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  • 1
    Electronic Resource
    Electronic Resource
    Degradation of polymer mixtures. VIII. Blends of poly(vinyl acetate) with poly(methyl methacrylate) (1976)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 14 (1976), S. 1839-1856 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The degradation of blends of PVA and PMMA in the form of films cast from a common solution of the polymers has been studied by TVA, TG, and EGA (evolved gas analysis) for acetic acid. Volatile degradation products have been characterized by spectroscopic and GLC techniques. Molecular weight, spectral and thermal stability changes in PMMA extracted from partially degraded blends have been examined. These blends behave in a closely analogous manner to PVC-PMMA blends already investigated. The results suggest that the PMMA component of the heterogeneous blends is modified in two ways: (1) in a destabilization reaction series initiated by attack of acetate radicals generated in the PVA phase which migrate into the PMMA phase, and (2) in a stabilization reaction involving conversion of ester side groups to acid and subsequently to anhydride ring structures which act as blocking points for depolymerization. The rate of acetic acid production in the blend is less than in PVA degraded alone. The mechanism of degradation of PVA is reconsidered in the light of these results.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1976.170140804
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  • 2
    Electronic Resource
    Electronic Resource
    Degradation of polymer mixtures. VII. Blends of poly(vinyl acetate) with polystyrene (1976)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 14 (1976), S. 603-608 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The degradation of films containing both PVA and PS has been investigated for comparison with the behavior already reported for PVC/PS blends. The presence of PS had little, if any, effect on the behavior of PVA, but PVA had an effect similar to that of PVC on the degradation of PS. Styrene production was retarded in the blend, compared to PS alone, and an increase in the rate of chain scission was observed for a high molecular weight sample. The molecular weight effect, however, was much smaller than in corresponding experiments with PVC/PS blends. Interference with intermolecular transfer in PS is again advanced as the probable explanation of the stabilization of PS.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1976.170140309
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  • 3
    Electronic Resource
    Electronic Resource
    Degradation of polymer mixtures. IV. Blends of poly(vinyl acetate) with poly(vinyl chloride) and other chlorine-containing polymers (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 12 (1974), S. 387-400 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The degradation of the binary polymer blends, poly(vinyl acetate)/poly(vinyl chloride), poly(vinyl acetate)/poly(vinylidene chloride) and poly(vinyl acetate)/polychloroprene has been studied by using thermal volatilization analysis, thermogravimetry, evolved gas analysis for hydrogen chloride and acetic acid, and spectroscopic methods. For the first two systems named, strong interaction occurs in the degrading blend, but the polychloroprene blends showed no indication of interaction. In the PVA/PVC and PVA/PVDC blends, hydrogen chloride from the chlorinated polymer causes substantial acceleration in the deacetylation of PVA. Acetic acid from PVA destabilizes PVC but has little effect in the case of PVDC because of the widely differing degradation temperatures of PVA and PVDC. The presence of hydrogen chloride during the degradation of PVA results in the formation of longer conjugated sequences, and the regression in sequence length at high extents of deacetylation found for PVA degraded alone is not observed.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1974.170120211
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  • 4
    Electronic Resource
    Electronic Resource
    Thermal degradation of mixtures of poly(methyl methacrylate) and silver acetate (1978)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 16 (1978), S. 2225-2235 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The degradation behavior of silver acetate - PMMA blends at salt/polymer ratios of 1:1, 1:5, and 1:10 has been studied by using thermal volatilization analysis (TVA) as the principal technique. Degradation of the salt has also been examined; it gives a variety of products best explained by a series of reactions resulting from an initial cleavage of CH3COO. radicals and silver atoms. Silver acetate, when present with PMMA during degradation, results in a severe destabilization of the polymer, which breaks down to monomer at a high rate at temperatures as low as 200°C. This effect is explained by diffusion of radicals from silver acetate decomposition into the polymer phase, in which they initiate chain scission and depolymerization.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1978.170160912
