Intensification of Polymerization Processes by Reactive Extrusion

Abstract

The unique geometry of screw extruders allows handling very viscous media; thus, they can be used as continuous reactors to conduct polymerization reactions without using any solvents. This is called reactive extrusion polymerization. It is an intensified process as it maximizes reaction rates upon maximizing the concentrations of monomers and an initiator/catalyst (if there is any). It also allows conducting polymerization reactions at higher temperatures, without having to take measures to prevent solvents from evaporating or to work under pressure. However, screw extruders are not suitable for the early stage of polymerization in which the viscosity of the polymerization system may not be high enough for the rotation of the screws to generate a steady flow. A combination of continuously stirred tank reactors and a twin-screw extruder or several in series is preferred for the polymerization process. This review shows how reactive extrusion may intensify different types of polymerization processes under the constraint of no solvents, such as free-radical polymerization, anionic polymerization, ring-opening polymerization, and polycondensation, on one hand; and how challenges are met, on the other hand.

Effect of curing time on the mechanical properties of poly(glycerol sebacate)

“…The literature shows that flow may significantly accelerate the reaction. [23][24][25] Adding prepolymer to Teflon dishes using pipette and the dishes were transferred to a vacuum oven set at 130 C under 0.1 kPa. After 24 h, 36, 48, 60, 72, 84, and 96 h, the PGS samples were taken out.…”

Synthesis and evaluation of epoxidized vegetable oleic acid as a novel environmental benign plasticizer for polyvinyl chloride

“…The composition of PVC samples was shown in Table 2. An alternative process is melted compounding using an internal mixer 33–35 or a twin screw extruder 36,37 . Since melt compounding does not use any solvents, it is much more environmentally benign and industrially more relevant.…”

Mechanochemical Applications of Reactive Extrusion from Organic Synthesis to Catalytic and Active Materials

“…The main applications of extrusion can be found in polymer manufacturing, especially in the dispersion of materials into polymers [28]. Reactive extrusion (REX) [29] is used to synthesize polymers and to carry out post synthetic polymer modification (e.g., functionalization of polymer chains) via organic transformations that alter the properties of materials [30]. Moreover, these modifications can be achieved via four different REX processes: (i) grafting reactions; (ii) functionalization; (iii) controlled degradation; (vi) blending and reactive blending [31].…”