CONTINUOUS SYNTHESIS OF ADDITION POLYMERS WITH A PRECISELY CONTROLLED AVERAGE MOLECULAR WEIGHT AND MINIMUM POLYDISPERSITY

A novel technique for the control of continuous synthesis of addition polymers with precisely controlled average molecular weight and minimum polydispersity has been developed. A control system adjusts the concentration of chain‐transfer agent in the reactor feed to compensate for all other upsets, in the reactor inputs: initiator and monomer concentrations, temperature and feed rate. The technique has been evaluated quantitatively on a digital computer using a kinetic model of homogeneous, free‐radical solution polymerization. In computational tests, the modeled control system generally held the instantaneous number‐average chain length within 1%, and quickly returned it to the desired value in response to a wide variety of upsets. By generalizing the Schulz distributions to include termination by disproportionation, combination and chain‐transfer, it is shown that changes in the molecular‐weight distribution resulting from the action of the control system are minor. Copyright © 1969 John Wiley & Sons, Inc.