A green COPD flame retardant for improving poly(l-lactic acid)

A green flame retardant COPD is synthesized by using chitosan oligosacc- haride (COS), p-hydroxybenzaldehyde and 9,10-dihydro-9-oxa-10-phospho-10-oxide (DOPO) as raw materials according to two-step reaction. The synthesized product is confirmed with FTIR, UV and NMR. When the COPD is inserted into poly(l-lactic acid) (PLLA) via solution blending, the flame retardation of PLLA is improved. As the blend ratio of COPD/PLLA is 20/80, the limit oxygen index (LOI) and UL-94 vertical burning grade 25% and V-1, respectively. The heat release rate (HRR), total heat release (THR), and average effective heat release (av-EHR) decrease in conical calorimetry. The composite also exhibits good carbon forming capacity. The flame retardation mainly originates from cooperation of condensation phase with gas phase process. Since the poor miscibility limit the dispersibility of COPD in PLLA matrix, the flame resistance and mechanical performance of composite are to compromised. The flame retardation for PLLA is anticipated due to green raw material is used and alternative process such as melt blending and adding compatibility can be adopted.