Engineering

Char

Epoxy

Materials science

Fire safety

Ultimate tensile strength

Biochemistry

Civil engineering

Chemical engineering

Cone calorimeter

Organic chemistry

Combustion

Flammability

Resveratrol

Composite material

Chemistry

Fire retardant

Thermal stability

Toughness

Chemical Engineering Journal

The integration of flame-retardant additive with both excellent thermal stability and remarkable fire-retarded efficiency into epoxy resins (EP) is highly demanded while challenging. Herein, a novel bio-based flame retardant (referred to DPOR) was synthesized via one-step reaction of resveratrol and diphenylphosphonyl chloride. The as-prepared DPOR exhibited outstanding thermal stability, with an initial thermal decomposition temperature of 438.4 °C, contributing from the reduced intermolecular π–π interaction and incremental oligomerization during the heating process. It was further utilized as additive for the manufacture of high-performance EP composites (EP-DPOR). Notably, DPOR can also act as mechanical reinforcer that enhanced the strength and toughness of EP. The EP-DPOR3 (3 wt% DPOR) showed a superior stretchability (15.9 %) and high tensile strength (59.3 MPa) compared to neat EP (12.4 %, 46.7 MPa). Additionally, the burning test results indicated that DPOR endowed the EP with greatly enhanced flame resistance, achieving a UL-94 V-0 rating with an increase of LOI values to 34.5 % at a low loading of 5 wt%. In cone calorimeter tests, it showed that heat and smoke release was effectively inhibited during combustion in comparison with EP, wherein the PHRR value of EP-DPOR was 27.5 % lower than EP. Thus, it is highly anticipated that DPOR, as a new type of bio-based flame retardant with superior thermal stability and efficient flame- retardant properties, holds a great potential for the development of next-generation flame retardant.

Highly thermo-stable resveratrol-based flame retardant for enhancing mechanical and fire safety properties of epoxy resins