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  • 5
    Electronic Resource
    Electronic Resource
    Application of the porous-sphere hydrodynamic model to dilute polymer solutions (1980)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 18 (1980), S. 1781-1790 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The porous-sphere model of Debye-Brinkman-Bueche is applied to predict the limiting frictional coefficient f0 and intrinsic viscosity [η] of polystyrene fractions in tetrahydrofuran and random protein coils in 6M guanidine hydrochloride. Following the formulation of Wiegel and Mijnlieff, the molecular permeability is modeled to increase exponentially as the square of the distance from the center of the molecule. A method is developed to obtain this permeability from the translational diffusion coefficient. The experimental values of f0 and [η] are in satisfactory agreement with the calculated values. Also, this analysis predicts values of the Mandelkern-Flory-Scheraga parameter for flexible coils which are significantly smaller than the minimum values permitted by the Kirkwood-Riseman theory. This is in accord with the experimental evidence.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1980.180180810
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  • 6
    Electronic Resource
    Electronic Resource
    Comment on the concentration and temperature dependences of the translational diffusion coefficient of flexible-coil macromolecules in solution: Poly(2-vinyl pyridine) in tetrahydrofuran (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 2311-2317 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Concentration-dependence coefficients kDφ of the mutual diffusion coefficient of poly(2-vinyl pyridine) in tetrahydrofuran in the temperature range 15-55°C are compared with predictions of recent theories of macromolecular diffusion. In this temperature range a change in local conformation of the polymer occurs. The accompanying changes in chain solvation and coil hydrodynamics result in a sizable decrease in the hydrodynamic interaction parameter X defined by Akcasu. The formulation of theory appropriate for comparison with frame-indifferent experimental diffusivities is discussed. We find that current theories predict qualitatively, but not quantitatively, the change in temperature dependence of kDφ that occurs at the conformational transition. The discrepancies closely parallel those reported in recent independent comparisons of theoretical kDφ versus experimental data for flexible-coil molecules. No theory can adequately predict kDφ over a wide range of X.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1983.180211108
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  • 7
    Electronic Resource
    Electronic Resource
    High-resolution solid-state 13C-NMR spectroscopy of cellulose nitrates (1985)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 483-492 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Solid-state 13C-NMR spectroscopy has been used to investigate the structure of cellulose nitrates prepared from cotton linters. The solid-state technique has the advantage that the entire range of substitution can be studied, which is not possible at present by solution methods. The spectra change progressively with increasing degree of substitution (DOS = 3 for cellulose trinitrate), and can be used to quantify the extent of substitution at C6, C2, and C3. Progressive nitration leads to elimination of the original C6 resonances of native cellulose by DOS = 1.39. The first nitration of C6 occurs in the amorphous regions, and this is complete by DOS = 0.50. Substitution at C6 is accompanied by decrystallization, as indicated by the decrease in the resonance assigned to crystalline C4, which also disappears at DOS = 1.39. A new resonance assigned to C1 appears at DOS = 0.28 at 101 ppm; the original C1 resonance for cellulose declines steadily and disappears by DOS = 2.65. This change is assigned to nitration of C2, based on the published solution spectra. Finally, development of intensity at 82 ppm at DOS = 1.83 is assigned to the effect of nitration at C3. There is no indication of any rearrangement of the unsubstituted regions analogous to those that occur on Mercerization of native cellulose.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1985.180230306
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  • 8
    Electronic Resource
    Electronic Resource
    Study of free volume in high-vinyl polybutadiene/cis-polyisoprene blends using positron annihilation spectroscopy (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 861-871 
    Details
    ISSN: 0887-6266
