NONLINEAR TRACKING OF GLASS-TRANSITION TEMPERATURES FOR FREE-RADICAL EMULSION COPOLYMERS

Citation
G. Fevotte et al., NONLINEAR TRACKING OF GLASS-TRANSITION TEMPERATURES FOR FREE-RADICAL EMULSION COPOLYMERS, Chemical Engineering Science, 53(4), 1998, pp. 773-786
Citations number
33
Categorie Soggetti
Engineering, Chemical
ISSN journal
00092509
Volume
53
Issue
4
Year of publication
1998
Pages
773 - 786
Database
ISI
SICI code
0009-2509(1998)53:4<773:NTOGTF>2.0.ZU;2-I
Abstract
A new method for the control and estimation of the glass transition te mperature (T-G) of free-radical copolymers is presented, and is intend ed to improve the on-line control of the quality of these products. As an example of this approach, a non-linear control law is used to mani pulate the monomer feed flow rate of semi-batch copolymerisation in em ulsion in order to pursue a predefined trajectory of T-G. The measured output required for an effective closed-loop system is provided throu gh calorimetric measurements of the overall monomer conversion, and bo th the number of moles of monomer and the total number of radicals in the polymer particles are estimated using non-linear observation techn iques. The global approach is based on a simplified kinetic model of t he emulsion copolymerisation of water-insoluble monomers, which was va lidated through laboratory scale experiments. In addition to the overa ll and partial conversions, the model also predicts the time variation s of the instantaneous copolymer composition and T-G and of the averag e particle size. The state and parameter observer was evaluated with b oth simulated and real polymerisation data, and is shown to perform ve ry well. The tracking ability of the non-linear control strategy was f ound to be robust and accurate despite uncertainty and noise in both t he simulated model and experimental measurements. (C) 1998 Published b y Elsevier Science Ltd.