The redox initiator, cumene hydroperoxide/tetraethylenepentamine (CHPO/TEPA), was used to initiate the emulsion polymerizations of styrene and methyl methacrylate (MMA). The hydrophobic CHPO acting as oxidizer would interact with the hydrophilic TEPA employed as the reducer at the particle-water interface where the vinyl monomer is present. The kinetics of the styrene and MMA polymerizations were studied under a temperature range of 30–70 °C. The polymerization rate, the concentration of monomer in the particles, the average number of latex particles and the number of radicals per particle were investigated to evaluate the propagation rate constant during interval II of the polymerization. With increasing temperature, the number of latex particles increases while the monomer concentration in the particles slightly decreases. The observed number of radicals per particle, calculated from the number average volume of the particles and the relation between the entry rate coefficients of free radicals into the particles and the exit rate coefficients of free radicals from the particle, was found to be approximately 0.47 and 0.5 in case of styrene and MMA polymerization, respectively. The calculation shows that the propagation rate constant, k
 p = 6.84 × 107e−37.65/RT and k
 p = 3.4 × 107e−31.05/RT L/mol∙s for styrene and MMA polymerizations over the temperature range studied, respectively.

Kinetic study of styrene and methyl methacrylate emulsion polymerization induced by cumene hydroperoxide/tetraethylenepentamine

A practical methodology for the computer modeling of multicomponent chain-growth polymerizations, namely, free-radical and ionic systems, has been developed. This is an extension of a paper by Hamielec, MacGregor, and Penlidis (Multicomponent free-radical polymerization in batch, semi-batch and continuous reactors. Makromol. Chem., Macromol. Symp. 1987, 10/11, 521). The approach is general, providing a common model framework which is applicable to many multicomponent systems. Model calculations include conversion of the monomers, multivariable distributions of concentrations of monomers bound in the polymer chains and molecular weights, long- and short-chain branching frequencies, chain microstructure, and cross-linked gel content when applicable. Diffusion-controlled termination, propagation, and initiation reactions are accounted for using the free-volume theory. When necessary, chain-length-dependent diffusion-controlled termination may be employed. Various comonomer systems are used to illustrate the ...

Mathematical Modeling of Multicomponent Chain-Growth Polymerizations in Batch, Semibatch, and Continuous Reactors: A Review

Use of measurements for enforcing the necessary conditions of optimality in the presence of constraints and uncertainty

Mathematical modeling and computer simulator/database for emulsion polymerizations

I. INTRODUCTION Emulsion polymerization often has significant advantages over homogeneous bulk or solution polymerization. Aside from the obvious physical advantages when a polymer latex is the final product as in paints or other coatings, there are distinct processing advantages. For example, low viscosity and good temperature control can often be achieved in an emulsion polymerization when this is impossible in bulk. In addition, high molecular weight polymer can usually be produced at much higher reaction rates in an emulsion polymerization reactor than in a bulk polymerization. For these and other reasons, emulsion polymerization has become a multibillion dollar/year processing operation in terms of sales in the United States alone.

On the Mathematical Modeling of Emulsion Polymerization Reactors

In emulsion polymerization, the Smith and Ewart theory gives about two or three times the number of polymer particles obtained by experiment. In this paper, a reaction model is proposed which, from the standpoint of reactor design, can give an adequate explanation of the whole course of an emulsion polymerization of monomer highly insoluble in water. Among other things, the generating process of polymer particles is examined in detail. It is demonstrated experimentally that a new parameter proposed here, which represents the degree of difficulty of monomer initiation in micelles, is indispensable in explaining that process. Also confirmed is that monomer initiation takes place more easily in polymer particles than in micelles. According to the new model, the progress of polymerization, i.e., monomer conversion, the number of the polymer particles, and properties of polymer thus produced can be estimated with satisfactory accuracy. Furthermore, approximate equations are derived for easier estimation.

Rate of emulsion polymerization of styrene

The kinetics of continuous emulsion polymerization of styrene were studied theoretically on the basis of the authors' batch reaction model, and a new reaction model was proposed for continuous operation. The validity of the model was tested by experiments conducted with stirred tank reactors in series. The characteristics of the first reactor used to generate polymer particles were studied in particular detail. It was found that there was an optimum residence time for the first reactor, the value of which was quantitatively predictable from the operating variables. The most suitable combinations of several types of reactors for continuous emulsion polymerization are also discussed.

Continuous flow operation in emulsion polymerization of styrene

Thirty-four Holstein dry cows and 16 lactating cows were used in balance trials to identify the effects of feeding and animal performance on nitrogen (N), phosphorus (P) and potassium (K) excretion by dairy cows, and to develop prediction models for these excreta. Orchard grass silage, corn silage, alfalfa silage or timothy hay were offered to dry cows. Orchard grass silage or alfalfa silage, and concentrates were offered to lactating cows. In the statistical analysis, the independent variables were bodyweight (kg), dry matter (DM) intake (kg/day), milk yield (for lactating cows only, kg/day), water intake (free water plus water in feed, kg/day), intake (g/day) of N, P and K and dietary contents (% of DM) of crude protein, P and K. The dependent variables were N, P and K excretion (g/day) in feces and urine. In both dry and lactating cows, intake of N, P and K had large effects on corresponding excretion. The results indicated that a decrease in the intake of N, P and K could decrease the corresponding excretion. Further research by path analysis showed that K intake positively affected urinary N excretion in dry cows indirectly, through water intake and urine volume.

Effects of feeding and animal performance on nitrogen, phosphorus and potassium excretion by Holstein cows

本研究の目的は，乳牛のリン排泄量を予測するモデルを開発し，そのモデルを用いてシミュレーションを行い，乳牛によるリン排泄量抑制の手段を検討することであった．ホルスタイン種雌牛を用いた日米のリン出納実験のデータを用いてモデルの妥当性を検証した．その結果，日本のデータでは本モデルは予測値と実測値がよく一致したが，アメリカのデータでは過大に予測される傾向のあることが示唆された．このような結果が得られたのは，本モデルが日本飼養標準（1999）に基づいて作成されており，日本国内の飼養条件のみが考慮されているためと推察された．飼料中リン濃度（DPC ; g/乾物kg）と305日間にわたる泌乳期間中の305日乳量（TMY ; kg）をそれぞれ独立に変化させ，305日間の泌乳期間中のリン排泄量（TPexc ; kg）と，総リン摂取量に対する総リン排泄量の比（I1）および305日乳中のリン量に対する総リン排泄量の比（I2）の2種の環境負荷指標に対するこれらの要因の影響を調べた．その結果，DPCの低下はTPexcとI1およびI2を低下させ，TMYの増加はTPexcを増加させるが，I1およびI2のいずれもを低下させることが示された．

Hideki Kojima

Papers

Rate of emulsion polymerization of styrene

Continuous flow operation in emulsion polymerization of styrene

Effects of feeding and animal performance on nitrogen, phosphorus and potassium excretion by Holstein cows

Development and Simulation of a Model for Predicting Phosphorus Excretion in Dairy Cows