<p> The work in this thesis focuses on the temperature control of a semi-batch polymerization reactor. The system is published by Chylla and Haase (1993) as an Industrial Challenge and is typical of reactors at S.C. Johnson Wax. The challenge is to find a single controller that can adequately regulate reactor temperature despite changing process conditions. The multi-product nature of the system makes it a particularly interesting problem. Several different controllers are implemented and evaluated in this thesis. The controllers are in part chosen to quantify the amount process information (large or small) required in a controller structure in order to achieve satisfactory control. Two of the most promising controllers are a PID with feedforward compensation and a Nonlinear Adaptive algorithm. It is found that in many cases, there may be little incentive to go to a complex model based controller as the simpler feedback algorithm provides adequate control. However, the nonlinear adaptive controller is more easily extended to multi-batch or multi-product situations because of its more general nature. The PID with feedforward compensation requires retuning for each new situation in order to maintain satisfactory control. </p> / Thesis / Master of Engineering (MEngr)