Synthesis Of Piperazine Based Phosphate And Its Application In Flame Retardant Polypropylene

The research of novel phosphorus-nitrogen flame retardants is important to the developmentof halogen-free flame retardant. In this study, piperazine phosphate and pyro/polyphosphatepiperazine (the mixture of pyrophosphate piperazine and polyphosphate piperazine) weresynthesized. And the results of fourier transform infrared spectroscopy (FTIR), elemental analysis(EA), X-ray diffraction (XRD) and31P solid NMR indicated that these two target products own theexpected chemical composition and molecule structure. EA results showed that phosphoruscontent of piperazine phosphate is14.06%, while pyro/polyphosphate is24.88%.Thermogravimetric analysis(TGA) was employed to determine the thermal stability of these twoproducts, pyro/polyphosphate piperazine showed high thermal stability and good char formingability which can be used to flame retarded polypropylene?PP?.Two different flame retardant PP blends (FR-PP) system were prepared, one was only addedpyro/polyphosphate piperazine as flame retardant, another one was compounded system that is themixture of pyro/polyphosphate piperazine, Melamine-ammonium polyphosphate(MEL-APP) andpentaerythritol phosphate(PEPA).Flammability properties and mechanical properties of FR-PP were characterized by Limitoxygen index(LOI), vertical burning(UL-94), tensile test and impact test. For the single-component (only added pyro/polyphosphate piperazine) added system, the results showed that,flame retardant performance of FR-PP became better with the flame retardant dosage increased.FR-PP filled with25wt%and30wt%pyro/polyphosphate piperazine achieved the LOI value of29.3%and30%,and UL-94V-2(3.2mm) grade respectively. When the FR-PP filled with pyro/polyphosphate piperazine: MEL-APP: PEPA=5wt%:20wt%:5wt%, FR-PP achieved the LOIvalue of38.4%, and UL-94V-0(3.2mm) grade. The compounded system gave the FR-PP betterflame retardancy. While the comprehensive mechanical properties of the compounded systemneed more further researches to find suitable ways to improve.The flame retardant mechanism of single-component added FR-PP and synergistic FR-PPwere investigated by TGA, Py-GC-MS analysis, Raman, EA, XRD and SEM. TGA results showedthat pyro/polyphosphate piperazine made FR-PP higher maximum thermal decompositiontemperature and done good to char forming during the decomposition process. The synergistswere especially conducive to FR-PP's char forming in air atmosphere. The results of Py-GC-MSanalysis and other tests of residues showed that the mechanism of single-component added FR-PPand synergistic FR-PP are mainly condensed phase mechanism.