Preparation And Properties Of Halogen-free Flame Retardant Polyethylene Foam

Foaming composites are materials with gas dispersion in solid phase. This kind of materials has a lot of advantages except for what the common plastics have, so polyethylene foaming composites are one kind with a large domain of application in industry and agriculture, science and technology and many areas in daily life. However, polyethylene can get fire very easily because of the lowest limited oxygen index in all kinds of plastics. And the LOI will get lower and lower with the density get smaller and smaller. But in nowadays protecting fire is a key problem. So it is very important to study the flame retardancy of polyethylene foaming composites.Several flame retarded polyethylene foam composites were prepared via mold compounding in one step. And the effect of all kinds of addition has been studied. BDP adding as plasticer could decrease the composites' melting point and improve the rheology obviously; coupling agent PE-g-MAH could improve the dispersion of inorganic agent in the organic phase; and the right amount of ADC and DCP were got.The apparent density, the bubble structure and the tensile strength were studied. The apparent density of the flame retarded polyethylene foaming composites was not very higher than the neat one, and there are not obvious changes on the shape of the bulk only with the wall getting thinner. Tensile strength and tensile ratio at brake were decreased a bit.The flame retardancy of the polyethylene composites were studied by cone colorimeter test and limited oxygen index. The results showed that the addition of the flame retardants improve the foaming composites' flame ability greatly in LOI, HRR, THR, MLR and TSR. SEM imagines of burnt sample in a CONE showed layers of porous carbon. FT-IR study of the residue showed the existence of double carbon bonds and phosphates which can change the route of degradation and reduce the production of burnable gases. The residuals after TGA testing and the activation energy of degradation were increased because of the addition of thermal expandable graphite and ammonium polyphosphate. The py-GC/MS results showed that there were not many differences but the flame retarded one product more circle alkyl because of bridge linkages. So we could draw a conclusion that the flame action mainly happened in solid phase.