Polymerization Reactors: Summary
The answers to the ConcepTests are given below and will open in a separate window.
Key points from this module:
- The type of reactor has a large influence on the molecular weight distribution (MWD) for a polymer.
- The MWD is affected by the residence time distribution of the reactor, the concentration at which reaction takes place, and the chain growth time of the polymerization.
- For condensation polymerization, the chain growth time can be greater than the mean residence time.
- When the chain growth time > mean residence time, a PFR or batch reactor will have a narrower MWD than a CSTR because all molecules have the same reaction time in a PFR or batch reactor.
- For free radical polymerization, the chain growth time is usually much less than the mean residence time.
- When the chain growth time < mean residence time, a CSTR will have a narrower MWD than a PFR or batch reactor because all reaction in a CSTR takes place at the same monomer concentration.
- The moments for a polymer are a way to characterize the polymer distribution.
From studying this module, you should now be able to:
- Decide what type reactor should be used for a particular polymerization.
- Explain how residence time distribution affects molecular weight distribution.
- Calculate mass balances for polymerization in a CSTR.
Prepared by John L. Falconer, Department of Chemical and Biological Engineering, University of Colorado Boulder