Synthesizeof Novel Cyclotriphosphazene-based Flame Retardants And Theirs Application In Polypropylene

The novel flame retardants hexa (m-phenylenediamine) cyclotriphosphazene (HmPDACP)、hexadiphenylcarbazide cyclotriphosphazene (HDPCCP) and hexa (n-phenylurea) cyclotriphosphazene (HNPUCP) were synthesized by using hexachlorocyclotriphosphazene、m-phenylenediamine、diphenylcarbazide and n-phenylurea as raw materials, the factors affecting the yield of target product were investigated; the structure of HmPDACP、HDPCCP and HNPUCP were analyzed by FT-IR and NMR and theirs thermal properties were studied by TGA; the flame retardant and mechanical properties of polypropylene material treated with HmPDACP、HDPCCP and HNPUCP respectively were tested; the mechanism of the flame retardant was discussed through analyzing the scanningelectronmicroscopy (SEM) pictures of burning residue from treated polypropylene.The factors affecting the yield of target product were investigated and the optimized condition of HmPDACP were:m-phenylenediamine was fed in drops and reaction temperature (T), reaction time (t) and molar ratio were:T=25℃, t=6h, n (hexachlorocyclo phosphazene)/(m-phenylenediamine)=1/6.17, the yield of HmPDACP was72.68%; the optimized condition of HDPCCP were:T=60℃, t=12h, n (hexachlorocyclo phosphazene)/(diphenylcarbazide)=1/6.06, the yield of HDPCCP was43.54%; the optimized condition of HNPUCP were:T=50℃, t=12h, n (hexachlorocyclo phosphazene)/(n-phenylurea)=1/6.10, the yield of HNPUCP was31.76%.The structure of HmPDACP、HDPCCP and HNPUCP were analyzed by FT-IR and NMR and it basically met the expected goal.TGA was used to study the thermal properties of HmPDACP, HDPCCP and HNPUCP and the results were:HmPDACP:decomposition temperature:200℃, the content of residues:42%; HDPCCP:decomposition temperature: 190℃, the content of residues:39%: HNPUCP:decomposition temperature:210℃, the content of residues:25%.Limit oxygen index (LOI) and vertical flame test were used to study the flame retardant of polypropylene material treated with HmPDACP、HDPCCP and HNPUCP respectively (30%) and the LOI were:25.3%、24.1%and23.7%, flammability rating:UL94V-1, and the higher the content of nitrogen and phosphorus, the better the performance of flame retardant:HmPDACP was selected as the object to study how it affected the flame retardant and mechanical properties of polypropylene material and the results were:the tensile strength of polypropylene material decreased slightly with the increase of HmPDACP content and its flexural strength rose at first and went down latter with the change of HmPDACP, while impact strength increased a bit but change slightly when added more HmPDACP.Thescanningelectronmicroscopy (SEM) pictures ofburning residue from treated polypropylene was analyzed and results showed that the addition of flame retardants improved flame retardancy and the sample could form a loose and porous foam carbon layer after burning and the higher the content of phosphorus, the denser and more continuous the carbon layer is.