SynopsisThis paper gives the results of the estimated coagulum content in the final sample of a dispersion based on styrene-butylacrylate-acrylic acid, prepared by semicontinuous emulsion polymerization. The results were gained from experiments on 25 L and 5 m3 reactors. The dependence of the amount of coagulum on the agitation intensity was studied. It was found that it is necessary to divide the results into two regions: (a) for specific power input smaller than 80 W/m3; (b) for specific power input greater than 80 W/m3. It was found that polymerization scaling up from the point of constant coagulum content in the system studied is possible under the conditions of constant specific power input. The specific power input varied in the range from 5 to 3000 W/m2. For the first region was gained the empiric correlation Y = 2.16(gV)-' and for the second region the equation Y = 3.5 X 10-5(8v)1.5, where Y is the amount of coagulum (wt W).For the existence of two regions we propose the following hypothesis according to which increasing mixing intensity improves the temperature and concentration nonuniformity which results in the decrease of coagulum content. From the certain value of specific power input, which is specific for each system, the amount of coagulum starts to increase due to increasing shear stress.
SynopsisThis article deals with the alkaline hydrolysis of ethyl acrylateacrylonitrile-divinylbenzene copolymer beads. Chemical changes during hydrolysis were evaluated by means of determination of total weight exchange capacity and of infrared spectroscopy. The influence of reaction temperature, concentration of the hydrolytic agent, degree of copolymers crosslinking as well as the influence of particle size upon the rate of hydrolysis were studied as a function of time. The mathematical and statistical calculations of experimental data were carried out. With respect to time dependence of hydrolysis of the copolymer functional groups, the average values of reaction rate constants as well as the values of assumed diffusion coefficients were calculated. The analysis is based on partial linearization of experimental results by means of semilogarithmic transformation. The empirical relations expressing dependences of reaction rate constants and of diffusion coefficients on conditions of hydrolysis were determined. INTRODUCTIONThe alkaline hydrolysis of esters and nitriles in organic chemistry of lowmolecular compounds has been well described.' However, this is not the case for hydrolysis of polymers containing the mentioned groups and especially for crosslinked copolymers in bead form. Let us make reference to some preceding articles. The above problems are described for instance by Smets and his cO-workers,2-4 by Stamberg and Se~Eik,~ or by Hynkova and Hraba16J as well as in patent l i t e r a t~r e .~~~ From the point of view of reaction kinetics the system of solid copolymer particles suspended in the liquid reaction medium is rather complicated. The reaction systems solid-liquid, especially those concerning heterogeneous catalysis, are described, e.g., by Aris,l0 who deals with these questions, however, only from the theoretical point of view. He has shown that the mathematical models of reacting solids in the liquid reaction medium can be exactly used only for isolated examples with simplified assumptions. That is why we have decided to describe the obtained results by means of empirical relations applicable especially to this investigated system in the given range. PROBLEM ANALYSISContrary to the hydrolysis of monomer esters and nitriles which is affected by the reaction temperature and by the time and concentration of the hydrolytic agent, only in case of crosslinked copolymer beads there is another important factor, namely, hydrolytic agent diffusion into the mass of the hydrophobic skeleton, which is affected by the skeleton network density and by the copolymer particle size. It means therefore that the studied questions are determined by diffusion of reaction components into copolymer particles and by subsequent chemical reaction between the liquid reagents and reactive groups fixed to the crosslinked copolymer. The subject under discussion in our case are the ester and nitrile groups hydrolyzed by the aqueous solution of sodium hydroxide. This article represents the continuation of results obtained in cas...
ZUSAMMENFASSUNG:In dieser Arbeit wurde die h d e r u n g der Konzentration der Reaktionskomponenten mit der Zeit bei der Reaktion eines hOhermolekularen Epoxidharzes mit Tetrahydrophthalsaure-und 3-Chlortetrahydrophthalstiureanhydrid in Anwesenheit von Lauryldimethylbenzylammoniumbromid verfolgt. Diese Messungen wurden im technischen Manstab wie bei der Verarbeitung der Komponenten im Extruder gemacht.Die Reaktion wurde im Temperaturbereich von 363,2 -403,2 K, d. h. in der N&e des Erweichungspunktes des Harzes durchgeftkhrt. Die gemessenen Konzentrationswerte der einzelnen reagierenden Gruppen i m Reaktionssystem wurden in Abhtlngigkeit von der Zeit mit Hilfe der ftkr die Folgereaktionen nach zweiter Ordnung geltenden kinetischen Beziehungen ausgewertet. Diese Auswertung wurde in der Anfangsphase der Reaktion durchgeftihrt. Es zeigte sich beim Vergleich aller drei bei 383,2 K gemessenen Systeme, da8 das System mit 3-Chlortetrahydrophthalstiureanhydrid den grO8ten Wert der Geschwindigkeitskonstante kl = 8,397 * kg s-l mol-' (giiltig ftkr die Bildung von Monoestern) und den niedrigsten Wert der Geschwindigkeitskonstante k, = 1,345 * kg s-I mol-' (gtiltig fur die Bildung von Diestern und daher von der vernetzten makromolekularen Struktur) aufweist. SUMMARY:The change of time of the concentration of components in the reaction of the higher molecular epoxy resin with tetrahydrophthalic and 3-chlorotetrahydrophthalic anhydrides in the presence of lauryldimethylbenzyl ammoniumbromide was investigated. These investigations were carried out in correspondence with the technical conditions for the reaction components in extruder. The reaction was carried out in the temperature range of 363.2 -403.2 K, thus near the softening point of the resin. The measured values of concentration of the particular groups in the reaction were evaluated as time dependence by means of kinetic relations applicable to second order consecutive reactions. This evaluation was carried out in the initial phase of the reaction. In comparison of the three investigated systems measured at the temperature of 383.2 K, 3-chlorotetrahydrophthalic anhydride has the highest value of the reaction constant kl = 8.397 * lo-' kg s-l mol-' (applicable to the monoester forma-0 1986 Hilthig & Wepf Verlag, Basel
Die Bestimmung der Copolymerzusammensetzung bei der mehrstufigen chargenweisen Polymerisation mit Hilfe der Mayo‐Lewis‐Gleichung durch schrittweise Integration der entsprechenden Differentialgleichungen wird vorgestellt. Die Verwendung von zwei voneinander abhängigen Beziehungen für den Monomerumsatz, und zwar für den aktuellen sowie für den Gesamtumsatz, stellt eine Grundlage der vorgeschlagenen Methode dar. Der Integrationsschritt bleibt für die ganze Berechnung konstant. Das Ergebnis des angeführten Vorgangs ist ein Berechnungsschema für die Simulierung des Verlaufs einer mehrstufigen chargenweisen Polymerisation. Es ermöglicht, die Zusammensetzung der entstehenden Copolymeren annähernd zu berechnen. Die vorgeschlagene Berechnungsmethode wird anhand einer mehrstufigen chargenweisen Polymerisation des Gemisches Styrol/Ethylacrylat demonstriert.
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