Propagation of polymerization

Other reasons for a wide propagation of polymerization in water include (1) reduction of energy consumed to separate the initial monomer in crystal form (acrylamide is produced and used in the aqueous solution form), which, in addition, is associated with the probability of its spontaneous polymerization, and (2) recovery of the organic solvents, which results in less environmental pollution and the elimination of the stage of solution of polymer reagents used, as a rule, in the form of the aqueous solutions. 

Projections, linearly independent, 293 Propagation, of polymerization, 158 Propane, hydrate, 10, 33, 43, 46, 47 hydrate thermodynamic data and lattice constants, 8 + iodoform system, 99 Langmuir constant, 47 water-hydrogen sulfide ternary system, 53... 

The charged end of a polymer and its counter-ion may recombine and form a stable covalent bond thus terminating the propagation of polymerization. Such a termination is frequently observed in carbonium ion polymerizations. For example, polymerization of a vinyl monomer if initiated by hydrochloric acid produces a carbonium ion and a chlorine-counter-ion. These two ions recombine readily forming a stable covalent C-Cl bond which does not propagate further the polymerization and forms, therefore, the dead end of a polymeric molecule. Actually, the recombination of carbonium ion with Cl- ion is such a rapid reaction that usually it follows immediately the formation of the relevant carbonium ion. This prevents the formation of a polymeric molecule and gives instead an addition product of HC1 to the reactive C=C double bond. A polymeric product can be obtained if the ions recombination is slowed down by sufficiently powerful solvation. For example, a solution of styrene in nitromethane, but not in a hydrocarbon, can be polymerized by HC1 (2), since the recombination of the solvated ions is sufficiently slow to permit the formation of a polymer. 

A quantitative description of the solidification process of a reactive mixture is based on the kinetic equations for that define the reaction parameters. One of these parameters is the "calorimetric" degree of conversion, which describes the linear propagation of polymeric chains ... 

Once induced, additional energy is not necessary for propagation of polymerization due to highly exothermic nature of the polymerization. Therefore, many polymers can be quickly synthesized by using FP characterized by the localized reaction zone and the fast increasing temperature. 

Scheme 10.2 Propagation of polymerization of acetylenes by metal carbene and metallacylobutene carriers.

This chapter discusses propagation of polymerization waves. In a polymerization wave, a spatially localized reaction zone, in which the polymerization reactions occur, propagates into initial reactants (the monomer) leaving the reaction product (the polymer) in its wake. Two types of polymerization waves, thermal and isothermal, have been observed experimentally, and the mechanism of wave propagation for each is markedly different. Thermal polymeriza-... 

Studies of ionic reactions were extended to processes other than propagation of polymerization. A variety of protonation processes, electron transfers, dimerizations, cis-trans isomerizations, etc., were investigated with emphasis on the role of different types of ionic species on the course of these reactions. The results of these studies were reviewed in two volumes entitled "Ions and Ion-Pairs in Organic Reactions" edited by Professor Szwarc, who contributed four chapters to this extensive compilation. These books were published by Wiley in 1970 (volume I) and 1972 (volume II). 

For initiation in the aqueous phase, the principal function of the emulsifier is to stabilize the oligomeric radicals as they precipitate from the aqueous phase. Therefore, the initiation and propagation of polymerization in the aqueous phase follows the general kinetic scheme for mass, solution, and suspension pol3nnerization the expression for the number-average degree of polymerization is 5 ... 

In contrast to this proposal, MacDonald et al. [64] su ested that the chain propagation of polymerization was a slow step, while Gross et al. [65] found that the monomer conversion followed first- order law and was independent of both the type (water, butanol and butyl amine) and concentration of the nucleophile. Yet another group suggested a complex mechanism of polymerization involving ring-opening and linear condensation polymerization [66]. 

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