Reactive extrusion of intumescent stereocomplexed poly-L,D-lactide: characterization and reaction to fire

This paper reports works conducted on intumescent stereocomplexed polylactide synthesized for the first time by reactive extrusion. This reactive extrusion process is an innovative, efficient and ecofriendly way to product polylactides. This stereocomplexed polylactide results from the two-step polymerization of L-lactide and D-lactide to yield poly-L,D-lactide multiblocks. Our reactive extrusion process permits to make polylactide matrix able to form stereocomplex crystallinity and to incorporate flame-retardant additives during synthesis at the same time. This material can be molded keeping its stereocomplex crystallinity. The flame retardants which are a combination of ammonium polyphosphate, melamine and organoclay provide an intumescent behavior upon heating to the stereocomplex, and the flame-retarded material exhibits very low flammability (peak of heat release rate is decreased by 83% and total heat released is decreased by 95% during cone calorimetry experiment). Copyright (C) 2012 John Wiley & Sons, Ltd.