    Keywords: glass transition ; polymer blends ; free volume ; positron annihilation ; composition dependence of Tg ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: High-Vinyl Polybutadiene (HVBD)/cis-Polyisoprene (CPI) blends were characterized by Differential Scanning Calorimetry (DSC) and Positron Annihilation Lifetime Spectroscopy (PALS). A single DSC glass transition temperature Tg is observed, whose composition dependence strongly deviates from additivity, and shows an apparent cusp when the weight fraction of HVBD ≈ 0.75. The free-volume hole size, Vh, and the scaled fractional free volume, hps/C, = I3Vh were determined by PALS from the orthopositronium (o-Ps) intensities, I3, and lifetimes, τ3, over a temperature range encompassing Tg and the temperature at which “positronium bubble” formation occurs. In the glass, Vh and hps/C are smaller for CPI than for HVBD, but the thermal expansion coefficient for hole volume, αf, is larger in the melt for CPI than for HVBD; thus, an iso-hole volume temperature occurs in these blends at Tiso ≈ -34°C. Above and below Tiso, Vh and hps/C each show a negative departure from additivity. A quantitative interpretation of the cusp in the composition dependence of Tg can be obtained, via a modified analysis of Kovacs, using free-volume quantities from PALS, with the ratio of scaling constants CCPI/CHVBD as an adjustable parameter. At high temperatures, the positron bubble size is smaller in CPI than in HVBD. This agrees with the observation that the thermal expansivity of hole volume, and, hence the internal pressure are larger in the equilibrium melt of CPI. The effect of e+-irradiation on the o-Ps intensity was investigated. I3 decreases more rapidly in the melt as T → Tg, and then more slowly in the glass, suggesting that the effect is due to trapping of radical or ionic species which inhibit o-Ps formation. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 861-871, 1998
    Additional Material: 6 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Influence of chain conformation on translational diffusion of poly(2-vinyl pyridine) in dilute solution (1980)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 18 (1980), S. 607-617 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A comparative photon correlation spectroscopy study is reported of the concentration-dependent translational diffusion coefficient Dt of atactic poly(2-vinyl pyridine) in tetrahydrofuran and in aqueous solution, in the form of the poly(2-vinyl pyridinium)chloride salt (α = 0.4). The limiting Stokes radius of the polymer is observed to be identical within experimental error in tetrahydrofuran (THF) at temperatures below 30°C and in aqueous solutions at high ionic strength. This numerical value is comparable to expectation for an unperturbed atactic vinyl polymer chain and indicates a compact, possibly micellar, conformation. Raising the temperature in THF above 30°C and decreasing the ionic strength or increasing the ionization above α = 0.4 in aqueous solvents causes a discontinuous cooperative transition to a more expanded structure. The effect of the conformational change is also manifest in the concentration dependence of Dt. Using experimental estimates of the second osmotic virial coefficients obtained by total scattered intensity measurements, the experimental data for dDt/dc are compared with prediction based on hydrodynamic theory. Substantial disagreement is found between theory and experiment, especially in the aqueous system. In 0.01M NaCl, decrease in polyion concentration induces the transition from the compact form to a highly extended structure. Angle-dependent quasielastic light scattering data from the expanded state provides information about the intramolecular chain dynamics.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1980.180180319
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  • 10
    Electronic Resource
    Electronic Resource
    Dynamical behavior of xanthan polysaccharide in solutionPaper presented at A.I.Ch.E. National Meeting, March 1981, Houston, TX.Corrected proofs received June 23, 1982 (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1513-1524 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Dilute-solution hydrodynamic data for xanthan biopolymer in water suggest a rodlike molecule of dimensions 15,000 × 20 Å, and molecular weight 2.2 × 106 g/mol. Upon addition of NaCl to this system, the xanthan molecules self-associate to form stable aggregates. The native xanthan conformation can be thermally denatured to a disordered coil which can be stabilized at room temperature in 4M urea. The transition to semidilute solutions is manifested by discrete changes in the concentration dependence of diffusion coefficient and zero-shear viscosity at c ≈ 2.0 × 10-4 g/mL. At higher concentrations c ≥ 1.0 × 10-3 g/mL, the light-scattering and shear-viscosity data are qualitatively but not quantitatively consistent with predictions of the dynamical theory of Doi and Edwards for an isotropic entangled solution of rigid-rod molecules. Measurements of latex sphere diffusion in xanthan-water solution show a sudden retardation at c ≈ 1.0 × 10-3 g/mL, consistent with the cooperative formation of a motionally restricted network of long, thin, rigid fibers. At high shear rates, flow birefringence experiments indicate enhanced ordering of the xanthan chains in the semidilute regime.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1982.180200901
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