Off-campus UMass Amherst users: To download dissertations, please use the following link to log into our proxy server with your UMass Amherst user name and password.
Non-UMass Amherst users, please click the view more button below to purchase a copy of this dissertation from Proquest.
(Some titles may also be available free of charge in our Open Access Dissertation Collection, so please check there first.)
The design of continuous polycondensation reactors
Abstract
A simplified approach to polycondensation kinetics has been used to develop engineering models for the design of film-forming polycondensation reactor-separators. This approach has been applied to a nylon 6,6 prepolymer in an idealized flowing film device. The model is characterized by two dimensionless groups; the Damkohler number and the Thiele modulus. A realistic kinetic and equilibrium description was incorporated with an activity-based kinetic model with composition-dependent apparent rate and equilibrium constants. The model is suitable for evaluating the effect(s) of changes in throughput, flow, film thickness, temperature and catalyst reactivity on the device performance. Since nylon 6,6 is typically used for fibers, molecular weight is not the only important product property. It must also have the proper balance of end-groups for good dyeability and very small amounts of gelled material for fiber spinning. A simplified thermal degradation model that is consistent with available data has been formulated to predict the amount of degraded material in the final product. The importance of the residence time distribution on the amount of degradation in the flowing film device has demonstrated. Finally, a realistic wiped film model for the design and performance analysis of continuously mixed thin-film nylon 6,6 "finishing" reactors has been constructed. The model incorporates composition dependent rate and equilibrium constants, a realistic degradation scheme and a finite gas-phase concentration. Even small amounts of mixing have been shown to yield very large improvements in both the mass transfer and molecular weight generation in such film reactors.
Subject Area
Polymers
Recommended Citation
Steppan, David Daniel, "The design of continuous polycondensation reactors" (1989). Doctoral Dissertations Available from Proquest. AAI8917409.
https://scholarworks.umass.edu/dissertations/AAI8917409