Studies On The Synergistic Catalytic Carbonization And Flame Retardant Of PE And PP With Ni-Mo Catalysts

Catalytic carbonization can effectively deposit the carbon elements of the polymer to form the carbon layer to achieve the purpose of flame retardant.This new flame retardant method has attracted wide attention in recent years.PE and PP are the main polyolefin materials,which consist of carbon and hydrogen elements.Due to its structural characteristics,it is difficult for conventional flame retardants to be efficient flame retardants.Finding new and efficient carbonization catalysts for catalytic carbonization flame retardant is one of the important ways to solve the flammability of PE and PP.Based on previous research,this study explored the catalytic carbonization proformance and flame retardant proformance of nickel molybdenum bimetallic supported catalysts(Ni-Mo/MgO)and synergists for PE,PE/polylactic acid(PLA),and PP.In this dissertation,the flame retardancy of catalytic carbonization by adding Ni-Mo/MgO catalyst and different types of carbon black to PE was studied.The results show that carbon black can greatly improve the catalytic performance of Ni-Mo/MgO,especially acetylene carbon black.When 5 wt%Ni-Mo/MgO and 5 wt%acetylene black were added,the carbonization rate of PE at 700℃and 900℃reached 34%and 59%,respectively.The value of peak heat release rate(PHRR)decreased by 86%and 55%compared with pure PE and PE/Ni-Mo/Mgmaterials,respectively.Total heat release rate(THR)decreased by 43%and38%,respectively.These results show that the combination of Ni-Mo/MgO and acetylene black can effectively catalyze the carbonization of PE and achieve the purpose of flame retardant under the condition of strong flame.However,limiting oxygen index(LOI)test results showed that the catalyst could not effectively improve the LOI value of the material.This indicates that the catalytic performance of PE carbonization at low temperature is low.In this dissertation,the catalytic carbonization and flame retardant properties of PE composites with PLA were studied in the presence of carbon black and Ni-Mo/MgO.PLA is not only a dispersive accelerator of catalyst,but also a component of composite material.The effect of adding carbon black and Ni-Mo/MgO on the catalytic carbonization performance of PE/PLA system was studied,and the effect of carbon black and Ni-Mo/MgO on the catalytic carbonization flame retardant performance of polymer with the increase of PLA mass fraction in the system was studied.The results show that when adding Ni-Mo/MgO and carbon black respectively,it is found that Ni-Mo/MgO@carbon black system can also effectively catalyze the carbonization of PE/PLA and achieve flame retardant.When the mass fraction ratios of Ni-Mo/MgO and carbon black are 5:5,and the mass fraction ratios of PE and PLA are 60:30,the carbon formation and flame retardant properties of the polymer are the best.The carbonization rates at 700℃and 900℃are 34.2%and 50.7%,respectively.Meanwhile,the PHRR,THR and total smoke release(TSR)during combustion were reduced by 75%,23%and 65%,respectively,compared with pure PE/PLA materials.The mechanism study showed that adding carbon black could help catalyze PE/PLA to produce high graphitized carbon materials.The third part studied the catalytic carbonization flame retardancy of PP by Ni-Mo/MgO combined with conventional flame retardants(aluminum hydroxide ATH).The results show that ATH can improve the catalytic performance of Ni-Mo/MgO to the greatest extent when adding 5 wt%Ni-Mo/MgO and 50 wt%ATH.The charring rates of PP at 700℃and 900℃reached 32.7%and 57.5%,respectively.The value of the limited oxygen index(LOI)of PP composite reached 27.8%.At the same time,the initial thermal degradation temperature of PP was increased from 355℃to 447℃,PHRR decreased from 1271 k W/m~2 to 270 k W/m~2,THR from 219 MJ/m~2 to 96 MJ/m~2,TSR from 1429 m~2 to 114 m~2/m~2.In addition,the mechanical test results show that when Ni-Mo/MgO and ATH are added together,the mechanical properties of PP are improved compared with that of catalyst alone.