Preparation Of Phosphonium-intercalated Layered Inorganic And The Flame Retardancy Application In Polypropylene

Compared with traditional flame retardants, polymer/inorganic particlesnanocomposites represent a new technology of flame retardant field, and adding smallamount of inorganic particles can significantly improve the mechanical properties,thermal properties and barrier properties of composite materials. The research in thisfield are mostly concentrated on layered inorganic particles organically modified bylong-chain alkyl quaternary ammonium salt, but the decomposition temperature ofquaternary ammonium salt is mostly below200°C, so the thermal stability and flameretardant property are poor. We prepared vermiculite intercalated by quaternaryphosphonium salt and zirconium phosphate intercalated by quaternary phosphoniumsalt, their thermal stability is better. Use these two layered inorganic particles,intumescent flame retardant and polypropylene to prepare nanocomposites viamelting blending, then characterize the structure and properties of materials.Firstly, intercalate vermiculite （VMT） with dodecyl tributyl phosphoniumchloride (P₁₂) and generate P₁₂-VMT, then combine P₁₂-VMT and intumescent flameretardant （IFR） to prepare PP/IFR/P₁₂-VMT nanocomposites. Characterize thecomposites by scanning electron microscopy, found that the addition of P₁₂-VMT canimprove the compatibility between intumescent flame retardant and PP matrix;mechanical properties results show that a small amount of P₁₂-VMT can improve themechanical properties of composite materials; TGA, LOI and UL-94test prove thatP₁₂-VMT and IFR have good synergy effect: adding2wt%P₁₂-VMT while thecontent of IFR is26wt%, UL-94test reach V-0grade and LOI is the highest32.7;adding28wt%IFR without P₁₂-VMT, UL-94test is V-1grade and LOI is30.0.Then, we synthesize layered α-zirconium phosphate（α-ZrP）, intercalate it withcetyl tributyl phosphonium bromide (P₁₆) and generate P₁₆-ZrP, and combine P₁₆-ZrPand intumescent flame retardant（IFR） to prepare PP/IFR/P₁₆-ZrP nanocomposites.Characterize the composites by scanning electron microscopy, found that the additionof P₁₆-ZrP can improve the compatibility between IFR and PP matrix; mechanical properties results show that a small amount of P₁₆-ZrP can improve the mechanicalproperties of composite materials; TGA, LOI and UL-94test prove that P₁₆-ZrP andIFR have good synergy effect: adding2wt%P₁₆-ZrP while the content of IFR is26wt%, UL-94test reach V-0grade and LOI is the highest33.0; adding28wt%IFRwithout P₁₆-ZrP, UL-94test is V-1grade and LOI is30.0.