Reactive extrusion (REX) for PLA and PLA copolymer based nanocomposites (AIMPLAS, ES)

The core of the REX PL11 consists in a twin-screw extruder with 27 mm of screw diameter and L/D ratio of 56, equipped with several side feeders, vacuum venting, and liquid injection ports, that will be used as a continuous reactor for polymerization of PLA and its copolymers by Ring Opening Polymerization (ROP) of lactide. The main advantages of the REX process compared to standard batch approaches is a faster polymerization (from hours to a few min), the ability to work in a continuous mode, showing better mixing/dispersion capacity, and making easier to handle high viscosity materials in a free or almost free solvent process. The polymerization of PLA and its copolymers will be carried out in presence of NPs obtained in other PLs, thus allowing the in-situ polymerization of PLA nanocomposites to be extruded into pellets. The production capacity will range up to 10 kg/h. REX conditions will be applied in a co-rotating twin screw extruder where the final process parameters (screw and extruder configuration, T profile, throughput, and residence time) will be optimized.

pilot lines templates image
pilot lines templates image

Different twin screw extruders are available (L/D ratio 44-56) with several side feeders, vacuum venting, injection ports for liquids/gases, feeders. Software tools to screw simulation will support the process design to achieve productions of 4-8 kg/h. In terms of in line monitoring of REX, a similar approach will be followed as for LIST, adjusting the monitoring points and spectral range to the specificity of the PLA reaction process (e.g. FT-MIR could be needed to obtain a fine tracking of the extent of the reaction.