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The effect of different peroxides as catalysts and different polyhydroxy compounds as reducing activators both in the presence and absence of metals in a standard emulsion copolymerization of butadiene and styrene has been determined. The results of this study further emphasize the importance of a careful balance of all ingredients in any reduction-activation system.

Cumene hydroperoxide decomposes near 100 °C. in reactive solvents but only slightly in stable solvents. The decomposition is not a simple first order reaction. The results may be interpreted as the sum of a first and a three-halves order reaction. Approximate over-all energies of activation of the decomposition determined from the data obtained for the decomposition in cumene (31 kcal. per mole), methanol (31 kcal. per mole), styrene (20 kcal. per mole), and the energy of activation for the initial unimolecular step in benzene–styrene mixtures (30.4 kcal. per mole) agree with the values reported for similar peroxides and hydroperoxides in similar solvents. The energy of activation for the radical-induced decomposition is 6.5 kcal. per mole. The data suggest that the first step of the decomposition is the unimolecular reaction involving scission of the O–O bond. If the resultant C6H5C(CH3)2O∙ radical is not reactive towards the solvent, it tends to lose either a phenyl or a methyl radical and form acetone or acetophenone respectively. The former reaction predominates. The decomposition rapidly becomes autocatalytic, particularly in cumene at higher temperatures, presumably because of the radical-induced decomposition of the hydroperoxide. The identified products of decomposition in cumene can be explained by the various reactions of the radicals formed in the mixture. The polymerization shortstop 2,5-ditertiarybutylhydroquinone reacts rapidly below 0 °C. with an equimolar weight of cumene hydroperoxide, and the resulting products retard further thermal decomposition at 90 °C. quite strongly. The shortstop 2,4-dinitrochlorobenzene does not react with cumene hydroperoxide and would seem to act merely as a powerful retarder for the decomposition at the higher temperature. The effect of other related compounds on the decomposition of cumene hydroperoxide in styrene was less marked and agrees with the relatively less effectiveness of these compounds as stoppers in emulsion copolymerization.

The rate of emulsion copolymerization of butadiene and styrene, with soap as emulsifier and potassium persulfate as catalyst, is extremely small at 50°C. The presence of very small amounts of high-molecular mercaptans promotes the copolymerization reaction. The promoting effect is at a maximum for primary, secondary, and tertiary dodecyl mercaptans and decreases for mercaptans of either higher or lower molecular weight. The promoting effect is independent within wide limits of the amount of mercaptan added after the minimum quantity has been exceeded. Mercaptans which are poor promoters may be so because they fail to bring about chain initiation or because they aid in chain termination. The low-molecular mercaptans which are poor promoters prevent the high-molecular mercaptans from exerting their good promoting effect when a mixture of both types of mercaptans is used. The mechanism of the promoting effect of mercaptans upon the emulsion copolymerization of butadiene (75 parts) and styrene (25 parts) or upon the polymerization of butadiene alone is not yet clear.

Crosslinking in the styrene–butadiene emulsion copolymerization (21 parts styrene:79 parts butadiene) prior to gelation has been studied by means of partial conversion number-average molecular weights at 5, 15, and 25°C. It is shown that the macromolecular population begins to diminish at progressively lower conversions as the reaction temperature is increased. This is attributed to the relative increase in crosslinking over propagation as the reaction temperature is increased and also to the decrease in mercaptan regulating index with increasing temperature.

水溶性N-メチロールアクリルアミドとの乳化共重合におけるアクリル酸エステルの挙動をメチル,エチル,ブチルの各エステルの場合について比較検討した。エタノール中における均一系共重合では各エステルとも良好な共重合性を示すが(メチルγ1=1.9±0.7,γ2=1.3±0.2;エチルγ1=γ2=1.4±0.2;ブチルγ1=O.61±0.17,γ2 0.87±0.05),5%単量体濃度程度の水系共重合において, メチロールアクリルアミド-アクリル酸メチル系では, その初期共重合体組成は均一系に比較して著しくメチロールアクリルアミド成分が減少することが認められた。そしてこの初期組成はほとんど単量体濃度,乳化剤の有無に関係せず,またエタノール等の重合体溶剤の添加により均一系の値に近づけることが出来るのでこれは生成エマルジョン重合体粒子に対する両単量体の拡散,吸着能の差に起因するものと思われる。一方30%濃度では単量体組成と初期共重合体組成との関係はメチルの場合は乳化剤,かきまぜの影響は少なく均一系の関係に近い。ブチルではかきまぜ,乳化剤,いずれの影響も極めて大きく,エチルではこの中間状態を保つ。この関係は各エステルの水溶性の差を主因として説明可能である。またエタノール等の添加剤はこの場合も各エマルジョンの組成的均一性を向上させることが認められた。

