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  • 1
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 2911-2921 
    ISSN: 0887-6266
    Keywords: epoxy ; amine ; microdielectrometry ; conductivity ; conversion ; glass transition temperature ; curing ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Three reactive epoxy-amine systems based on diglycidyl ether of bisphenol A (DGEBA) with 4,4′-diaminodiphenylsulfone (DDS), 4,4′-methylenebis [3-chloro 2,6-diethylaniline] (MCDEA), and 4,4′-methylenebis [2,6-diethylaniline] (MDEA), were studied during isothermal curings at 140 and 160°C. The simultaneous kinetic and dielectric studies allow to express conductivity, σ, in terms of conversion, x, and of glass transition temperature, Tg. The conductivity, σ0, of the initial monomer mixture and, σ∞ of the fully cured network are measured. It is found that: The glass transition temperature, Tg, versus conversion, x, curves follows the equation of Di Benedetto modified by Pascault and WilliamsThere exists a linear relation between log σ/log σ0 and Tg.So, it is possible to predict both kinetic and dielectric behaviors of these epoxy-amine systems by the knowledge of Tg0, ΔCp0, and σ0, respectively, glass transition temperature, heat capacity, and conductivity of initial monomer mixture, Tg∞ and ΔCp∞, and σ∞, respectively, glass transition temperature and heat capacity and conductivity of fully cured network. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 2911-2921, 1998
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 305-310 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The enchanced low-shear melt viscosity of branched polybutadienes is shown to be sensitive to dilution with low molecular compounds. The viscosity of branched polymers falls more rapidly with dilution than that of linear polymers, i.e., branched polymers show increased response to plasticization. At least one instance is demonstrated in which the viscosity ratio ηbr/ηlin reverses from a value greater than unity to less than one in passing from dry polymer to rubber extended with relatively large quantities of oil.
    Additional Material: 3 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 571-581 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The thermal expansion of a butadiene-styrene copolymer filled with carbon blacks differing tenfold in mean particle size (HAF and MT) was investigated. The glass transition was unaffected by MT and was raised only 0.2°C for every 10 parts per hundred by weight of polymer of HAF black added. The coefficient of expansion of the polymer component of the composite in the rubbery region was substantially unaffected by either carbon black, but decreased markedly with increasing black loading in the glassy state. These results suggest that free volume is not altered appreciably by the presence of the filler in the rubbery state, but expands with decreasing temperature below Tg. The latter effect is explained by dilatation due to stresses set up around filler particles, arising from differences in the expansion coefficients of filler and polymer, which are not relieved in the glassy state. The near invariability of Tg and of the rubbery fected by adsorption of polymer segments on the carbon black surface. A conservative rough estimate indicates that restriction of segmental motion is confined to a 30 Å layer around the particles in which Tg is elevated by only 10°C.
    Additional Material: 4 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 10 (1972), S. 657-672 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A method described for the determination of molecular weight and long-chain branching distributions of polymers requires no prior knowledge of the functional relation between branching frequency and molecular weight. It is based on preparative fractionation and viscometric and gel-permeation chromatographic measurements on both fractions and whole polymer. The technique is applied to several polybutadienes and butadiene-styrene copolymers differing widely in method of synthesis and pattern of long-chain branching.
    Additional Material: 12 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 9 (1971), S. 1839-1850 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Steady flow and dynamic viscosities were determined for symmetrical linear and starbranched block copolymers of butadiene and styrene above their upper (polystyrene) glass transition. Block structures examined were B-S-B, (B-S-)3, S-B-S, (S-B-)3 and (S-B-)4. At constant molecular weight and total styrene content viscosities were greater for polymers terminating in styrene blocks, irrespective of branching. Branching decreased the viscosity of either polybutadiene-terminated or polystyrene-terminated block polymers, compared at equal Mw. However, comparisons at equal block lengths showed that the length of the terminal blocks, not the total molecular weight, governs the viscoelastic behavior of these polymers to a surprisingly good approximation. This unusual result is rationalized in terms of the two-phase domain structure of these polymers, which persists to a significant degree in the melt. Below the glass transition of the polystyrene blocks the effects of branching were masked by differences in the morphology of the domain structure unrelated to branching.
