Preparation And Mechanism Of Bio-based Flame Retardant Based On Amino Acid

The application of polymer materials is more and more extensive,but their flammability seriously threatens the safety of people's lives and property.Therefore,it is especially important to improve the flame retardancy of polymer materials.In recent years,with the improvement of people's awareness of environmental protection,the concept of green,environmentally friendly and sustainable development has become the development and application of flame retardants.Therefore,flame retardants prepared by using bio-based materials have attracted more and more attentions.In this paper,bio-based flame retardants were prepared by using amino acids such as glycine?Gly?,phenylalanine?PHE?and lysine?Lys?as raw materials,and applied to intumescent flame retardants?IFR?.The flame retardancy and flame retardant mechanism were studied.The details are as follows:?1?N,N',N”-1,3,5-triazine-2,4,6-triyltris-phenylalanine?TTP?and N,N',N”-1,3,5-triazine-2,4,6-triyltris-glycine?TTG?were synthesized by Gly,PHE and cyanuric chloride?CC?.The structure and performance were characterized by ¹H NMR,Fourier transform infrared spectroscopy?FTIR?and thermogravimetric analysis?TGA?.TTG and TTP were used into polypropylene?PP?/IFR systems and their flame retardancy was analyzed.The limit oxygen index?LOI?and UL-94 vertical burning test showed that 1 wt%TTP or TTG can significantly improve the LOI values of PP/IFR composites,and TTG shows better flame retardant efficiency.The results of TGA and scanning electron microscopy?SEM?showed that TTG can promote the formation of high quality expanded char layer in PP composites,whereas that of TTP is poor.?2?In order to study the synergy of TTG in the PP/IFR system,PP composites with different formulation ratios were prepared,and their flame retardancy and flame retardant mechanism were analyzed.The flame retardant properties of PP composites were evaluated by LOI and UL-94vertical burning test.The results showed that 17 wt%IFR and 1 wt%TTG makes PP achieve UL-94 V0 rating without drippings,and the LOI value is increased to 29.5 Vol%.The thermal degradation behavior and char morphology of PP composites were investigated by TGA and SEM.The results indicated that TTG accelerates the formation of char layer,regulates the porous structure of char layer,and enhances its barrier property.According to the results of infrared thermal imaging test,temperatures of PP composites after two ignitions during the UL-94 test are decreased significantly,indicating that TTG promotes the rapid formation of the char layer.In addition,the combustion behaviors of PP composites were investigated by cone calorimeter.The PHRR of PP composites is 67%reduced,and the t_PHRR is delayed from 223 s to 430 s,indicating the reduction of combustion risk for PP composites.Through the mechanical properties test,it shows that TTG can improve the elongation at break and impact strength of PP/IFR composites.?3?CC-Lys was prepared by Lys and CC,and its structure and performance were tested by FTIR and TGA.Mixed with ammonium polyphosphate?APP?and Organic montmorillonite?OMMT?,CC-Lys was used into Ethylene-vinyl acetate?EVA?,and the flame retardancy and mechanism were analyzed.The results of LOI and UL-94 test showed that APP and CC-Lys have better flame retardancy at a ratio of 3:1.After addition of 1 wt%OMMT,25 wt%loading of flame retardants increased the LOI to 33.1 Vol%,and 20 wt%loading can make EVA pass UL-94 V0rating.The results of TGA,TG-IR,SEM and FTIR tests showed that there is a strong interaction between the flame retardants,which effectively reduces the release of combustible gases and promotes the formation of a porous expanded carbon layer during the degradation of EVA composites.Meanwhile,the fused ring structure in the char is increased,and the quality of the char layer is improved.