Simulation of Nonlinear Polyurethane Production in a Twin-Screw Extruder

The production of nonlinear polyurethane from the reaction of methyl diisocyanate (MDI) with a mixture of a polyester and 1,4-butanediol was studied in a closely intermeshing, counter-rotating twin-screw extruder, using an ideal reactor model consisting of a series of continuous stirred tank reactors (CSTR) coupled to a previously developed kinetic-probabilistic model. The kinetic part of the model allows for the calculation of concentrations of all species. A recursive probabilistic model is used to calculate the number and weight average molecular weights. Allophanate reactions, as well as gel formation due to crosslinking, are considered in the model. Pressure, flow rate, and polymer properties along the extruder can be calculated with the model.

Keywords:

• Reactive extrusion
• Polyurethane
• Crosslinking
• Twin-screw extruder
• Modeling

ACKNOWLEDGMENTS

The authors wish to acknowledge financial support through research project grants from the National Council for Science and Technology (CONACYT) of Mexico to E.V.-L. and O.M., and the graduate scholarship granted to R.O.V. by CONACYT. Financial support from DGAPA-UNAM, through project PAPIIT IN106302, is also acknowledged.