Polylactic acid (PLA) is a polymer produced from biological feedstock that can displace conventional petroleum-derived polymers. There is presently a limited academic understanding of its production from lactic acid, which can be attributed to complex reaction kinetics, physical properties, and stereochemistry. In this work, we apply an original modeling approach to produce the first detailed process model for the production of optically pure PLA from lactic acid. We describe the importance of vapor–liquid and solid–liquid equilibria and how phase equilibria constrain operation, characterize the stereoisomer balance, and demonstrate how mass transport limits the lactide reactor and PLA devolatilization. We present a design for the combined process from lactic acid to PLA pellets with a detailed evaluation of energy inputs that compares reasonably with the primary energy consumption of nonrenewable resources reported in industrial life-cycle analysis.
McNeeley et al. (Sat,) studied this question.