Feedstock Recycling of Flame-Resisting Poly(lactic acid)/Aluminum Hydroxide Composite to l , l -lactide

To achieve the chemical recycling of flame-resisting materials consisting of poly( l -lactic acid) (PLLA), a safer flame-resisting material, PLLA/aluminum hydroxide {Al(OH) 3 } composite, was investigated the capability of the feedstock recyclability to optically active monomer l, l -lactide. The thermal stabilization of the composite was improved compared to those of as-polymerized PLLA and Al(OH) 3 themselves, which makes the melt processing of the composite easier. Nevertheless, at temperatures lower than 300 °C the effective depolymerization of PLLA proceeded, without any racemization reaction, to selectively convert into l, l -lactide, with Al(OH) 3 acting as a catalyst for the depolymerization. This means that the PLLA/Al(OH) 3 composite is capable of reconciling flame resistance with feedstock recycling of PLLA to cyclic monomer.