Kinetic Simulation Analysis of Thermal Degradation of Poly(lactic acid)/Polycarbonate Blends for Chemical Recycling

Abstract

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 spectrometry, 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(II) oxide (SnO) 1 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 310°C. Therefore, it was confirmed that PLLA/PC blend is a selectively chemically recyclable material.