Benzoyl, anisoyl, veratroyl, p-bromobenzoyl, p-phenylbenzoyl, p-benzoylbenzoyl, p-methylsulfonylbenzoyl, p(N,N-dimethylsulfonamido)-benzoyl and -naphthoyl disulfides are promoters of the emulsion copolymerization of butadiene and styrene, but exhibit little effect on the polymer properties. Furoyl, phenyl, p-chlorophenyl and p-bromophenyl disulfides are neither promoters nor modifiers.

Semicontinuous emulsion copolymerization of butyl methacrylate and butyl acrylate with a feed of monomer emulsion has been investigated. The influence of polymerization variables on the rate of polymerization was studied by measuring the temperature changes in a thermally insulated reactor during the initial period of polymerization. Reaction conditions were found for the maximum polymerization rate, determined by the feeding rate of monomer emulsion. Die halbkontinuierliche Emulsionscopolymerisation von Butylmethacrylat und Butylacrylat wurde untersucht. Der Einflus der Reaktionsbedingungen auf die Polymerisationsgeschwindigkeit wurde durch Messung der Temperaturanderungen in einem thermisch isolierten Reaktor wahrend der Anfangsphase der Polymerisation verfolgt. Die Reaktionsbedingungen fur die groste Polymerisationsgeschwindigkeit bei gegebener Zulaufgeschwindigkeit der Monomeremulsion wurden so ermittelt.

n-Octyl mercaptan has been found to be a better modifier for emulsion copolymerization of butadiene and styrene at 110° than is either n-butyl mercaptan or n-dodecyl mercaptan. Physical test data on vulcanized copolymers modified with n-octyl mercaptan are presented.

Bekanntlich sind Latices, die durch Emulsionscopolymerisation von Acrylestern mit Acrylsaure hergestellt werden, haufig verdickbar, d. h. ihre Viskositat steigt nach Zusatz einer Base, z. B. NH3, stark an. Zwischen der Verdickbarkeit einer Dispersion und der Volumenveranderung der Latexteilchen bei NH3-Zusatz — gemessen mit Hilfe von Streulichtmessungen — besteht ein direkter Zusammenhang. Die Quellung ihrerseits ist von der Hydrophilie des Hauptmonomeren abhangig. Dies erklart die Abnahme der Verdickbarkeit von Acrylester/Acrylsaure-Copolymerisatdispersionen mit steigender Kettenlange der Alkoholkomponente im Acrylester. Latices prepared by emulsion copolymerization of acrylates with acrylic acid can often be thickened, i.e., their viscosity shows a pronounced increase when NH3 or a similar base is added. There is a direct relationship between the ability of a latex to thicken and the volume change of the latex particles — determined by light scattering measurements — when NH3 is added. The degree of swelling depends on the hydrophilic character of the predominant monomer. This explains the decrease in thickenability of acrylate/ acrylic acid copolymer latex with increasing chain length of the alcohol component of the ester.

Cobalt complex compounds exhibited varying degrees of activation and retardation in butadiene-styrene-soap emulsion polymerization systems at 20–50°C. An accompanying effect was the wasting of modifier, particularly by large concentrations of activator. The most active complexes for use with dodecyl mercaptan were those in which the cobalt was coordinated with two or more negative groups other than thiocyanate, and in which the neutral coordinated groups were not ethylenediamine.

