Compatibilization and property enhancement of poly(lactic acid)/polycarbonate blends through triacetin-mediated interchange reactions in the melt

Tetrabutylammonium tetraphenylborate (TBATPB) and triacetin were added during extrusion to melt blends of polylactic acid (PLA) and polycarbonate bisphenol A (PC) through a reactive compatibilization approach in order to enhance the materialsʹ mechanical properties and thermal resistance. Dynamic mechanical thermal analysis revealed a new peak attributable to the glass transition temperature (Tg) of the PLA-PC copolymer at a temperature lower than the Tg typical of PC and higher than the Tg of PLA. The results of tensile tests, thermogravimetric analysis, differential scanning calorimetry, scanning electron microscopy, transmission electron microscopy, size exclusion chromatography, and NMR analysis for the compatibilized and uncompatibilized blends were, on the whole, in agreement with the formation of the PLA-PC copolymer due to the action of the TBATPB and triacetin during the short extrusion time. The mechanical behaviour, morphology, and thermal properties of the PLA/PC compatibilized blends were investigated as a function of composition, with the intention of broadening the utility of these biobased-blends. Finally, a general scheme for the reactions that occur during extrusion was proposed based on the experimental results.