Facile Preparation Of Organic Modification Of Magnesium-Aluminum Hydrotalcite And Their Flame Retardant Properties

Polypropylene?PP?is widely used in industry and life because of its advantages of low cost,low toxicity,light corrosion resistance,good comprehensive mechanical properties,good electrical performance,easy processing and easy recycling.However,PP is extremely flammable and burns with a large number of droplets,which greatly limits the range of PP use,so it needs to be flame retardant.Based on human health and environmental protection,research on low-smoke and halogen-free flame retardants has received more and more attention,especially as inorganic halogen-free flame retardant materials.Magnesium-aluminum hydrotalcite?MgAl-LDH?is regarded as a new type of inorganic nano-flame retardant filler used in polymer materials to improve the flame retardant properties of polymer materials,due to its non-toxic,low-cost and high-efficiency flame retardant properties.However,because of the poor compatibility between MgAl-LDH and polymer matrix,which seriously affects the mechanical properties of PP polymer materials.Intercalation modification of LDH can effectively improve the compatibility of LDH and PP,and enhance the flame retardancy and mechanical properties of PP composites.In this paper,a series of organic and inorganic intercalation modified LDHs were prepared,and used for PP flame retardant.Combined with various characterizations,the microstructure and surface properties of intercalated modified LDH and the flame retardant properties of PP were systematically investigated.The structure-effect relationship between mechanical properties and flame retardant properties is described.The specific research contents are as follows:?1?MgAl-LDH intercalated with Sodium dodecyl sulfate Stearic acid was prepared by calcination recovery method.The results show that the hydrophobicity of the surface of the organic anion intercalated LDH is greatly improved and the particle size becomes smaller.Among them,the Stearic acid intercalated LDH?S-LDH?has a smaller particle size,a narrower particle size distribution,and a stronger surface hydrophobicity.The compatibility of S-LDH with PP matrix material is significantly improved.The LOI of S-LDH/PP composite is 26.3%,UL94 has reached V-1 level,and the PHRR drops to 428.8 kW·m^-2,which fell by 65.6%compared to pure PP.?2?The Stearic acid and molybdate were intercalated in the layer plates of LDH to assemble a series of organic-inorganic intercalated LDH functional materials?SMo-LDH?.The effects of mass ratio of Stearic acid/ammonium molybdate on the morphology and surface properties of SMo-LDH were investigated.The results show that when the mass ratio of Stearic acid/ammonium molybdate is 1:4,3:7 and 1:1,Stearic acid and molybdate are co-inserted into the LDH layer.When the mass ratio of Stearic acid/ammonium molybdate is 1:1,S1Mo1-LDH has both high surface hydrophobicity and molybdate content.The flame retardancy of S1Mo1-LDH on PP was investigated by means of LOI,UL-94 and cone calorimeter?CC?.The LOI of the S₁Mo₁-LDH/PP composite was 27.4%,the UL94 had reached the V-0 level,and the PHRR decreased to 379.8 kW·m^-2,which was 69.3%lower than that of the pure PP.?3?Based on the"memory effect"of LDH,the molybdate intercalated LDH was inserted into the LDH layer by calcination recovery method to prepare MoO_x-loaded LDH,and intercalated with Stearic acid was prepared by calcination recovery method?S-Mo/LDH?.The results show that the interlayer molybdate anion to change into MoO_x particles due to the calcination process.The surface hydrophobicity of S-Mo/LDH is further increased,the contact angle is as high as 145°,and the compatibility with the PP matrix material is further enhanced.The PP/S-Mo/LDH sample has excellent flame retardant properties?LOI:28.6%,UL94:V-0,PHRR is71.6%lower than pure PP?and better mechanical properties.MoO_x-loaded Stearic acid intercalated LDH functional materials have not been reported.