The Preparation of an Intumescent Flame Retardant by Ion Exchange and Its Application in Polylactic Acid

Owing to the biological compatibility and mechanical properties of polylactic acid (PLA), it presents an extensive application area (such as packaging, film, and fiber). However, the molten dripping phenomenon during combustion is still a drawback in the application of PLA. In this research, an intumescent flame retardant (A-A) was prepared based on the ionic exchange between p-aminobenzenesulfonic acid and ammonium polyphosphate. After that, A-A was molten compounded with PLA to improve its flame retardancy. It was suggested that the presence of 15% A-A could increase the limiting oxygen index value from 20.0% of neat PLA to 30.5%, enhance the UL results from none to V-0 and restrict the heat release during cone calorimeter test. Most importantly, the dripping behavior of PLA/15A-A composites while burning had been greatly minimized. On the basis of the mechanism analysis, it was suggested that A-A modified the initial degradation routine of PLA matrix, resulting to the rapid construction of protective barrier, thus endowing the antidripping property to the PLA/15A-A composites.