Synthesis Of Novel Intumescent Flame Retardant And Properties Investigation Of Flame Retardant Polypropylene

In the thesis,a novel hyperbranched and phosphorus-containing triazine char forming agent(CFA)was synthesized.The relationship between the structure and properties of triazine CFA was studied.On that basis,a mono-component IFR was synthesized and applied to PP.Furthermore,SiO2 and OMMT were used to improve the flame retardancy efficiency and comprehensive performance of the one-component IFR.The specific contents are as follows:1.Phosphorus-containing triazine CFA,named HPCFA,was synthesized by cyanuric chloride,piperazine and phenyl phosphoryl chloride.The chemical structure of HPCFA was characterized by FTIR and elemental analysis.TGA showed that HPCFA was thermal stable with Tonset as high as 320 ? under N2 atmosphere.The char residue of HPCFA at 700 ? was 45.3%.HPCFA/APP was used as IFR to PP.It showed the highest flame retardant efficiency when the mass ratio of HPCFA/APP was 1/2.PP/IFR composite could achieve LOI value of 31%and UL 94 V-0(3.2mm)rating at 20 wt%HPCFA/APP(1/2,w/w)loading.2.A comprehensive comparison was made between HPCFA and HCFA,which had similar triazine structures.TGA showed that the Tonset of HPCFA was lower,owing to the catalytic effect of phosphorus units in its molecular.The phosphorus units in the HPCFA molecular structure played a complementary role in the acid source,and the catalytic effect of the intramolecular acid source is highly efficient,which led to a higher flame retardant efficiency.The results of vertical burning test showed that the PP/IFR composite could reach UL 94 V-0(3.2mm)rating with only 20 wt%APP/HPCFA loading,while it was 25 wt%for APP/HCFA.3.A novel mono-component intumescent flame retardant,named as hyper-branched triazine-piperazine pyrophosphate(HTPPP),was synthesized by using cyanuric chloride,1-boc-piperazine and phosphoric acid.Chemical structures of HTPPP are characterized by FTIR spectra,31P NMR,solid-state 13C NMR,EA and ICP-MS.The resulting HTPPP was used alone as IFR for PP.PP/HTPPP composite could achieve LOIvalue of 30.5%and UL 94 V-0 rating at 25 wt%HTPPP loading.Besides,HTPPP was thermally stable with Tonset as high as 275 ? in air atmosphere.The flame retardancy mechanism was concluded based on the analysis of the char residue.4.The synergistic effect and mechanism of SiO2 with different morphologic and surface properties on PP/HTPPP system were studied.The flame retardancy test(vertical burning,LOI)indicated that SiO2 could improve the flame retardancy effectively,especially for hydrophobic fumed silica(FS).With addition of 0.5 wt%hydrophobic FS,the PP/HTPPP 20 composite could achieve UL 94 V-0(3.2mm)rating and LOI value of 31.5%.TGA revealed that SiO2 could increase the pyrolysis temperature and reduce the pyrolysis rate of PP.Furthermore,thermal stability of the char residue at high temperature was improved greatly.The structure analysis of the char residue showed that SiO2 could promote the formation of Si-C.5.Swelling OMMT and monomers of HTPPP were mixed,and then HTPPP-OMMT complex was prepared by dehydrating.The results of FTIR and NMR showed that there was no change in the chemical structure of HTPPP.XRD showed that the layered structure of OMMT was highly dispersed in HTPPP.The intercalation of OMMT increased the condensation degree of HTPPP,thus reducing the water solubility and increasing the thermal stability.HTPPP-OMMT was used as a mono-component IFR to PP.It was found that HTPPP-OMMT showed higher flame retardant efficiency based on forming more compact and higher thermal stability carbon layer compared with HTPPP.Moreover,there was a good compatibility between HTPPP-OMMT and PP,the mechanical properties and precipitation resistance of PP/HTPPP-OMMT composite were improved.