| Epoxy resins are widely used in coatings,adhesives,composite materials,and electronic materials because of their high mechanical strength,excellent electrical insulation,strong chemical stability,and excellent bonding properties.However,the most widely used bisphenol A epoxy resin in the market is flammable materials,and the limiting oxygen index is only 19.8wt%,which greatly limits its application in some special fields.Phosphorus-based flame retardant structure DOPO has become a hot topic at home and abroad due to its not release harmful gases,high reactivity,and high flame retardant efficiency.At present,DOPO-added epoxy resins have problems such as poor dispersibility and poor compatibility of the flame retardant with the resin matrix;DOPO-type epoxy resin curing agents have problems such as fewer reactive sites and incomplete curing;and DOPO-type inherent flame retardants Epoxy resin can avoid the problems of the above two forms,but it is much more difficult than the above two forms in the design of the molecular structure and the synthesis of the epoxy resin.Therefore,there are few reports on the synthesis of essential flame retardant epoxy resins using DOPO.So design and synthesize a kind of DOPO basic flame-retardant epoxy resin is a challengeIn addition,the main raw material of commercial bisphenol A epoxy resin,bisphenol A,is considered to be an interference of human reproductive toxins and endocrine systems,which seriously endangers human health and safety.In addition,bisphenol A comes entirely from fossil resources.With the world's energy depletion becoming more and more serious,environmental protection has become increasingly important.The epoxy resin industry urgently needs a kind of bio-derived raw materials to synthesize epoxy resin.From the perspective of molecular design,a bio-based platform compound—bisphenolic acid and DOPO were used as the main raw materials and a three-step method was used to synthesize the essential flame-retardant bio-based epoxy resin TEBA based on DOPO phosphorus-nitrogen synergy.Then,the structural characterization of TEBA and intermediate products were performed to characterize the molecular weight,epoxy equivalent and phosphorus content of TEBA;the optimal curing conditions of TEBA-DDM system were determined;in addition,the curing kinetics of TEBA-DDM was also studied.The results show that the epoxy equivalent of TEBA is 273-289 g / eq,the phosphorus content is 2.32 wt%,and the average apparent activation energy Ea is 52.35 kJ.The TEBA-DDM was compared with the commercial epoxy resin DGEBA-DDM,and TEBA and DGEBA were blended in different proportions to prepare a mixed system resin cross-linked cured product.Study the thermomechanical and thermal stability,flame retardancy,and flame retardance mechanism of TEBA-DDM.Study the thermal stability,flame retardancy and mechanical properties of TEBA blended polymers,and explore the feasibility of TEBA replacing or partially replacing DGEBA.The results show that the TEBA-DDM LOI is 42.3%,and the UL-94 test reaches V-0.Compared with DGEBA-DDM,the peak heat release rate(PHRR)is reduced by 67%.Total heat release(THR)and total smoke production(TSP)were reduced by 27% and 35%,respectively.When the TEBA blending ratio is 0.25,the blending system has high thermal stability,excellent flame retardancy and excellent mechanical properties.The feasibility of TEBA replacing or partially replacing DGEBA has been proved. |
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