Ultra-high flame-retardant efficiency of phosphorous-silicon hybrid microsphere in poly (butylene adipate-co-terephthalate)

A phosphorous-silicon (SiP) precursor was synthesized using p-phthalaldehyde, (3-aminopropyl) triethoxysilane and 9,10-dihydro-9-oxa-10-phosphaphenantrene-10-oxide. The SiP was used to fabricate a phosphorous-silicon hybrid microsphere (SiP-M) via the sol-gel method. The SiP-M was employed to enhance the flame retardancy of poly (butylene adipate-co-terephthalate) (PBAT). The results indicate that PBAT containing 0.1 wt% of SiP-M displays a UL-94 V0 rating and a limiting oxygen index (LOI) value of 26.5 vol%. Meanwhile, PBAT containing 1.0 wt% SiP-M exhibits a UL-94 V0 rating and a LOI value of 29.8 vol%, and some reductions in peak heat release rate, total heat release, and total smoke production. The SiP-M functions in both the gas phase and condense phase in the PBAT blend, and the former is predominant. In addition, a coupling agent KH560 was used to modify the interface adhesion between PBAT and SiP-M. The tensile strength and elongation at the break of PBAT blends are enhanced by an appropriate amount of KH560. This work provides an efficient method for preparing flame-retardant PBAT without deteriorating its mechanical properties.