Weights kinetics and molecular

The preceding discussions of the kinetics and molecular weight distributions in the step-growth polymerization of AB monomers are clearly exemplified by the esterification reactions of such monomers as glycolic acid or co-hydroxydecanoic acid. Therefore one method for polyester synthesis is the following ... 

Challa, G., The formation of polyethylene terephthalate by ester interchange. Equilibria kinetics and molecular weight distribution, Ph.D. Thesis, University of Amsterdam, 1959. 

Equations (17), (21), (32), (33) and those of Table 1 completely determine the instantaneous polymerization kinetics and molecular weight averages. Simple relationships are available... 

The above model not only predicts successfully the observed kinetics and molecular weight dependencies of the VCl3/Al(i—Bu)3/4-methyl-l-pentene system but also appears to have fairly general application to many other Ziegler-Natta systems. 

Nakaoki, T., Kalra, B., Kumar, A., Gross, R.A., Kirk, O., and Christensen, M. (2002) Candida antarctica lipase B catalyzed polymerization of lactones Effect of immobilization matrix on polymerization kinetics and molecular weight. Abstracts of Papers of the Am. Chem. Soc., 224, U473. 

Peculiarly there is no relationship between the concentration of the growing species and the amount of p-ClC6H4N PFfl used. This is probably due to the irreproduci-bility of the thermal decomposition of the diazonium salt. In experiments 1-3 (cf. Table 8.3) the amount of liberated PF5 was apparently different, although the amount of pClC6H4N+PF was kept constant. This observation weakens the authors29 earlier statement concerning the effect of initiator concentration (expressed in terms of precursor concentration) on the polymerization kinetics and molecular weights. 

The kinetics and molecular weight distribution in the hydrolytic process were studied and described in detail by Reimschuessel27,28). The molecular weights and the equilibrium conversion decrease with an increase of temperature but this influence is not very important due to the narrow temperature range (220-260 °C) applied in practice. Polymerization is usually carried out with 1-5 % initiator (H20, aminocaproic acid, 6,6 salt) for a few hours. The process involves three steps l,29). In the first one 90% polymer with molecular weight Mn = 8000 to 14000 is formed. The second step consists of condensation of these chains into polymers with Mn = 18 000 to... 

EXAMPLES OF SEVERAL FREE RADICAL (CO)POLYMERIZATION SCHEMES AND THE RESULTING KINETIC AND MOLECULAR WEIGHT DEVELOPMENT EQUATIONS... 

Nguyen TQ, Kausch HH (1988) Chain scission in transient extensional flow kinetics and molecular-weight dependence. J Nonnewton Fluid 30 125-140... 

Nitroxide-mediated miniemulsion polymerization reactions can also be performed successfully in a tubular reactor [80]. The demonstrated case used a tubular reactor with an i.d. of 2 mm and a length of 170 m. Samples prepared in the tubular reactor are comparable to those made in a batch reactor in terms of kinetics and molecular weight characteristics. 

Vinyl Ethers.—Two studies on the polymerization of isobutyl vinyl ether highlight the large differences possible in mechanism when different initiators are employed. Thus, with iodine," propagation from free ions and ion-pairs described the kinetics and molecular weights adequately, while with trifluoroacetic acid the system appeared to be pseudocationic with a monomer-solvated covalent ester as the predominant chain-carrier. 

The polymerization of styrene from benzyl chloride-POSS was run in 50% p-dimethoxybenzene at 120 using a copper chloride / N,N,N ,N N -penta-methyldiethylenetriamine (PMDETA) catalyst system. The kinetic and molecular weight plots are illustrated in Figures 5 and 6 respectively. They show that the concentration of active species was conserved throughout the polymerization in the absence of transfer reactions, and that the condition of fast initiation is not hampered by the inorganic fragment. 

Kinetics and molecular weight evolution during controlled radical polymerization. Macromol Chem Phys 2002 203 2029-2041. Wiley-VCH Verlag GmbH Co. KGaA. Reproduced with permission. 

Direct comparison of kinetic and molecular weight from the continuous nonchromatographic and SEC approaches showed that addition of multidetector SEC enhances data gathering power of ACOMP by bringing valuable complementary information. 

Free Radical Polymerization Kinetics and Molecular Weight Considerations... 

Wu JY, Shan GR. Kinetic and molecular weight control for methylmethacrylate semi-batch polymerization. 1. Modelling. J Appl Polym Sci 2006 100 2838-2846. 

The aim of this review is to summarize and discuss the kinetic data of the emulsion polymerization and copolymeiization of vinyl chloride. The current understanding of the kinetics of free-radical polymerization of conventional monomer is briefly described and kinetic data of radical polymerization and copolymerization of vinyl chloride in the presence of hydrophobic and hydrophilic additives are summarized. Efiects of the initiator type and concentration, the reaction conditions and the type of diluent are evaluated. Variation of kinetic and molecular weight parameters in the heterogeneous polymerizations with emulsifier type and concentration are discussed. 

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