Property Of Flame Retardant Polyolefin Composites With Two Dimensional Inorganic Fillers As Synergist Of Magnesium Hydroxide And Flame Retardant Mechanism

Magnesium hydroxide(MH)is one of the important inorganic flame retardants conforming to the environment friendly,low carbon cycle,sustainable development direction,and is a key raw material used in wire making to require halogen free flame retardant polyolefin materials.In order to meet the diverse requirements of fire safety and thermal management for cable carrier brought forward by the development of energy and information technology,polyolefin composites with MH flame retardant are facing the double challenges of low flame retardant efficiency and poor thermal conductivity.BN and GNP were used as two-dimensional inorganic fillers(Nano).Polycarbosilane(PCS)and polysiloxane(PSO)were used as silicone-containing synergistic flame retardant components(Si).MH was used as the main flame retardant,and LDPE,EVA and POE were used to form the polyolefin matrix(PO).The flame retardant properties of three systems,PO/MH/Nano,PO/MH/Si and PO/MH/Si/Nano,were investigated.The results of oxygen index(LOI)and vertical combustion studies showed significant synergistic flame retardancy between MH/Nano,MH/Si and MH/Si/Nano.BN and GNP significantly increased the LOI of the composites and improved the UL-94 rating.cone combustion behavior studies revealed the inhibitory effect of two-dimensional inorganic fillers on heat and smoke release behavior.BN reduced the p HRR,THR and TSP of PO/MH/PCS by 16.6 %,16.6 % and 46 %,respectively,and GNP reduced the pHRR of PO/MH/PCS and TSP by 9.8 % and 54 %,and carbon residues by 5.2 %.The thermal degradation process and carbon layer structure of the composite were studied by TG,XRD,FTIR and SEM.The results showed that the surface migration of the two-dimensional inorganic filler and the thermal oxidative degradation of the silicon-containing polymer on the surface are two processes that promote the formation of the cohesive phase carbon layer,and the dense and continuous surface structure of the carbon layer and the rich internal pore structure make it have a good barrier effect,which is an important factor in the mechanism of the flame retardant effect of the cohesive phase.The interaction of two-dimensional inorganic fillers and MH is able to improve the thermal conductivity of composites,and halogen-free flame retardant polyolefin composites with better fire safety behaviors can be obtained by utilizing two-dimensional inorganic fillers synergistically flame retardant MH system.