Magnolol-based bio-epoxy resin with acceptable glass transition temperature, processability and flame retardancy

[Display omitted] •A bio-based intrinsic flame retardancy epoxy resin was prepared from magnolol.•It showed high thermal stability with Tg > 250 °C and Td5% > 400 °C.•The system exhibited outstanding processability, very suitable for RTM process.•The system presented ‘Excellent’ and ‘Good’ in Cure and Flame Retardancy Index.•It also exhibited higher mechanical modulus and strength than DGEBA. Development of sustainable bio-based epoxy resins having better comprehensive properties than available petroleum-based epoxy resins is of paramount importance for alleviation of energy pressure and enrichment of the potent category of high-performance epoxy resins. In this study, a fully bio-based epoxy resin precursor (DGEM) was synthesized from a naturally occurring magnolol through a highly efficient one step process. The bio-based epoxy resin obtained was then cured with 4, 4′-diaminodiphenyl sulfone (DDS) and compared to the petroleum-based commercial diglycidylether of bisphenol A (DGEBA). After curing with DDS, DGEM/DDS showed higher glass transition temperature than DGEBA/DDS which was 279 °C and 231 °C, respectively. The char yield (in N2), storage modulus and flexural modulus of the former were 1.9-fold, 47.5%, and 41.3% higher than those of the latter, respectively. Interestingly, bio-based epoxy resin of DGEM exhibited excellent processability with extremely low viscosity of 0.155 Pa·s at room temperature and a broader processing window than DGEBA/DDS as well. To exhibit such an excellent processability is very rare for high-performance epoxy resins. In addition, the cured DGEM/DDS also showed outstanding intrinsic flame retardancy, which passed the V-0 rate of UL-94 test. This study offers an opportunity to prepare bio-based epoxy resins with better properties than DGEBA and exhibits great promise in cutting-edge applications.