A bio-based epoxy resin derived from p-hydroxycinnamic acid with high mechanical properties and flame retardancy

摘要

Recent advances in epoxy resins have been forward to achieving high mechanical performance,thermal stability,and flame retardancy.However,seeking sustainable bio-based epoxy precursors and avoiding introduction of additional flame-retardant agents are still of increasing demand.Here we report the synthesis of p-hydroxycinnamic acid-derived epoxy monomer(HCA-EP)via a simple one-step reaction,and the HCA-EP can be cured with 4,4′-diaminodiphenylmethane(DDM)to prepare epoxy resins.Compared with the typical petroleum-based epoxy resin,bisphenol A epoxy resin,the HCA-EP-DDM shows a relatively high glass transition temperature(192.9℃)and impressive mechanical properties(tensile strength of 98.3 MPa and flexural strength of 158.9 MPa).Furthermore,the HCA-EP-DDM passes the V-1 flammability rating in UL-94 test and presents the limiting oxygen index of 32.6%.Notably,its char yield is as high as 31.6%under N_(2),and the peak heat rate release is 60%lower than that of bisphenol A epoxy resin.Such findings provide a simple way of using p-hydroxycinnamic acid instead of bisphenol A to construct high-performance bio-based thermosets.