Experimental studies of diethyl adipate saponification in a CSTR show that forced cycling of feed composition produces significant yield increases in intermediate product relative to the optimal steady state operation, while forced temperature cycling has much less effect. Related experiments provide useful transient heat transfer data for this system. Reaction kinetics have been determined in water and in a 5070 (v/v) isopropanol solvent.onsecutive-competitive reactions are of great in-

The interaction between imperfect mixing and cyclic operation is examined for several continuous polymerizations in stirred-tank reactors. The reactor is represented by a mixed model involving two interconnected ideal stirred vessels. Cyclic fluctuations in the concentration of a chain transfer agent during Ziegler-catalyzed olefin polymerization can yield molecular weight distributions significantly different from those of a conventional steady state reactor. This result is consistent with the available experimental data. It is especially interesting that the cyclic reactor effluent with a modified molecular weight distribution is of approximately timeinvariant composition when the period of cycling is on the order of the reactor holding time. Imperfect mixing has a lesser effect on cycled reactors for free-radical and polycondensation polymerization than it has on cycled olefin polymerization reactors. C. K. LEE and J. E. BAILEY Department of Chemical EngineeringUniversity of Houston Houston, Texas 77004 SCOPEIt is well known that the degree of mixing within a polymerization reactor can significantly affect the product molecular weight distribution (MWD) and thereby the polymer properties. Similarly, intentional unsteady operation of such reactors by varying such operating parameters as feed concentrations or flow rate can produce different MWD's than any steady state operation. This result has been obtained in modeling studies by Ray (1968) for free-radical and polycondensation polymerizations,.;for example, and demonstrated experimentally by Claybaugh et al. (1969) for Ziegler-catalyzed olefin polymerization. Since commercial reactors may not be perfectly mixed, the objective of this work is to analyze the combined effects of imperfect mixing and cyclic operation.