State-of-the-Art Research in Flame-Retardant Unsaturated Polyester Resins: Progress, Challenges and Prospects.

Unsaturated polyester resins (UPR) are broadly applied in chemical, construction, transportation and electrical fields, etc. However, UPR materials are extremely flammable. Through radiation, conduction and convection, the released heat brings serious thermal hazards to surrounding life and the environment. Meanwhile, the combustion of UPR also releases a vast of toxic pyrolysis gases and smoke, causing extremely serious non-thermal hazards, endangering life and health, reducing fire visibility and hindering escape and rescue efforts. Therefore, the flame retardant modification of UPR materials is an inevitable measure to reduce its flammability and broaden its application breadth. In this review, the flammability of UPR materials is firstly analyzed from the perspective of their compositions and structures. Meanwhile, based on the differences in preparation methods of flame retardant UPR (FR-UPR) in literature research, it is divided into additive flame retardant, intrinsic flame retardant and interfacial flame retardant methods. The relationship between the highly efficient flame retardant structures and the properties, and the gaseous-phase flame retardant and condensed-phase mechanisms in FR-UPR composites are analyzed. Compared with traditional additive flame retardants, polymeric flame retardants, nanosheet flame retardants and intrinsic flame retardant method are important directions for the future development of FR-UPR composites. In addition, the interfacial flame retardant method can effectively improve the interfacial adhesion and flame retardant properties of fiber-reinforced UPR composites, and also has application prospects. This review analyzes the current challenges faced by FR-UPR, and looks forward to its possible future development directions to guide the preparation and application of high-performance FR-UPR. [ABSTRACT FROM AUTHOR]