Polymer deductions

Masda, L. and Xanthos, M A. 1992. Overview of additives and modifiers for polymer blends facts, deductions, and imcertainties. Advances in Polymer Technology 11 237-248. 

The statistical approach has since assumed a dominant role in the treatment of the constitution, reactions, and physical properties of polymeric substances. The complexities of high polymers are far too great for a direct mechanistic deduction of properties from the detailed structures of the constituent molecules even the constitution of... 

The highly important deduction that one-half of the polymer particles will contain a single growing radical and the other half will contain none at any given time was first set forth by Smith and Ewart. They immediately pointed out that the rate of polymerization per cubic centimeter of water should then be given by... 

The determination of the turbidity of polymer solutions will be discussed briefly in the following pages, and the essentials involved in the deduction of molecular weights and molecular dimensions will... 

More simple solutions are found for special cases. Already in 1933 Kratky [248] has presented a method for the case in which the observed orientation distribution has its maximum on the equator. In 1979 the problem treated by Kratky has been revisited by Leadbetter and Norris [254], They present a different solution which is frequently applied in studies of liquid-crystalline polymers. Burger and Ru-land [255] pinpoint the error in the deduction of Leadbetter and... 

Because all the above deductions are valid for infinite low polymer concentrations but practical measurements have to be carried out at finite values of c, it is necessary to include the second virial coefficient A2. Thus the equation according to which evaluation of light-scattering experiments can be done is ... 

The value of the modulus and the shape of the modulus curve allow deductions concerning not only the state of aggregation but also the structure of polymers. Thus, by means of torsion-oscillation measurements, one can determine the proportions of amorphous and crystalline regions, crosslinking and chemical non-uniformity, and can distinguish random copolymers from block copolymers. This procedure is also very suitable for the investigation of plasticized or filled polymers, as well as for the characterization of mixtures of different polymers (polymer blends). 

The results of the scattering experiments are shown in Table 2.1. They leave little room for doubt as to the essential correctness of Flory s deduction about chain dimensions in undiluted polymers. 

The effect of polymer concentration on [M]e has also been shown in the study of Tobolsky et al. (35). Unfortunately, their experimental technique was not sufficiently refined, and the wide scatter of experimental points prevented quantitative deductions from their data. Comment is necessary with respect to one statement made in their paper. The authors assumed that the "true value of [M]e could be derived by linear extrapolation from the experimental [M]e s, obtained at high polymer concentrations, up to the point of intersection with the line [M]e= [M]0. However, this extrapolation is not valid because, as has been shown by Vrancken et al. (13), the results depend on the concentration of living ends. The proper determination of the true [M]e requires studies at low concentrations of living ends, as was done by Worsfold and Bywater (12) and by McCormick (11). 

Product analysis supports these deductions [20]. At lower acidities (pH 2-5), o-cresol gives mainly products by one-electron transfer (PI and P2). At higher acidities (pH < 2), however, 4-chlorophenol forms P4 as the major product, with some P5 and P6, but only a minor amount of P2 and traces of polymers P3. 

Although the crystalline structures of many polymers have been determined, it is unusual for these to include any estimate of the probable error in the various parameters. But unless these are known, deductions which are sometimes made from the values of the parameters (e.g. the assignment of infra-red absorption band frequencies) can be misleading. 

L. Mascia and M. Xanthos, An Overview of Additives and Modifiers for Polymer Blends Facts, Deductions, and Uncertainties, Adv. Polym. Technol., 11, 237-248 (1992). 

In his kinetic analysis of the copolymer composition that would be formed, the usual steady-state assumptions were made. Lowry also made the important deduction that the rate at which Monomer 2 disappeared from the reaction (and was incorporated into the polymer) depended not simply upon the relative rates of the forward and reverse reaction (4a)... 

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