ARTICULOS DE QUIMICA

15/9/2 187850 EMA Number: 199905-D1-P-0593 On-line optimization of free radical bulk polymerization reactors in the presence of equipment failure. Saraf, D N ; Gupta, S K ; Garg, S Indian Institute of Technology (New Delhi) Journal of Applied Polymer Science , 71, (12) , p. 2101-2120 ISSN: 0021-8995 Publication Date: 21 Mar. 1999 USA , 1999 1999 Country of Publication: USA Journal Announcement: 9905 Document Type: Article Language: ENGLISH
An on-line optimizing control scheme has been developed for bulk polymerization of free radical systems.
The effects of random errors, as well as one kind of a major disturbance (heating system failure), have been studied. A model-based, inferential state estimation scheme was incorporated to estimate, on-line, the parameters of the model (and thereby, the monomer conversion and molecular weight of the polymer) using experimental data on temperature and viscosity. A sequential quadratic programming technique was used for this purpose. A major disturbance, such as heating system failure, leads to a deteriorated final product unless an on-line optimal temperature trajectory (history) is recomputed and implemented on the reactor. Genetic algorithm was used for this purpose. It has been found that, if the 'sensing' of the major temperature deviation from the optimal value and rectification of the heating system is achieved well in advance of the onset of the Trommsdroff effect, use of a reoptimized temperature history is sufficient to produce the desired product without significantly altering reaction time. However, if such a disturbance occurs late, a single-shot intermediate addition of an optimal amount of initiator needs to be used in addition to changing the temperature history to produce polymers having the desired properties in the minimum reaction time. Other types of failures can similarly be handled using the methodology developed. (Example material: pmma.) Numerical Data; Graphs. 29 ref. Descriptors: Journal Article; Polymethyl methacrylates-- Polymerization; Bulk polymerization; Free radical polymerization; Process parameters; Reaction kinetics; Chemical reactors-- Design; Process control; Control systems; Sensors; Temperature measurement; Mathematical models Section Headings: D1 Raw Materials; B2 Testing & Quality Control Subfile: P Polymers Eng Materials Abs(R) (DialogŪ File 293): (c) 2000 Cambridge Scientific Abs. All rights reserved.

15/9/12 103844 EMA Number: 199205-D1-P-1040 Continuing Initiator System Developments Provide a New Horizon for Polyolefin Quality and Properties. Galli, P ; Haylock, J C Three Little Falls Center Progress in Polymer Science , 16, (2-3) , p. 443-462 ISSN: 0079-6700 Publication Date: 1991 1991 1991 Country of Publication: UK Journal Announcement: 9205 Document Type: Article Language: ENGLISH
The history of Ziegler--Natta initiator systems is reviewed and new developments in the field are described. First-, second- and third generation systems are detailed. Control of both the morphological structure of the "reactor granule" and the polymerization mechanism resulted from research that has led to a significant, fundamental advance in the understanding of Ziegler--Natta polymerization. Heat transfer plays an important role in the initiator granule's initial "explosion" and subsequent growth. The formation of an outer, continually growing polymer skin provides a reaction bed within which copolymer, terpolymer or multimonomer olefinic polymer systems can be produced through the introduction of other monomers to the internal active sites during the polymerization process. Novel copolymers, alloys and blends which have been produced are also described. These include: polypropylene random copolymers, impact copolymers and unique, high melt flow reactor-made resins for non-woven fiber applications. Photomicrographs; Graphs. 39 ref. Descriptors: Journal Article; Polypropylenes-- Synthesis; Ziegler-Natta process; Copolymerization; Blending Section Headings: D1 Raw Materials Subfile: P Polymers Eng Materials Abs(R) (DialogŪ File 293): (c) 2000 Cambridge Scientific Abs. All rights reserved.

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