Polymerization processes feed preparation

Of course, the preparation of a quality microcapsule is not only determined by a single factor but the collective interactions of a large number of the factors. Besides what described above, other factors like reactant feeding speed, polymerization catalyst, etc. can also affect the polymerization process, which consequently affect the properties of the microcapsule. 

Mass Polymerization Process. In the mass (114-122) ABS process, the polymerization is conducted in a monomer medium rather than in water, usually employing a series of two or more continuous reactors. The rubber used in this process is most commonly a solution polymerized linear polybutadiene (or copol5nner containing sytrene), although some mass processes utilize emulsion-polymerized ABS with a high rubber content for the rubber component (123). If a linear rubber is used, a solution of the rubber in the monomers is prepared for feeding to the reactor system. If emulsion ABS is used as the source of rubber, a dispersion of the ABS in the monomers is usually prepared after the water has been removed from the ABS latex. 

Melt-Phase Polymerization. Commercially pen is produced from 2,6-NDC (abbreviated to NDC in the rest of this article) in a process analogous to producing PET from DMT. The reactivity of NDC in a PEN pol5unerization process is similar to that of DMT in a PET polymerization process and similar catalyst and conditions can be used. Because of this, PEN preparation can be typically accomplished in existing DMT-based polymerization facilities with only minor modification. This modification is generally limited to the NDC feed system and changes required to handle the physical property differences of NDC vs DMT and of PEN vs PET. 

In general, the requirements for purity of the reagents, solvents, and monomers are much higher in anionic polymerization than in free-radical polymerization. Necessary distillations and/or adsorption towers, often with activated aluminum, increase the costs for feed preparation compared to free-radical processes. 

The emulsion polymerization process (batch or continuous) is widely used for producing ABS because various grades of ABS resins can be manufactured. In a continuous process, two to six reactors are used in series with rubber latex feed added either to the first reactor or the first two reactors. In a typical ABS emulsion process, the styrene/acrylonitrile copolymer (SAN) and polybutadiene (PBL) are separately prepared by emulsion pro-... 

Feed Preparation. Although propane, butane, etc., may be decomposed or dehydrogenated to produce propylene and butenes (pages 644 to 652), this method is not followed except in thermal polymerization processes... 

To prepare water-soluble polymers employing CCT, it is necessary to modify the polymerization conditions.312 439 Use of a standard batch reaction leads to hydrolysis of catalyst, changing the catalyst level over the course of the polymerization, yielding a mixture of products and poor control of the reaction. A feed or starved-feed process that adds catalyst over the course of the reaction maintains a constant catalyst level and high conversion. The approach can be applied to a range of monomers such as methacrylic acid, 2-aminoethyl methacrylate hydrochloride, 2-hy-droxyethyl methacrylate, 2-methacryloxyethyl phos-phoryl choline, glycerol monomethyl methacrylate, and 3- O-methacryloyl-1,2 5,6-di- O-isopropylidene-D-glucofuranose. 

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