Innovative multifunctional fire retardance of poly(butylene adipate-co-butylene terephthalate)-based bio-composite formulation

PBAT/3wt C-CS not only shows self-extinguishing, anti-dripping effect, and excellent flame retardant performance, but also demonstrates anti-bacterial, anti-UV properties, and increased crystallizability and hydrophilicity. [Display omitted] •Synthesized fully bio-derived chitosan-based particles (C-CS) enhanced self-extinguishing and anti-dripping effect of PBAT.•Composite (PC3) achieved the highest V-0 fire safety rating and showed excellent flame retardant performance.•Significantly enhanced amount of char residue played a decisive role on enhancement of fire-proofing.•PC3 demonstrated anti-bacterial, lowered UV-transmittance properties and increased crystallizability. Poly(butylene adipate-co-butylene terephthalate) (PBAT), a biodegradable aromatic-aliphatic copolyester, has been widely applied in various fields, but it shows the flammability, resulting in serious fire risk. The flame retardancy of some PBAT/polymer blend systems have been studied, but that of neat PBAT was seldom reported. In particular, the research and development of the bio-based green flame retardant agent is highly desired. In this work, fully bio-derived modified chitosan particles (C-CS), were synthesized and used to prepare a novel PBAT-based multifunctional flame-retardant composite. The PBAT/3%C-CS composite (PC3) exhibited an excellent anti-dripping and self-extinguishing performance and achieved the highest fire safety rating (V-0). Peak of heat release rate and total heat release reduced by 39.8 % and 14.9 %, respectively. The char residue yield of the PC3 increased by 211.6 % in the PC3, compared with that of neat PBAT. Both condensed- and gas-phase played dual roles on increasing the flame-retardant performance of the PC3. The PC3 showed a relatively compact and continuous char layer which acted as a physical barrier to suppress the heat exchange and O2 entry (into the matrix) in the combustion process. Meanwhile, the concentration of O2 and H·/HO· free radicals were diluted by a small portion of non-flammable gas products in the pyrolysis process. Also, the PC3 presented elevated crystallizability and anti-bacterial effect, and reduced UV-transmittance characteristic.