Die Copolymerisation von Acrylnitril und α-Chloracrylsauremethylester in Emulsion wurde kinetisch untersucht. Umsatz, Grenzviskositat, spezifisches Gewicht, Zusammensetzung der Copolymeren und Induktionsperiode wurden bestimmt. Die Wahrscheinlichkeit fur die Verteilung von Acrylnitril- und α-Chloracrylsaremethylester-Kettensegmenten wurde in Abhangigkeit von der Zusammensetzung des Monomeren gemisches bestimmt. Es wurde gezeigt, das die aus den beiden Monomeren aufgebauten Makromolekule aus unregelmasig angeordneten, kurzen Sequenzen bestehen. Ferner wurde gezeigt, das der Umsatz der Quadratwurzel der α-Chloracrylsauremethylester-Konzentration direkt proportional ist. Die Induktionsperiode nimmt mit der Erhohung der α-Chloracrylsauremethylester-Konzentration ab. Der Umsatz hangt vom pH-Wert des Reaktionsmediums ab. Bei pH > 7 ist die Reaktionsgeschwindigkeit sehr niedrig. The kinetics of the emulsion copolymerization of acrylonitrile and methyl α-chloro-acrylate were studied. Conversion, intrinsic viscosity, density, differential composition of the products and induction period were determined. Probability functions for the distribution of acrylonitrile and methyl α-chloro-acrylate chain segments were calculated. Macromolecules from these two monomers were shown to consist of randomly arranged short chain segments. It was shown that the degree of conversion is directly proportional to the square root of the concentration of methyl α-chloro-acrylate. The induction period decreases as the methyl α-chloro-acrylate concentration increases. The degree of conversion depends on the pH of the reaction medium. At a pH > 7 the reaction is markedly restrained.

1. In the emulsion copolymerization of butadiene with alkyl vinyl ethers in an alkaline medium the specific action of carbon tetrachloride is suppressed and the process proceeds almost entirely by the free-radical mechanism. 2. Introduction of ether units greatly reduces the molecular weight of polybutadiene (from 108,000 to 3,000). 3. The introduction of up to 20% of ether units in the polybutadiene chain has little effect on its stability to frost (TV = − 84°). When there is a predominance of ether units (70%), the stability to frost is greatly reduced (TV = − 30°), though the chemical stability is increased.

アクリル酸エチルとアクリルアミドの乳化共重合における水溶性添加剤の影響を検討した。PVA,CMC等の保護コロイドを使用する場合,その初期重合体組成は水系重合の場合に近い。一般に高分子添加剤はエマルジョンの粘度を上昇させるが,単量体組成アクリルアミド10%付近で最も低粘度のエマルジョンがえられる。また添加剤量を必要以上多くすることは不必要なエマルジョン粘度の増大を来すことが認められた。高分子添加剤中とくにCMCは5%程度のエマルジョン濃度でも著しくnon-Newtonianの挙動を示し,FN=η′Gの関係式が適用可能である。凝析値は粘度の場合と同じく10%アクリルアミド付近に最大値があり,とくにCMCを使用すると他の2倍程度の値になる。添加剤量を多くすると凝析値の低下する例も見受けられた。また尿素等樹脂加工剤の添加は著しく凝析値を減少させることも認められた。

It was found that the induced decomposition of peroxy compounds could lead to faster rates of polymerization or practical rates of polymerization at lower temperatures. In Germany polymerization recipes were developed containing a peroxy compound in the oil phase, a reducer in the aqueous phase and a metal carrier. This idea was transferred to America after the war and became the basis of the present recipes used in the production of cold rubbers. As reducers the most commonly used appear to be digested d-glucose or an excess of ferrous iron but recently the polyamines and other amine compounds have been found to be quite effective. The mixture of amine and sugar was better than either alone. It has been shown that this mixture will function in the presence of reactive monomers such as acrylonitrile. The role of such reducers is of considerable interest so that further studies were undertaken. The results obtained may be illustrated by acetoin. As the amount of acetoin is increased in the recipe the amount of ferrous iron required for maximal conversion in a given time is decreased. This is because at higher than the optimal amounts, although the reaction rate is still increasing, the catalyst system is rapidly exhausted so that the reaction dies at a lower conversion. The data can be explained by assuming formation of free radicals by the induced decomposition of the peroxide either by the acetoin, the ferrous iron, or a complex between the iron and acetoin. This free radical then initiates polymerization. The acetoin free radical residue can induce the further decomposition of the peroxide or possibly can reduce ferric iron to ferrous. Other compounds yield similar results.

