Engineering carbon nanotubes wrapped ammonium polyphosphate for enhancing mechanical and flame retardant properties of poly(butylene succinate)

The performance of CNTs with different amounts and dispersion states were explored in the flame retardant system as PBS/APP. Herein, A series of CNTs wrapped ammonium polyphosphate (named CAPP) were successfully prepared and characterized, and then blended into Poly(butylene succinate) (PBS) as an additive-type flame retardant. The obtained PBS/CAPP contributes to forming much more graphitized char layers to reduce the heat transfer and toxic gases release. For instance, PBS-3 containing 20% CAPP1 wrapped by only 1% of CNTs shows the best anti-dripping effect and the lowest toxic gases release, where CO₂ and CO yield dramatically reduced by about 68.3% and 72.6%. With the same content of CNTs, the tensile strength, elongation at break and unnotched impact strength of PBS-3 increased about 10.8%, 14.2% and 5.3% than PBS-5 (CNTs added directly). Thus, the well dispersion state of moderate CNTs has a positive impact on improving mechanical properties, flame retardancy and smoke suppression.