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Melt Polymerization Reactor


The Buchi 5L melt polymerization reactor is used to synthesize polycondensation polymers (e.g. PEF, PET, PBS) via melt polymerization on a lab scale (up to a few kilogram). The polycondensation reaction involves two steps: i) the transesterification of monomers under inert atmosphere, followed by ii) the molecular weight build-up at high vacuum. A condensate is formed during the first stage, typically water or methanol depending on the monomers used, that has to be removed by distillation to drive the reaction to completion. The viscosity of the polymer melt increases strongly during the second phase of the reaction due to the molecular weight build-up of the polymer. Once a certain viscosity (or torque) is obtained, the reaction is stopped. The polymer is extruded from the reaction vessel via the heated bottom drain valve by applying inert gas, cooled in a water bath to a solid strand and optionally pelletized.  

Technical Details

  • 5L stainless steel reactor vessel equipped with helicoil or anchor stirrer and heated bottom drain valve.
  • Powerful magnetic coupling agitator with a maximum torque of 3600 Ncm .
  • Pressure range from full vacuum up to 10 bar.
  • Temperature range in vessel up to 300 °C.
  • Glass distillation system with a spiral condensor and 4L receiving flask.
  • Systag ePILOT software to automate temperature and pressure profiles of the reaction.


The synthesis of polycondensation polymers via melt polycondensation.

Last edited by Oscar de Vos on 2023-04-04

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Evelien Maaskant-Reilink
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