Line Cyclotriphosphazene Ring Structure-Bisphenol A Type Epoxy Resin Synthesis、 Characterization And Flame Retardancy

Epoxy resin with good chemical stability, good dielectric properties andhigh strength performance, a lot of applications in various fields. However,due to its flame-retardant performance is not good, it is flammable, so flameretardant modification of the epoxy resin is particularly important. Cyclolinearcyclotriphosphazene structure introduced into the epoxy matrix can beprepared with halogen-free flame-retardant epoxy resin. The main work is asfollows:1. Synthesis and preparation of the self-flame retardant epoxy resin withcyclolinear cyclotriphosphazeneA novel halogen-free flame-retardant epoxy resin was designed in termsof a cyclolinear cyclotriphosphazene-linked mode and was synthesizedthrough a three-step synthetic route. The chemical structures and compositionsof all the cyclotriphosphazene precursors and the final objective product wereconfirmed by¹H and³¹P NMR spectroscopy, elemental analysis, and Fourier transform infrared spectroscopy. The thermal curing behaviors of thesynthesized epoxy resin with dicyandiamide,4,4’-diaminodiphenylmethane,and novolak as hardeners were investigated by differential scanningcalorimetry （DSC）, and their heat resistance and thermal stabilities were alsoevaluated by DSC and thermogravimetric analysis. These thermosets achieveda high thermal resistance due to their high glass transition temperaturesbeyond150°C and simultaneously gained a good thermal stability with highchar yields. The flammability characteristics of the thermosets obtained by thisepoxy cured with three hardeners were studied on the basis of the resultsobtained from the limiting oxygen index （LOI） and UL–94vertical burningexperiments as well as the analysis of residual chars collected from UL–94test. The high LOI values and UL–94V–0classification of these epoxythermosets indicate that the incorporation of phosphazene rings into themolecular backbone imparts nonflammability to the epoxy resin as a result ofthe unique combination of phosphorus and nitrogen following by a synergisticeffect on flame retardancy. The epoxy resin synthesized in this study is a greenfunctional polymer and will become a potential candidate for fire-andheat-resistant applications in electronic and microelectronic fields with moresafety and excellent performance.3. Synthesis and preparation of the cyclolinear cyclotriphosphazene-linkedepoxy resin modified flame retardancy of bisphenol A epoxy resin To modify the flame retardant properties of bisphenol A epoxy resin, wesynthesized a cyclolinear cyclotriphosphazene-linked epoxy resin （TGZAF）.he chemical structures and compositions of all the cyclotriphosphazeneprecursors and the final objective product were confirmed by¹H and³¹PNMR spectroscopy, and Fourier transform infrared spectroscopy. UltimatelyE51with20wt.%TGZAF, MeTHPA curing, get a UL-94V-0flammabilityrating of cured epoxy resin. The heat resistance, elastic modulus and fracturestrength of E51with20wt.%TGZAF relative to the original cured epoxyresin have been improved, but its thermal stability reduces.