Microwave energy assisted synthesis of poly lactic acid via continuous reactive extrusion: modelling of reaction kinetics

Abstract

The most commonly used batch process to manufacture PLA is ring opening polymerization (ROP) of lactide monomer in a suitable solvent, in the presence of a metallic/bimetallic catalyst (Sn, Zn, and Al) or other organic catalysts. However, this process does not lend itself to safer/cleaner and high throughput (and high volume) manufacturing. Continuous reactive extrusion of lactide monomer using a suitable reaction input has the potential to increase the throughput, and this route has been explored in the literature. In this work, reactive extrusion experiments using stannous octoate Sn(Oct) 2 and tri-phenyl phosphine (PPh) 3 , were considered to perform ROP of lactide monomer using the microwave as an alternative energy (AE) source for activating and/or boosting the polymerization. Implementation of a microwave generator in a section of the extruder is one of the novelties of this research. A simulation model of ROP of PLA was formulated to estimate the impact of reaction kinetics and AE source on the polymerization process. Ludovic® software was used for the simulation of continuous reactive extrusion of the process. Experimental and simulated results were compared for the validation of the methodology. This work also highlights the advantages and drawbacks of most conventional metal catalysts, the effect of alternative energies on reaction mechanism, and safe and efficient production of PLA.

Macromolecular Dyes by Chromophore-Initiated Ring Opening Polymerization of L-Lactide

“…Finally, lactide, lactic acid, and its oligomer are polar molecules so they can absorb microwave energy, thus increasing the temperature of the reaction [ 19 ]. In the literature, there are few examples that use a co-initiator in the preparation of PLA by microwave irradiation [ 52 , 53 , 54 ], and to the best of our knowledge, FM that is a chromophore, is for the first time used as a co-initiator in the ROP of L-lactide under microwave irradiation. Experimental details for the preparation of macromolecular dyes end capped with FM prepared by microwave-assisted polymerization of L-lactide (MDFMmws) are reported in the Supplementary Materials .…”

Quantitative evaluation of the non-thermal effect in microwave induced polymer curing

“…Integral isoconversional methods originate from the application of the iso-conversional principle to the integral equation. [32][33][34][35] An analytical eqn (2) is obtained for an isothermal temperature program:…”

Progress in environmental-friendly polymer nanocomposite material from PLA: Synthesis, processing and applications

“…Dubey et. al [71] also investigated in detail the reaction mechanism and suitability of microwave for the polymerization of Lactide through an extrusion process. In this work, demonstration of the initial experimental process and its application to the mathematical model was well described.…”

“…The reaction kinetic information for PLA formation in the extrusion reaction process by taking a combination of the metal catalysts and AE sources has also been revealed by Dubey et.al. [71].…”