The Preparation Of Bio-based Flame Retardants And The Performance Of Flame Retardant Waterborne Epoxy Resins

In this paper,the bio-based material K-carrageenan was fractionated and degraded to obtain K-carrageenan oligosaccharide(KC),and then phosphated K-carrageenan(PKC)was obtained by reacting POCl3 with KC.P-KC and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide(DOPO)were added into waterborne epoxy(EP)to improve its flame retardancy.The structure of P-KC was studied comprehensively using Fourier transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS),thermo-gravimetric analysis(TGA),showing the successful synthesis of P-KC.The flame retardancy of the EP was evaluated by the cone calorimeter test.The results showed that different mass ratios of DOPO and P-KC affected the flame retardancy of EP.When the mass ratio of DOPO and P-KC was 2:1,total heat release(THR)and total smoke production(TSP)decreased by 49% and 37%,respectively.The microstructures of residue char were observed by FTIR and scanning electron microscopy(SEM),indicating that the flame-retardant waterborne epoxy(FREP)system held a more cohesive and denser char structure.The char inhibited the diffusion of heat and oxygen,which played a key role in the flame retardancy.Therefore,in order to further improve the flame retardant efficiency and smoke suppression performance of KC.In this paper,K-Carrageenan-iron complex(KC-Fe)was synthesized by complexation between KC and Fe Cl3.Furthermore,KC-Fe and ammonium polyphosphate(APP)were added into waterborne epoxy(EP)simultaneously to improve its flame retardancy and smoke suppression performance.The structure and properties of KC-Fe were studied by Fourier transform infrared spectroscopy(FTIR),Ultraviolet(UV)spectroscopy,Thermo-gravimetric analysis(TGA)and X-ray powder diffraction analysis(XRD).The analysis showed that KC-Fe was successfully synthesized and exhibited a good thermal property,and its combustion products can generate catalytic iron oxide.The enhanced flame retardancy and smoke suppression performance of waterborne epoxy were evaluated by limiting oxygen index(LOI)and UL-94.Moreover,the fire retardancy of waterborne epoxy coated on the steel plate was also investigated through cone calorimetry.The results showed that the fire retardant waterborne epoxy exhibited the best flame retardancy when the mass ratio of APP and KC-Fe was 2:1.LOL reached 29.5%,the total heat release(THR)and total smoke production(TSP)decreased by 44% and 45%,respectively,which indicated the good fire safety performance and smoke suppression property.Further analysis of the residual char by FTIR,SEM and elemental analysis(EDS)indicated that the synergistic and catalytic effect of KC-Fe with APP.The formation of dense thermal stable char layer from intumescent coating is essential to protect the underlying materials in this work.