Synergistic effect of organo-montmorillonite on intumescent flame-retardant PLA

Organo-montmorillonite (OMMT) is utilized as a synergistic agent in poly (lactic acid) (PLA) intumescent flame retardant (IFR) system. The thermal and combustion behavior of PLA intumescent systems have been investigated by using thermogravimetric analysis (TGA), limiting oxygen index (LOI), vertical burning test and cone calorimeter test (CCTs). Compared with pure PLA, the addition of IFR can apparently develop the thermal stability and fire property, furthermore, OMMT can endow the PLA intumescent samples with better thermal performance and flame retardancy, exhibiting a distinct synergistic effect with IFR, which is demonstrated by LOI value, UL-94 rating, Heat release rate (HRR) and Total heat rate (THR), respectively. SEM results show that a small amount (1 wt%) of OMMT not only increased the content of char residue, but also enhanced the strength of intumescent char barrier, forming a compact and folded structure.