Study on curing and flammability properties of UV-curable flame-retardant coating on jute/polypropylene composites surface

A UV-curing flame-retardant coating with varying mass content of bisphenol A epoxy acrylate (BAEA), 2-hydroxyethyl methacrylic acid phosphate (PM-2) and polyurethane acrylate (PUA) were prepared, improving the flame-retardant and mechanical properties of jute/polypropylene (PP) composites. BAEA is the main film-forming prepolymer. Phosphate ester groups in PM-2 can promote the formation of carbon layer during combustion, and PM-2 can also be used as a good adhesion binder to improve the coating adhesion levels. The flexible long chain in PUA could reduce the shrinkage of the coating and provide further adhesion. To avoid the oxygen inhibition of the radical polymerization, isopropylthioxanthone and triethanolamine were used to reduce the reaction between photoinitiator phenyl bis (2,4,6-trimethylbenzoyl) phosphine oxide and oxygen. Compared to the uncoated composites (J–P), the peaks of heat release rate and total smoke production of coated composites decreased and limiting oxygen index values increased significantly, which revealed that the coatings showed effective fire protection effect. The bending strength of the coated composites can increase by 90% over uncoated sample J–P. This simple, low-cost and environmentally friendly UV-curing coating has good adhesion and can effectively improve the flame-retardant and mechanical properties of composites, which expand application of the flame-retardant fiber composites.