Flow visualization and study of chemical reactions in a modular intermeshing co-rotating twin screw extruder

This dissertation presents the first integrated study of chemical reaction engineering in a complex modular twin screw extruder. It combines 4 sections: (i) Studies of flow visualization and residence time distribution in specially built twin screw extruder. (ii) Studies of reaction rates of trans-esterification process in a batch reactor. (iii) Experimental study of trans-esterification in a modular reactor with various modular screw configurations. (iv) Development of testing of composite reactor models for the modular twin screw reactor.; A laboratory modular intermeshing co-rotating twin screw extruder was designed and constructed. This machine contains glass windows that allow us to perform flow visualization and outlet ports which allow material to be sampled. Flow in screw elements, screw combinations, and mixing effects in kneading discs, were observed through glass windows mounted on the upper barrel.; Residence time distributions were determined in this machine for modular screws with different screw and kneading disc arrangements. The relationship of residence time distribution with the position along the screw axis was also emphasized.; Trans-esterification reactions for ethylene-vinyl acetate copolymer and torque measurements were conducted in a batch internal mixer with varying temperature as a function of reaction time. The chemical kinetic rate constants and the equilibrium conditions were determined in the batch mixer experiments.; The same chemical reaction was carried out also in the twin screw extrusion unit that the author had built as described in the opening paragraph. Different modular screw combinations were used. Samples were taken at three different points along the screw axis. The extents of chemical reaction for various screw arrangements with different residence time distribution were determined. We have also modeled simultaneous fluid mechanics and reaction phenomena in the twin screw extruder for different sets of processing variables. This modeling involves use of composite models for the screw, kneading disc blocks, and the die section.