Polymerization continued continuous

We shall consider these points below. The mechanism for cationic polymerization continues to include initiation, propagation, transfer, and termination steps, and the rate of polymerization and the kinetic chain length are the principal quantities of interest. 

A unique feature of in situ encapsulation technology is that polymerization occurs ia the aqueous phase thereby produciag a condensation product that deposits on the surface of the dispersed core material where polymerization continues. This ultimately produces a water-iasoluble, highly cross-linked polymer capsule shell. The polymerization chemistry occurs entirely on the aqueous phase side of the iaterface, so reactive agents do not have to be dissolved ia the core material. The process has been commercialized and produces a range of commercial capsules. 

Equation 20 is the rate-controlling step. The reaction rate of the hydrophobes decreases in the order primary alcohols > phenols > carboxylic acids (84). With alkylphenols and carboxylates, buildup of polyadducts begins after the starting material has been completely converted to the monoadduct, reflecting the increased acid strengths of these hydrophobes over the alcohols. Polymerization continues until all ethylene oxide has reacted. Beyond formation of the monoadduct, reactivity is essentially independent of chain length. The effectiveness of ethoxylation catalysts increases with base strength. In practice, ratios of 0.005—0.05 1 mol of NaOH, KOH, or NaOCH to alcohol are frequendy used. 

The polymerization continues (as in the last three steps shown above) until termination occurs and the hydrocarbon is desorbed ... 

Analysis of mixture models, established techniques, 61 Analysis of styrene suspension polymerization continuous models, 210-211 efficiency, 211,212f,213 free volume theory, 215,217 initiator conversion vs. 

Copolymerisation is also possible (Fig. 4). Dimethyldisilane reacts with diphenylsilane with formation of a copolymer with the composition H[(MeSiHx)(PhSiHy)]nH. This copolymer is a viscous liquid and is spinnable. By heating to 180° C the polymerization continues and a solid results [23]. The presence of branched structures, which were not found with the polymerization of monosilanes, the very rapid polymerization rate achievable, and the observable SiSi cleavage points to another mechanism, as was postulated for monosilanes. 

In the case of ethylene the hydride formed realkylates rapidly and polymerization continues ... 

Manufacturing Processes. The three manufacturing processes already mentioned (continuous mass polymerization, batch suspension and emulsion polymerization) continued to compete with each other after 1945. Whereas the third one gradually decreased in importance, the other two were given preference in... 

J. Alvarez, R. Suarez, and A. Sanchez. Nonlinear decoupling control of free radical polymerization continuous stirred tank reactors. Chem. Enq. Sci., 45 3341-3354, 1990. 

The monomer used in the Mo catalyst attempts was basketene. Reactions were run at room temperature. After 2 hours, the temperature was raised to 70-80 °C. In all cases, the monomer remained unreacted, while the catalyst decomposed. Survey of conditions for successful polymerization continues. 

Figure 4. Rate of polymerization (continuous curve) and rate of shrinkage (dotted curve) for TEGDA containing 3.4 w% DMPA and 0.3 w% TEGDB. Temperature 20°C. Light intensity 0.2 mW.cm . ...

The maximum extent of double bond conversion in TEGDA as measured with DSC increases not only with temperature but also with light intensity. Mechanical measurements show, however, that the intensity dependence vanishes when equal doses are applied. This means that at low intensities the polymerization continues for a considerable time at a rate which is imperceptible with DSC. 

When a monomer such as acrylonitrile is polymerized in a poor solvent, macroradicals precipitate as they are formed. Since these are living polymers, polymerization continues as more acrylonitrile diffuses into the precipitated particles. This heterogeneous solution polymerization has been called precipitation polymerization. 

Polymerization continues in stage II, and monomer continues to be supplied to the particles by the droplets in the aqueous phase. These droplets disappear when about 30% of the monomers has been converted to polymers. Polymerization continues in stage III after about 60% conversion, but all monomers must now be supplied to the macroradicals by a diffusion process in the micelles. 

The particle number remains the same in interval III as in interval II, but the monomer concentration decreases with time, since monomer droplets are no longer present. The decrease in 4>m is slower with the more water-soluble monomers as the monomer in solution acts as a reservoir. The presence of a gel effect continues in interval IE. The quantitative interplay of a decreasing monomer concentration with the gel effect determines the exact behavior observed in this interval (GF or H). Polymerization continues at a steadily decreasing rate as the monomer concentration in the polymer particles decreases. Final conversions of essentially 100% are usually achieved. The final polymer particles, spherical in shape, usually have diameters of 50-300 nm, which places them intermediate in size between the initial micelles and monomer droplets. 

The propagation kinetic constant remains relatively constant at low to moderate conversions where diffusion of the smaller monomer molecules is unhindered. As the critical free volume for the diffusion control of propagation is reached, kp begins to decrease. Diffusion of monomer molecules is now the rate controlling step for propagation. As polymerization continues and conversion increases (free volume decreases), the diffusion of the monomer and kp drastically decrease. 

After the exposure to UV light, cationic polymerization continues for a long time. 

Deionized water (720 g), sodium lauryl sulfate (4.3 g), dioctanoyl peroxide (40 g), and acetone (133 g) were emulsified using an ultrasonic probe for 10 minutes. The step 1 polystyrene seed (48.0 g seed, 578 g latex) was added to the emulsion together with lauryl sulfate (0.8 g) and acetone (29.6 g). The mixture was transferred to a flask and left to agitate at approximately 25°C for 48 hours. Acetone was then removed and the solution added to a 5-liter double-walled glass reactor. The temperature was increased to 40°C while styrene (336 g) and divinyl benzene (0.88 g) were added drop-wise over approximately 60 minutes. After 4 hours the mixture was treated with deionized water (1200 g), potassium iodide (1.28 g), and polyvinyl pyrrolidone (18.48 g) with the temperature increased to 70°C. The polymerization continued for 6 hours at 70°C and 1 hour at 90°C. Styrene-based oligomer particles with a diameter of 1.7 pm and with a narrow size distribution were obtained. 

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