Polymer reactions, defined

The simplest scenario to simulate is a homopolymerization during which the monomer concentration is held constant. We assume a constant reaction volume in order to simplify the system of equations. Conversion of monomer to polymer, Xp defined as the mass ratio of polymer to free monomer, is used as an independent variable. Use of this variable simplifies the model by combining several variables, such as catalyst load, turnover frequency, and degradation rate, into a single value. Also, by using conversion instead of time as an independent variable, the model only requires three dimensionless kinetics parameters. 

This document presents clear concepts and definitions of general and specific terms relating to reactions of polymers and functional polymers. The document is divided into three seetions. In Seetion 1, terms relating to reaetions of polymers are defined. Names of individual ehemical reaetions (e.g., chloromethylation) are omitted from this doeument, even in eases where the reaetions are important in the field of polymer reaetions, beeause sueh names are usually already in widespread use and are well defined in organie... 

The resistance to fluid flow is a measure of the physical structure of the foam. In order to control the flow through a foam, ceU size, degree of reticulation, density, and other physical factors must be controlled. The control of these physical factors, however, is achieved through the chemistry and the process by which the foam is made. The strength of the bulk polymer is measured by the tensile test described above, but it is clear that the tensile strengths of the individual bars and struts that form the boundaries of an individual cell determine, in part, the qualities of the cells that develop. A highly branched or cross-linked polymer molecule will possess certain tensile and elongation properties that define the cells. The process is also a critical part of the fluid flow formula, mostly due to kinetic factors. As discussed above, the addition of a polyol and/or water to a prepolymer initiates reactions that produce CO2 and cause a mass to polymerize. The juxtaposition of these two reactions defines the quality of the foam produced. Temperature is the primary factor that controls these reactions. Another factor is the emulsification of the prepolymer or isocyanate phase with the polyol or water. 

One of the most important technical reactions of alkenes is their conversion to higher-molecular-weight compounds or polymers (Table 10-4). A polymer is defined as a long-chain molecule with recurring structural units. Thus polymerization of propene gives a long-chain hydrocarbon with recurring... 

The growth of polymer chains is limited by termination and transfer. Therefore, these reactions define the total number of polymer chains in nonliving systems. The rate of termination is usually independent of monomer concentration, and is first order in active species since termination generally occurs by reaction with counteranion [Eq. (109)]. 

The dissociation constant, Kj, for this reaction, defines the monomer concentrations at which the polymerization reaction will take place, because the concentration of polymers of length n + 1 will be essentially equal to that for polymers of length n. Thus,... 

The term "condensation polymers" was introduced by W. H. Carothers in his early work on the preparation of polyesters and polyamides to distinguish this class of polymers from vinyl polymers made by addition reactions. Condensation polymers were defined as polymeric molecules that may be converted by hydrolysis, or its equivalent, into monomers that differ from the structural units by one molecule of H2O, HCl, NHj, etc. This broad definition includes many polymers made by ring-opening or addition reactions, for example, lactone and lactam polymers, polyurethanes, polyureas, polyimides, and polyhydrazides, as well as polymers made by true condensation reactions. 

A telechelic polymer is defined as a relatively low-molar-mass spedes (M < 20,000), with functional end groups that can be used for further reaction to synthesize block copolymers or for network formation. Cationic polymerization methods can be used to prepare these fimctionalized polymers using the initiator-transfer, or Inifer, technique perfected by Kennedy. If the initiating catalyst-cocatalyst system is prepared from a Lewis acid and an alkyl or aryl halide, i.e.. 

A semi-IPN is a material containing one linear polymer and one crosslinked polymer.I in this case, an inorganic network was formed throughout a polyimide matrix via a sol-gel reaction of an alkoxysilane dye (ASD). Thus, this type of polymer is defined as... 

Living polymerizations do not have either transfer or termination reactions, that is, the active chain carrier remains bound to an individual polymer chain up to the yield determined by the monomer-polymer equilibrium. The ionic ends of the living polymer can thus be used to produce block polymers of defined structure. This ability, however, depends on the polarity of the growing macroanion and the monomer to be added on. To a first approximation, the polarity can be described in terms of what is known as the e values of the two monomers. Electron-poor monomers have high e values and electron-rich monomers have strongly negative e values (see also Section 22.2.5). For example, the poly(methyl methacrylic anion) (monomer e = 0.40) starts the polymerization of acrylonitrile e = 1.20), but not that of styrene e = —O.SO). Conversely, however, the poly(styryl anion) can start the polymerization of methyl methacrylate. 

Optimal conditions of the synthesis of these polymers were defined 1,2-dichlorrthane was a dissolvent, the temperature of the reaction was 295K, the time of eanying out was 60 minutes, consentration was 0,5m/l, thriethylamin was used as a eatalist. PEEKs were obtained with a quantitative output and high indices of the given viscidity (n =1,2-2,5 d/g). 

As the product of the reaction is a mixture of polymer compounds of different chain lengths, the product quality is a strong function of weight distribution of these polymer compounds. Define W, as the weight fraction of the polymer compound Pr (of chain length r) in the product. If is the molecular weight of monomer M, we can write W, as... 

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