Preparation des copolymeres ayant quelques groupes acetylacetonates(I) fixes aux unites styrene par copolymerisation en emulsion. Le copolymere est reticule par chelation des groupes (I) par l'acetate de palladium

A “carboxylated polymer” is one which contains a minor proportion of monomer units which bear carboxylic-acid groups copolymerized with a major proportion of monomer units which do not bear carboxylic-acid groups. By “minor proportion” in this context is meant between zero and about 10% by weight; in many cases, the amount is less than 5% by weight. It is usually understood that the carboxylic-acid-bearing monomer units are copolymerized essentially at random with the other monomer units; thus, for instance, the term “carboxylated polymer” as commonly used excludes carboxyl-terminated polymers in which the carboxylic-acid groups are confined to the ends of the polymer chains.

This paper, based on a series of emulsion polymerization experiments and on the concept of the inherent law of discrete variables correlated function, introduces physical concepts into the Euclidean Space and sketches a mathematical model to substitute the Bernstein polynomial equation.

A computer model is developed to simulate the emulsion copolymerization of styrene/butadiene in perfectly stirred batch, semi-batch or continuous flow reactors. The model considers free radical initiation by a redox mechanism, micellar particle nucleation, radical concentration as -a function of particle size, radical entry rate and termination rate and diffusion controlled termination and propagation reactions. It predicts conversion, copolymer composition, particle number, number and mass average molecular masses and tri- and tetra-functional branch frequencies. A simple method of estimating the particle size distribution is included in the model. Heat balances over the reactor and cooling jacket are considered and proportional-integra control of the reactor temperature is simulated. The model is used to simulate SBR copolymerization and styrene homopolymerization experimental data from the literature. These simulations tested only certain parts of the model and it is concluded that a more complete verification of the model can only be achieved by running a series of designed experiments. Qualitatively, the molecular mass, particle size distribution and reactor temperature predictions appear to be reasonable. The lack of appropriate temperature dependent rate constants currently limits the molecular mass predictions to isothermal conditions. A comparison of semi-batch operating policies designed to control copolymer composition is presented to illustrate the potential application of the model. Thesis Master of Engineering (ME)

The Cycolac(R) brand of ABS thermoplastics is produced by Borg-Warner Chemicals from acrylonitrile, butadiene, and styrene monomers; hence, the abbreviation ABS. The first commercial products were introduced in 1954 and have evolved into a family of materials. A pattern of blending and alloying that had been established before Cycolac resins became part of the product line was continued when ABS became available as a blend component.

Self-optimization of chemical reactions enables faster optimization of reaction conditions or discovery of molecules with required target properties. The technology of self-optimization has been expanded to discovery of new process recipes for manufacture of complex functional products. A new machine-learning algorithm, specifically designed for multiobjective target optimization with an explicit aim to minimize the number of “expensive” experiments, guides the discovery process. This “black-box” approach assumes no a priori knowledge of chemical system and hence particularly suited to rapid development of processes to manufacture specialist low-volume, high-value products. The approach was demonstrated in discovery of process recipes for a semibatch emulsion copolymerization, targeting a specific particle size and full conversion.

A dynamic model was developed describing emulsion copolymerization of styrene and MMA within a batch/semibatch stirred tank reactor. This model includes the initiation, propagation, transfer and termination steps of the monomers styrene and MMA. It also includes the mass and energy balance equations for the polymeric radicals. Energy balance equations incorporate the heat of reaction, internal and external heat transfer effects, as well as heat losses. The resulting sets of (differential/algebraic) equations were solved for both species concentrations and temperature profiles as functions of time. Experiments were conducted in a laboratory reactor, instrumented with platinum resistance thermal transducers and gravimetric conversion measurement devices. Thermal measurements in conjunction with the energy equations helped estimate monomer conversions as a function of time. The kinetic model predictions of conversion compared well with inferential calorimetric measurements, which were validated using gravimetric data. The experiments were run at variable operational conditions in terms of feed rate, temperature and monomers feed ratio. The calorimetric model was used as a soft sensor for the prediction of the rate of reaction, conversion and molar mass.

The effect of several operation conditions (temperature, residence time, recycle ratio, initiator concentration and emulsifier concentration) on the performance of a continuous loop reactor during the redox initiated emulsion copolymerization of vinyl acetate and Veova 10 was investigated. The study was carried out under industrial-like conditions, namely, high solids content latexes (55wt%) and high conversions (~90%). Both polymerization mechanisms and practical issues such as production rate and product quality are discussed.