Modified β-cyclodextrin microspheres towards the application in intumescent fire resistance and smoke-suppressing of bio-based poly(L-lactic acid).

In this work, the β-cyclodextrin (β-CD) was modified by a phosphazene compound to prepare a novel amorphous derivate (β-CDCP), which was combined with the ammonium polyphosphate (APP) as a synergistic flame retardant (FR) of the bio-based poly(L-lactic acid) (PLA). The effects of the APP/β-CDCP on the thermal stability, combustion behavior, pyrolysis process, fire resistance performance and crystallizability of the PLA were investigated comprehensively and in depth by thermogravimetric (TG) analysis, limited oxygen index (LOI) analysis, UL-94 test, cone calorimetry measurement, TG-infrared (TG-IR), scanning electron microscopy-energy dispersive spectrometer, Raman spectroscopy, pyrolysis-gas chromatography/mass spectrometry and differential scanning calorimetry. The PLA/5%APP/10%β-CDCP showed a highest LOI of 33.