Flame retarded poly(lactic acid): A review

Poly(lactic acid) (PLA) synthesized from renewable resources has drawn a great deal of interest in packaging, electronics and automotive applications. However, poor flame retardancy of PLA, especially its ease of ignitability and heavily flaming drips, represents a major obstacle for its potential application. The article outlines the recent advances in the field of flame-retarded PLA. Current development trends based on the direct incorporation of flame retardant additives, chemical modification, hybridization and synthesis of flame retardants were reported. Results obtained from UL 94 vertical burning, limiting oxygen index (LOI) and cone calorimetry (CCM) tests for each type of flame retardants were discussed and analyzed. Test results summarized in a UL 94-LOI matrix found to be a useful tool to determine the effectiveness of flame retardants in PLA. The UL 94-LOI comparison matrix and CCM test results revealed that the combined use of flame retardants (containing intumescent formulation) is one of the promising strategies to reach the flame retardancy of PLA needed by practical applications. This review ends with a brief summary of and outlook on future developments of flame-retarded PLA systems.