The fire performance of polylactic acid containing a novel intumescent flame retardant and intercalated layered double hydroxides
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In this work, a novel single macromolecular intumescent flame retardant (DT-M) was prepared by self-assembly of diethylenetriamine penta-(methylenephosphonic) acid with melamine, and modified layered double hydroxides (LDH) were also prepared by intercalating phytic acid into LDHs. The chemical structures of DT-M and phytic acid intercalated LDHs (PA–LDH) were fully characterized by different analytical instruments, and then were introduced into PLA by melt compounding to prepare a flame retardant biodegradable PLA composite. The fire performance evaluation of PLA composites by limiting oxygen index (LOI), vertical burning (UL-94) and cone calorimeter tests indicated that the introduction of 14% DT-M and 1% PA–LDH increased the LOI value from 19.4 to 38.9%, upgraded the UL-94 rating from no rating to V-0, and decreased the peak heat release rate from 812 to 301 kW m−2. The analysis for decomposition products of PLA composite and the observation of morphology of the char suggested that DT-M and PA–LDH took effects in both condensed phase through promoting char formation and gas phase through releasing inert gases.
This work was financially supported by National Natural Science Foundation of China (Grant No. 21674008) and Beijing Natural Science Foundation (Grant No. 2174083).