An engineering analysis of the reactive extrusion process of a thermoplastic polyurethane was made through numerical simulation. The reactants used in this system were 4,4'-diphenylmethane diisocyanate, polycaprolactone diol (M.W.; 824) and 1,4-butanediol with equivalent weight ratio of 2:1:1. As a catalyst, dibutyltin dilaurate was used.
The reaction kinetics and the viscosity function were obtained through experiments and the mathematical model which includes the conservation equations of mass, momentum, energy and chemical species was solved numerically to obtain the velocity, concentration, temperature, viscosity and pressure profiles.
The conservation equations were solved numerically by the two different algorithms and the differences between the two methods were discussed. One of the above algorithms is to use the concept of residence times in an extruder channel and the other is to use the concept of average history of the particles with different flow paths in the channel.
The importance of the shear rate dependence of viscosity in the reactive extrusion process was discussed, especially at high conversion.
The effects of the operating parameters, such as the catalyst concentration, flow rate, screw speed, screw temperature, barrel temperature and channel depth, on conversion profiles were investigated to obtain reasonably uniform distribution of the conversion (or molecular weight) across the channel.
The actual experiments were performed to compare the experimental results with those of the numerical simulation. The flow rate, screw speed and barrel temperature were selected as the operating An engineering analysis of the reactive extrusion process of a thermoplastic polyurethane was made through numerical simulation. The reactants used in this system were 4,4'-diphenylmethane diisocyanate, polycaprolactone diol (M.W.; 824) and 1,4-butanediol with equivalent weight ratio of 2:1:1. As a catalyst, dibutyltin dilaurate was used.
The reaction kinetics and the viscosity function were obtained through experiments and the mathematical model which includes the conservation equations of mass, momentum, energy and chemical species was solved numerically to obtain the velocity, concentration, temperature, viscosity and pressure profiles.
The conservation equations were solved numerically by the two different algorithms and the differences between the two methods were discussed. One of the above algorithms is to use the concept of residence times in an extruder channel and the other is to use the concept of average history of the particles with different flow paths in the channel.
The importance of the shear rate dependence of viscosity in the reactive extrusion process was discussed, especially at high conversion.
The effects of the operating parameters, such as the catalyst concentration, flow rate, screw speed, screw temperature, barrel temperature and channel depth, on conversion profiles were investigated to obtain reasonably uniform distribution of the conversion (or molecular weight) across the channel.
The actual experiments were performed to compare the experimental results with those of the numerical simulation. The flow rate, screw speed and barrel temperature were selected as the operating parameters. In the experimental work, maximum run time was measured for the steady operation.parameters. In the experimental work, maximum run time was measured for the steady operation.
