The combustion process of virgin and reprocessed polylactide (PLA) was simulated by multi-rate linear non-isothermal thermogravimetric experiments under O2. A complete methodology that accounted on the thermal stability and emission of gases was thoroughly developed. A new model, Thermal Decomposition Behavior, and novel parameters, the Zero-Decomposition Temperatures, were used to test the thermal stability of the materials under any linear heating rate. The release of gases was monitored by Evolved Gas Analysis with in-line FT-IR analysis. In addition, a kinetic analysis methodology that accounted for variable activation parameters showed that the decomposition process could be driven by the formation of bubbles in the melt. It was found that the combustion technologies for virgin PLA could be transferred for the energetic valorization of its recyclates. Combustion was pointed out as appropriate for the energetic valorization of PLA submitted to more than three successive reprocessing cycles.
Bibliographical noteThe authors would like to acknowledge the Spanish Ministry of Science and Innovation for the financial support through the Research Projects ENE2007-67584-C03, UPOVCE-3E-013, ENE2011-28735-C02-01, IT-2009-0074, as well as for the pre-doctoral research position for L. Santonja-Blasco through the FPI program. The Spanish Ministry for Education is acknowledged for the concession of a pre-doctoral research position to J.D. Badia and A. Martinez-Felipe by means of the FPU program. The authors thank the financial support of the Generalitat Valenciana through the ACOMP/2011/189, the Grisolia research position for A. Martínez-Felipe, and for the Forteza technician position. Universitat Politècnica de València (UPV, Spain) is thanked for additional support through the PAID 05-09-4331 and PAID 06-11-2037 projects. AIMPLAS (Technological Institute of Plastic) is acknowledged for providing and processing the material.
- energetic valorization
- Polylactide (PLA)
- thermal stability
- Thermo-oxidative decomposition kinetics
- evolved-gases analysis (EGA)