Polymers comparison

A simple algorithm [17] makes it possible to find the probability of any fragment of macromolecules of Gordonian polymers. Comparison of these probabilities with the data obtained by NMR spectroscopy provides the possibility to evaluate the adequacy of a chosen kinetic model of a synthesis process of a particular polymer specimen. The above-mentioned probabilities are also involved in the expressions for the glass transition temperature and some structure-additive properties of branched polymers [18,19]. 

E. Evans and D. Needham Attraction Between Lipid BUayer Membranes in Concentrated Solutions of Nonadsorbing Polymers Comparison of Mean-Field Theory with Measurements of Adhesion Energy. Macromolecules 21, 1822 (1988). 

Zhang H, Dubin PL, Kaplan J, Moorefield CN, Newkome GR. Dissociation of carboxyl-terminated cascade polymers comparison with theory. J Phys Chem B 1997 101 3494-3497. 

Here is Boltzmann s constant, or the gas constant per molecule, R/Nq, where No is Avogadro s number (or Na + Nb for one mole of solution) and va and are the volume fractions of solvent and polymer. Comparison of Eq. (2.76) with the entropy of mixing presented earlier in the chapter by Eq. (2.30) shows that they are similar in form, except that now the volume fractions of the components, va and vg, are found to be the most convenient way of expressing the entropy change for polymers, rather than the mole fraction used for most small molecules. This change arises from the differences in size between the large polymer molecules and the small solvent molecules which would normally mean mole fractions close to unity for the solvent, especially when dilute solutions are being studied. 

Effects of polymer structure on reaction of phenylacetonitrile with excess 1-bromo-butane and 50% NaOH have been studied under conditions of constant particle size and 500 rpm stirring to prevent mass transfer limitations I03). All experiments used benzyltrimethylammonium ion catalysts 2 and addition of phenylacetonitrile before addition of 1-bromobutane as described earlier. With 16-17% RS the rate constant with a 10 % CL polymer was 0.033 times that with a 2 % CL polymer. Comparisons of 2 % CL catalysts with different % RS and Amberlyst macroporous ion exchange resins are in Table 6. The catalysts with at least 40% RS were more active that with 16 % RS, opposite to the relative activities in most nucleophilic displacement reactions. If the macroporous ion exchange resins were available in small particle sizes, they might be the most active catalysts available for alkylation of phenylacetonitrile. 

Water Vapor transmission. Table 3 lists water vapor transmission (WVTR) values for selected polymers. Comparison of Tables 1 and 3 shows that often there is a reversal of roles. Those polymers that are good oxygen barriers are often poor waler-vapor barriers and vice versa. This can be rationalized as follows. Barrier polymers often rely on dipole-dipole interactions to reduce chain mobility and, licncc, diffusional movement of pcrmcants. These dipoles can be good sites for hydrogen bonding. Water molecules are attracted to these sites. Polymer molecules without dipole—dipole interactions, such as polyolefins, dissolve very little water and have low. WVTR and permeability values. The low values of S more than compensate for the naturally higher values of D. 

TABLE 26.4 Specific heat of combustion of some polymers comparison of calculation values... 

The Mction curve depends slightly on the degree of entanglement in a given family of polymers (comparison of Figs. 4a and 4b). In addition, in the case of the LLDPE, the friction curve does not appear to depend on temperature (Fig. 4d). 

Table 3. Instability Phenomena in Amorphous Polymers Comparison between the Extension Ratio, X,", at the Initiation of Stress-Whitening and the Maximum Extension Ratio, X, of Chains between Entanglement Points...

D 18. — — — Phase separation during the formation of three-dimensional polymers. Comparison of theory with experiment. Collection Czech. Chem. Commun., im Druck. 

Polyarylether 7 was the first to be synthesized using PTC conditions. It is the most thermally stable of the three polymers. Comparisons of the TG analysis... 

Y. A. Chen and E. W. Prohofsky, Sequence and temperature dependence of the interbase hydrogen-bond breathing modes in B-DNA polymers comparison with low-frequency Raman peaks and their role in helix melting. Biopolymers, 35(6), 573-582 (1995). 

It is believed that the principal difference between the solid and liquid products is that the liquid is essentially a linear polymer, while the solid is highly cross-linked. Such a highly cross-linked polystyrene would be expected to have a lowdr ratio of aromatic C-H to aliphatic C-H bonds than would a linear polymer. Comparison of spectrum B or D with C in Figure 2 shows that the intensity of the aromatic and aliphatic C—H stretching vibrations agrees with this expectation. 

Determination of the isotopically labelled initiator fragment bound in the polymer. Comparison of inhibitor decay rate (usually FeClj, but also CUCI2 or CuBr,) with rate of Nj generation. 

Hu, J. Gao, W. Kulshrestha, A.S. Gross, R. A. Synthesis of glycerol-based oligomers and polymer Comparison between lipase and dibutyltin oxide catalyzed polymerization ACS Polymer Preprints, 2006,47(2), 279. 

Huguet, M.L. Neufeld, R. J. Dellacherie, E. Calcium-alginate beads coated with polycationic polymers Comparison of chitosan and DEAE-dextran. Process Biochem. 1996, 31 (4), 347-353. 

P. Colombo, G. A. Danko, and R. Silberglitt, Production of SiC and SiOC from preceramic polymers comparison of microwave and conventional heating, in Ceramics - Getting into the 2000s, Part C (Section F), Techna Sri, Faenza, 1998, pp. 353-360. 

D NMR of Polymers Comparison of Some of the Standard Pulse Sequences... 

Variation of the monomer structure is expected to affect the structure of the final polymer. Comparison with regularly branched dendritic polycarbosilanes will make it possible to evaluate the characteristic structure-property relationships. 

TABLE 21.1 Amount (Molar Fraction) of the Three Different Sulfonate Groups and Their Sum (Rs/r) Relative to EDT Content in Polymers. Comparison Is Made with Conductivity (o-)... 

D. Hofmann, M. Heuchel, Y. Yampolskii, V. Khotimskii, V. Shantarovich, Free volume distributions in ultrahigh and lower free volume polymers Comparison between molecular modeling and positron lifetime smdies. Macromolecules, 35, 2129-2140 (2002). 

For soluble polymers, comparison with their solution spectra offers the simplest means to assign the resonances in their CPMAS/DD solid-state spectra. On the other hand, those polymers that cannot be dissolved, melted or sufficiently swollen to provide high-resolution liquid-state spectra for comparison, can be observed in the solid with methods comparable to those developed for editing solution-state spectra. It is easier to describe these methods with the aid of a qualitative understanding of how the dilute C and abundant spins interact in a typical solid, organic sample. 

The larger - AG° values for BPYI than for MPVI (peurt (b). Table I) are attributed to the greater van der Waals dispersion forces between the dye and the benzyl group of the BPVI polymer. Comparison of TA S° for the two charged polymers with the negative value for PVI shows that... 

Annable T, Buscall R, Ettelaie R, Whittletone D. The rheology of solutions of associating polymers comparison of experimental behavior with transient network theory. J Rheol 1993 37 695-725. 

Lange U, Mirsky VM. Separated analysis of bulk and contact resistance of conducting polymers comparison of simultaneous two-and four-point measurements with impedance measurements. J Electroanal Chem 2008 622 246-251. 

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