Condensation polymers description

Section 5.5 should be consulted for a general description of this process, which applies only to the production of condensation polymers. 

The book begins with terms commonly used in polymer chemistry and biochemistry with respect to various substances, such as homopolymers, copolymers, condensation polymers, addition polymers, proteins, nucleic acids, and polysaccharides (Chapter 1), followed by descriptions of the methods used to create these substances (Chapter 2). On the basis of classroom experience, Chapter 2 is a welcome introduction to students who have never been exposed to the basic methods of polymer and biopolymer syntheses. The first two chapters together comprise the essential background materials for this book. 

Data descriptions for the reaction pyrograms and the MS data of the major peaks on the pyrograms for 33 condensation polymer samples... 

The preceding equations will, of course, be somewhat in error owing to the neglect of intramolecular condensations. Very large species will be suppressed relatively more on this account. All conceivable errors can do no more, however, than to effect a distortion of the quantitative features of the predictions, which will be small in comparison with the vast difference between the branched polymer distribution and that usually prevailing in linear polymers. From this point of view, the statistical theory given offers a useful description of the state of affairs. 

Hoftyzer and van Krevelen [100] investigated the combination of mass transfer together with chemical reactions in polycondensation, and deduced the ratedetermining factors from the description of gas absorption processes. They proposed three possible cases for poly condensation reactions, i.e. (1) the polycondensation takes place in the bulk of the polymer melt and the volatile compound produced has to be removed by a physical desorption process, (2) the polycondensation takes place exclusively in the vicinity of the interface at a rate determined by both reaction and diffusion, and (3) the reaction zone is located close to the interface and mass transport of the reactants to this zone is the rate-determining step. 

Fig. 3. Schematic description of self-condensing vinyl polymerization used for the synthesis of of hyperbranched polymers based on vinyl monomers as presented by Frechet [52] -(represents a reactive site which can initiate polymerization)...

A polyelectrolyte solution contains the salt of a polyion, a polymer comprised of repeating ionized units. In dilute solutions, a substantial fraction of sodium ions are bound to polyacrylate at concentrations where sodium acetate exhibits only dissoci-atedions. Thus counterion binding plays a central role in polyelectrolyte solutions [1], Close approach of counterions to polyions results in mutual perturbation of the hydration layers and the description of the electrical potential around polyions is different to both the Debye-Huckel treatment for soluble ions and the Gouy-Chapman model for a surface charge distribution, with Manning condensation of ions around the polyelectrolyte. 

Due to the fact that industrial composites are made up of combinations of metals, polymers, and ceramics, the kinetic processes involved in the formation, transformation, and degradation of composites are often the same as those of the individual components. Most of the processes we have described to this point have involved condensed phases—liquids or solids—but there are two gas-phase processes, widely utilized for composite formation, that require some individualized attention. Chemical vapor deposition (CVD) and chemical vapor infiltration (CVI) involve the reaction of gas phase species with a solid substrate to form a heterogeneous, solid-phase composite. Because this discussion must necessarily involve some of the concepts of transport phenomena, namely diffusion, you may wish to refresh your memory from your transport course, or refer to the specific topics in Chapter 4 as they come up in the course of this description. 

According to descriptions published by the Thiokol Chemical Corporation [9] and Gobel [10] liquid thiokol is obtained in the following way ethylene chloro-hydrin is condensed into dichlorodiethylformal (I) which is then treated with sodium polysulphide to form the polymer (II) ... 

Figure 3. Effect of EME 58 (58 wt% mercaptoester units co-polymer) coupling agent concentration on the peel strength of flexible epoxy (amine-cured)/AD = acetone-degreased steel test panels following (a) I day and (b) 3 day exposure to 57°C condensing humidity. See Appendix 4 for epoxy resin and cure description.

See under Siloxanes in article on Silanes in this Vol for the definition and a brief description of the basic molecular structure. The name silicone was created by F.S, Kipping as an analogy to ketones. However, his silicane-diols , (Aryl)2Si(OH)2 could not be dehydrated to silicones but always condensed to higher mw Si—0—Si compds. These structures were then (early 1900s) referred to as silicones. In time the name has come to represent any organo-silicon oxide polymer, such as polydimethy-siloxane (see below) ... 

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