Polymerization reactions overview

This section introduces simple polymer reaction chemistry used to produce many commodity polymers. Understanding this simplified approach to the chemistry of polymer production Is Important In troubleshooting many extrusion processes, especially those that are producing unwanted degradation products that contaminate the discharge resin. There are two general types of polymer production processes 1) step or condensation reactions, and 2) addition or vinyl polymerization reactions. An overview of the reaction mechanisms wifi be presented in the next sections. 

This discussion is not intended to be an exhaustive review of the wood-polymer literature, but rather an overview of the processing procedures used today. In general, the free radicals used for the polymerization reaction come from two sources, temperature sensitive catalysts and Cobalt-60 gamma radiation. In each case a free radical is generated by the process, but from that point the vinyl polymerization mechanism is the same. Each... 

In this account, an overview of the methods employed for the synthesis of conjugated dienes and polyenes is presented. Dienes and polyenes with isolated double bonds are excluded, as they are accessed through methods usually employed for alkene synthesis. Oligomerizations and polymerization reactions leading to polyenes are also not covered. Synthesis of 1,2-dienes, i.e. allenes, is excluded from the purview as there is a volume in the present series devoted to this functional group. Synthesis of heterodienes, conjugated enol ethers, [n]-annulenes and related compounds are also not covered here. However, enynes, dienynes and enediynes syntheses have been included in a few cases in view of their emerging importance. 

This section is concerned with polymers derived from open-chain phosphazenes, phospha(thia)zenes and related cross-linked materials. Cyclolinear and cyclomatrix materials as well as carbon-chain polymers with cyclophasphazene substituents are covered in Section 3. General and specific reviews have appeared including an overview of recent development in inorganic polymers including poly(phosphazenes), a comprehensive survey of hybrid siloxane-phosphazene systems, water-soluble phosphazenes and related hydrogels, a brief survey of polymerization reactions and mechanisms, and sulfur containing poly(phosphazenes). ... 

There are several formulation components that can be present in an emulsion polymer (latex) formulation, which can be added before, during, or after the polymerization reaction. This section is intended to provide the reader with an overview on the role of each component, as well as their in impact the process and/or the product. 

Specific examples of single-phase turbulent reacting flows in a tubular jet reactor are discussed in Section 9.10.4.1. We select representative industrial problems of engineering interest for the two fundamental classes of polymerization reactions, namely addition and condensation polymerization. For each example, we present a general overview of the problem and detailed reacting flow analyses, followed by useful process design and operational information. 

For the development of sustainable polymer processes, ultrasound is an interesting technology, as it allows for polymerizations without the use of initiator. The radicals are generated in situ by cavitation events [116, 117], which make possible a dean and intrinsically safe polymerization reaction. As a result of the high strain rates outside the bubble, cavitation can also induce chain scission [118,119], which provides an additional means to control the molecular weight of the polymer produced. In Sections 21.3.1 and 21.3.2 the physical background of ultrasound-induced cavitation and radical formation will be described. Subsequently (see Section 21.3.3), an overview of the several types of ultrasound-induced polymerizations will be given, namely bulk, predpitation, and emulsion polymerization. 

The foregoing overview of polymer characteristics leads up to a consideration of which of these are important candidates for online monitoring. There is a long history of attempts at online monitoring using GPC, in order to obtain MWD at discrete intervals during polymerization reactions. 

Giudici R. Polymerization reaction engineering a personal overview of the state-of-art. Lat Am Appl Res 2000 30 351-356. 

Cerium(IV) ions are widely used as initiators for radical polymerizations of vinyl monomers (acrylamide, acrylonitrile, methyl methacrylate, vinyl acetate,. ..). In order to act as an initiator, a reductant has to be added to the solutions containing the monomer and a cerium(IV) salt. Free radicals are produced by the oxidation of the reductant by cerium(IV) and these free radicals can initiate the polymerization reaction. Table 3 gives an overview of the different... 

Overview of radical polymerization reactions initiated by cerium(TV)... 

The field of step-growth polymers encompasses many polymer structures and polymerization reaction types. This chapter attempts to cover topics in step-growth polymerization outside of the areas reviewed in the other introductory chapters in this book, i.e., poly(aryl ethers), dendritic polymers, high-temperature polymers and transition-metal catalyzed polymerizations. Polyamides, polyesters, polycarbonates, poly(phenylene sulfides) and other important polymer systems are addressed. The chapter is not a comprehensive review but rather an overview of some of the more interesting recent research results reported for these step-growth polymers, including new polymerization chemistries and mechanistic studies. 

In the last 50 years, scientists have developed novel polymerization approaches, leading to new polymeric materials and applications, with the pace of new discoveries growing. This chapter provides an overview of this body of research, focusing on reactions involving covalent modification of double bonds to prepare monomers (particularly on the formation of polyols for employment as monomers for polyurethane synthesis), direct polymerization reactions between polyunsaturated acyl groups (eg, Diels-Alder, free radical, metathesis. 

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