    Additional Material: 9 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 35 (1997), S. 1349-1359 
    ISSN: 0887-6266
    Keywords: composite ; dielectric relaxation ; MWS relaxation ; percolation ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Dielectric spectrometry experiments are performed on a series of polystyrene-glass bead composites with volume filler content from 0 to 50% and with three particle diameters (5 μm, 20 μm, and 90 μm) in order to study the Maxwell-Wagner-Sillars (MWS) relaxations and the percolation phenomena. In the high-temperature region (130 to 220°C), the experimental data give evidence of MWS relaxations for all the composite systems, whatever the bead size and the filler content are. A good agreement is found between the experimental values of the maximum loss factor frequency and the theoretical ones drawn from the van Beek formula, especially for low contents. A percolation phenomenon is shown in the low-temperature region (40 to 120°C) for high-content/low-size composites. The percolation threshold, determined by considering the critical interparticle distance, is below 15.0% for the 5μm glass bead composites and above 47.3% for the 90 μm composites; it lies between 20.5 and 28.6% for the 20 μm composites. Two schematic models, based on a distribution of the sizes and on a random dispersion of the beads, are developed to show how MWS and percolation phenomena can both be observed for the high-content/low-size composites. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 1349-1359, 1997
    Additional Material: 9 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 10 (1972), S. 2009-2024 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The kinetics of the strain-induced crystallization of a crosslinked 89% trans-polypentenamer was studied as a function of temperature and strain by using a combined birefringence - stress relaxation technique. The crystallization rate was found to be extremely sensitive to both variables and was, within experimental error, a function of the degree of undercooling alone, the increase in crystallization rate with strain being a direct consequence of the melting point elevation. From the isothermal, isometric crystallization rates, the development of crystallinity in constant-rate-of-strain experiments was calculated and related to characteristics of the stress--strain curve and of the temperature-strain rate dependence of tensile strength. These calculations allow one to estimate under what conditions sufficient crystallinity may be expected for the attainment of high strength in absence of reinforcing fillers. Crystallinities measured in this work were of the order of 10% or less. A limited x-ray diffraction study confirmed the low order of crystallinity indicated by the stress-birefringence measurements. The relatively high precision of the latter makes this technique attractive for the estimation of small straininduced crystallinities in rubbers.
    Additional Material: 11 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 385-388 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 4 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 1133-1148 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Dynamic viscoelastic properties of block copolymers of styrene with butadiene or isoprene are consistent with the growth of a diffuse interphase or interlayer as block lengths decrease. Under the conditions of the present study the interlayer does not lead to a secondary loss maximum between the two domain glass transitions. The pattern of shifts of the loss maxima characteristic of the domain Tg's suggests strongly that the interlayer composition profile must be asymmetric with an average volume composition rich in styrene. Typical block polymer viscoelastic behavior is observed even beyond the point at which the interlayer attains 100% of the polymer volume. Such block polymers no longer contain compositionally pure phases, but are visualized as retaining a residual domain structure in which composition fluctuates between ever narrowing limits as blocks become shorter, approaching homogeneity and the mechanical behavior of random copolymers.
    Additional Material: 14 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 10 (1972), S. 2061-2072 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Dynamic viscoelastic properties of S - B - S block copolymers were measured in the tensile and shear deformation modes. Between the glass transitions of the polybutadiene and polystyrene domains the ratio of storage moduli E'/G' in tension and in shear for the same polymer varied from 3 to more than 30, depending on sample preparation. For films cast from good solvents this ratio was near 3; large ratios resulted from deposition from poor polybutadiene solvents or from compression molding. Above the polystyrene glass transition, E'/G' approached 3 for all samples. The effect is ascribed to various degrees of polystyrene domain connectivity. Electron micrographs confirm this interpretation. For morphologies of high polystyrene domain connectivity, the loss tangent in tension is heavily weighted by mechanical losses in the polystyrene phase; the loss tangent in shear is affected only moderately by differences in domain morphology.
    Additional Material: 9 Ill.
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