Study On Flame Retardancy Of POM With CeO₂ Compound Expansion Flame Retardant System

Polyoxymethylene(POM),as one of the five commonly u sed engineering plastics,has a limiting oxygen index of only 15%and is extremely flammable,which greatly affects the application range of the material.Therefore,it is necessary to study the flame retardant properties of the material.In this paper,the flame retardant research of POM materials is mainly based on the types of flame retardants,the amount of flame retardants added,the composition of flame retardants and the particle size and content of the synergistic flame retardant cerium oxide(CeO₂).The prepared splines were characterized by methods such as LOI,UL-94,SEM,TG-DSC,FT-IR,CONE,etc.The main research results obtained are as follows:1.The effect of CeO₂ content and particle size on the flame retardant properties of POM materials was studied,and the results showed that CeO₂ can have a certain effect on the flame retardant properties of POM materials.When the concentration is 1%CeO₂ and the particle size is 1?m CeO₂,the flame retardant performance of POM is the best,and the oxygen index reaches 20%,but the mechanical properties are greatly affected.2.Six modifiers of SA,PEG,SDS,SLS,KH550 and KH570 were selected to modify CeO₂ to solve the agglomeration phenomenon of CeO₂.Tests show that these six modifiers have a certain degree of modification effect on CeO₂,among which the activation index of SLS-CeO₂ rises to 91%,the effect is the best.Among the POM splines prepared with it,SLS-CeO₂ has the best flame retardant performance.The modified CeO₂ can effectively delay the decomposition temperature of the spline.3.The APP/DAP/CS is compounded through orthogonal experiments.The experimental results show that the addition of APP/DAP/CS system can effectively improve the flame retardant performance of POM,the LOI can be increased from 15%to 38%,and the combustion level is increased from no level.To V-1.But the mechanical properties are only 50%?60%of pure POM,which is greatly reduced.When APP:DAP:CS=4:3:1,the flame retardant performance reaches 38%,and the flame retardant effect is the best.With CeO₂ as a synergistic flame retardant,the LOI of the CeO₂/IFR/POM composite material prepared floats between 29%and 41%.When 1%CeO₂/IFR/POM,the sample has the best flame retardant performance,and its LOI reaches 41%,vertical combustion grade V-0,while the flame retardant performance is improved,its mechanical properties will also cause a certain degree of decline.Taking SLS-CeO₂/IFR/POM as the compound intumescent flame retardant system,research shows that:1%SLS-CeO₂/IFR/POM has the best flame retardant performance,the oxygen index is as high as 44%,and the vertical combustion grade is V-0 When the content of SLS-CeO₂ gradually increases,the flame retardant properties of POM materials decrease.Compared with CeO₂,the mechanical properties of the splines prepared by the addition of SLS-CeO₂ are improved.The carbon layer produced by SLS-CeO₂/IFR after burning is compact and has no pore size,which plays the best role of insulation.The initial weight loss temperature of the sample is delayed,the amount of carbon residue is also increased,the ignition time of the material is also effectively delayed,and the peak value of heat release rate is also decreased,which indicates that the burning carbon layer effectively insulates the flame and heat,prevents the material from continuing to burn,shortens the burning time and improves the flame retarda nt performance of POM materials.