Effect of diluent on the properties of intrinsically flame-retardant vinyl ester resins and their fiberglass-reinforced composites

To overcome the flammability and severe smoke release of vinyl ester resin and to explore the effect of a diluent on its properties and those of fiberglass-reinforced composites, a bio-based vinyl ester resin monomer was prepared from magnolol and glycidyl methacrylate. Its structure was confirmed by Fourier-transform infrared spectroscopy and ¹H and ¹³C nuclear magnetic resonance spectrometry. The monomer was dissolved in styrene and methacrylic acid to obtain bio-based resins designated as SDAR and MADAR, respectively, and their fiberglass-reinforced composites GFSDAR and GFMADAR were prepared. Dynamic mechanical analysis showed that MADAR (142.8 °C) and its composite (146.2 °C) have higher glass transition temperatures than SDAR (112.1 °C) and its composite (122.3 °C). Bending tests on GFMADAR showed that its flexural strength (378.9 MPa) and flexural modulus (19.95 GPa) is higher than those of GFSDAR (247.7 MPa and 16.27 GPa, respectively) due to better wettability of fiberglass. Cone calorimeter results indicated that the total heat release and total smoke production of GFMADAR are reduced by 19.5% and 31.9% compared with those of GFSDAR. The good wettability of MADAR on fiberglass and strong contact between its char residue and fiberglass endow GFMADAR with superior flame retardancy and smoke suppression. This work demonstrates a new method for preparing high-performance vinyl ester resin and its fiberglass-reinforced composite.