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 aspolymerized PLLA and Al(OH)3 themselves, which makes the melt processing of the composite easier. Nevertheless, at temperatures lower than 300 (degree)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.