Influence of Core-Shell Structure and Cladding Sequence of Microencapsulated Ammonium Polyphosphate on the Flame-Resistant and Smoke Inhibition Efficiency for PBAT Composites

To demonstrate the influence of core-shell structure of microencapsulated ammonium polyphosphate (MCAPPs) on the flame-resistant and smoke inhibition efficiency of polymer composites, four kinds of MCAPPs with unilaminar or bistratal shells were fabricated and used to fabricate flame retarded Poly (butyleneadipate-co-terephthalate) (PBAT) composites. The MCAPP with cross-linked β-cyclodextrin as outer layer (MFAPP-CD 1 ) exhibited the highest flame-resistant efficiency. Accordingly, 75P/25MFAPP-CD 1 showed the highest char residue and densest char layer, also the lowest pHRR and THR, decreasing by 77.4 and 76.9% compared with PBAT, respectively. Meanwhile, the lowest SPR and TSP also demonstrated its excellent smoke inhibition effect due to the weakened catalytic effect of Ammonium polyphosphate (APP) on carbonization agent. As a result, a LOI value (33.2%) and UL-94 V0 rating could be achieved. A reasonable core-shell structure could improve the carbon forming capacity and reduce the release of volatiles during combustion. Polyhydroxy carbonization agent should be designed as the outer layer of bistratal MCAPP. Graphical Abstract