Kinetic simulation analysis of thermal degradation of poly(lactic acid)/polycarbonate blends for chemical recycling

Thermal degradation behavior of poly-L-lactic acid (PLLA)/bisphenol-A type polycarbonate (PC) blends was investigated to recover cyclic monomer L,L-lactide selectively. Effects of catalysts and heating conditions on the degradation were analyzed by thermogravimetry and pyrolysis-gas chromatography/mass spectrometiy, followed by detailed kinetic simulation. It was suggested that PLLA and PC ingredients interact with each other during the degradation process, inducing racemization and random degradation. When tin(Il) oxide (SnO) I wt % was used as a catalyst, the thermogravimetric curve of PLLA/PC blend approximated a two-step weight loss profile and an ideal selective recovery of L,L-lactide was achieved at temperatures below 310C. Therefore, it was confirmed that PLLA/PC blend is a selectively chemically recyclable material. © 2013 The Society of Polymer Science, Japan.