Enhancing the comprehensive performance of bisphenol A epoxy resin via blending with a bio-based counterpart

Modification of epoxy resins has emerged as a growing trend but also presents significant challenges, as it is difficult to trade off various properties, for example, improving the toughness of the resin often sacrifices its thermal stability and flame retardancy. In this study, a bio-based tetra-functional epoxy precursor (MTEP) derived from magnolol was blended to comprehensively improve the performances of the commonly used petroleum-based bisphenol A epoxy precursor (E51) with 4,4′-diaminodiphenyl sulfone (DDS) as curing agent, and the thermal stability, mechanical properties and flame retardancy of the blended systems were evaluated. The results showed that the MTEP/E51/DDS blend resin exhibited maximum impact strength (37.8 MPa), representing a 54.3% improvement over E51/DDS (24.5 MPa). The addition of 50 wt% of MTEP into E51/DDS increased the flexural modulus up to 3281 MPa (by ∼23.6%), in combination with appreciable increases in the glass transition temperature (by 50 °C) and intrinsically flame retardancy in UL-94 test (from NR to V-0). The above results prove that it is feasible to improve the performances of petroleum-based epoxy resin with high-performance bio-based counterpart, which is often the opposite before, which also provides a novel approach for the modification of epoxy resin.