Preparation And Characterization Of A Ceramizable PE Composite Material With High Flame Retardancy

Polyethylene material（PE）is widely used because of its wide source,large output,easy processing,low price,relatively high mechanical properties and solvent resistance;but polyethylene material is extremely easy to burn,and a large amount of heat will be released during combustion,which greatly increases the possibility and danger of fire.In this paper,a ceramizable PE composite material with high flame retardant properties was prepared by adding appropriate fluxes,porcelain fillers and intumescent flame retardants to PE,which had both properties of PE and excellent high temperature resistance of ceramic materials.In the preparation of ceramicized PE composites,we first compared the effects of glass powder GP45,GP50 and zinc borate on the performance of PE composite materials after high temperature ablation.Through performance analysis,GP50 was determined as the fluxing agent of PE composite material.Then the influence of the ratio of GP50 to ceramic filling mica powder（MP）and their addition amount on the properties of PE composites was studied.It is found that when the ratio of GP50/MP was 1:1,the composite had the best performance after high temperature ablation.With the increase of the amount of GP50/MP,the properties of the ablated PE composites improved slightly,but the mechanical properties of PE composites decreased at room temperature.Infrared spectroscopy（FTIR）,polarized light microscope（POM）,X-ray diffraction analysis（XRD）and scanning electron microscope（SEM）were used to analyze the ceramization process and mechanism,and it was found that as the temperature increased,the internal pores of the ablated PE composite material became smaller,the structure became denser,and the eutectic reaction occured at 800℃and above.In order to effectively improve the flame retardant properties of PE materials,a series of intumescent flame retardants（IFR）were added to PE.The vertical combustion test（UL-94）and the limiting oxygen index（LOI）were used to analyze flame retardant efficiency.Two formulations with the best flame retardant performance were obtained,IFR-1-TMG and IFR-2-TMG.UL-94 grade and LOI of PE composite with 35 wt%IFR-1-TMG were V-0 and29.4%respectively.UL-94 grade and LOI of PE composite with 35wt%IFR-2-TMG were V-0and 28.8%respectively.Cone calorimeter analysis and thermogravimetric analysis（TG）results showed that the addition of IFR could effectively inhibit the combustion of PE,reduce the peak heat release rate（PHRR）and total heat release（THR）,and improve the thermal stability of the material.Scanning electron microscope（SEM）was used to analyze the surface morphology of the combustion residues.It was found that dense carbon layers were formed on the surface of the combustion residues,which was the main reason for the improvement of flame-retardant performance of PE.The effect of the ratio of IFR and GP50/MP_1:1on the performance of PE composites was explored.without IFR,PE composites had no flame retardant propertity and there was dripping during the combustion process.Comparingly,the UL-94 rating and LOI of PE composite with25wt%IFR-1-TMG and 35 wt%GP50/MP_1:1reached V-0 and 27.2%respectively,and there was no droplet phenomenon.The results of TG,XRD and SEM analysis showed that after adding IFR,a dense carbon layer was formed on the surface of the ablated composite at high temperatures.However,the addition of flame retardant had a negtive effect on the ceramic process of the PE composite because the flame retardant hindered the flow of glass powder at high temperature and inhibited the eutectic reaction.