect of the system.The formulation of the final foaming experiment was then determined.Supercritical carbon dioxide was used as the foaming agent to perform the foaming experiment on the flame retardant system.It was concluded that the PS/MCEG/MRP/TAIC foam has higher resistance than the pure PS foam.The flammability,carbon layer strength,smoke emission,heat insulation effect is good,and due to the addition of MCEG,the compound system is a micro-foam structure with better mechanical properties.