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  • Physics  (568)
  • Magnetism
  • Wiley-Blackwell  (576)
  • American Physical Society (APS)
  • Springer Nature
  • World Scientific
  • 1995-1999  (576)
  • 11
    Electronic Resource
    Electronic Resource
    Viscoelasticity and self-diffusion in melts of entangled linear polymers (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 35 (1997), S. 1933-1942 
    Details
    ISSN: 0887-6266
    Keywords: self-diffusion ; viscosity ; polymer melt ; entanglement ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Dynamic properties in the melt state for two saturated hydrocarbon polymers, poly(ethylene-alt-propylene) (PEP) and head-to-head polypropylene (HHPP), were investigated by viscoelastic and diffusion measurements. Several nearly monodisperse linear samples of each species were used. Zero-shear viscosity η0 and self-diffusion coefficient D varied with temperature in accord with the WLF equation, and they also varied with molecular weight M in a manner that was consistent with the behavior of other species. The product η0D was of particular interest because extensive previous results for two other species, polystyrene and polyethylene, had led Pearson et al. to suggest that η0D/(η0D)Rouse is a universal function of the number of entanglements per molecule M/Me. With values for the Rouse model product for each species calculated from chain dimensions, and entanglement molecular weight from the plateau modulus, we show that the data for PEP and HHPP also support the Pearson universal form. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 1933-1942, 1997
    Additional Material: 6 Ill.
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  • 12
    Electronic Resource
    Electronic Resource
    Dynamic mechanical behavior of fluorinated aromatic poly(ethers) (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 35 (1997), S. 1963-1971 
    Details
    ISSN: 0887-6266
    Keywords: dynamic mechanical analysis ; fluorinated poly(ethers) ; intermolecular cooperativity ; relaxation behavior ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The relaxation behavior of six fluorinated aromatic poly(ethers) was investigated using dynamic mechanical analysis. The glass transition temperature was found to increase as the size and rigidity of linking groups increased and varied between 168°C for a dimethyl linking group and 300°C for a bicyclic benzoate ether-linking group. For the α-relaxation the steepness of time/temperature plots and broadness of the loss curves could be qualitatively correlated with chemical structure in a manner predicted by the coupling model of relaxation. Well-separated sub-Tg transitions were also observed, as a shoulder on the low temperature side of the α-peak, and as a broad, low loss transition around -100°C. The higher temperature process was similar to the structural relaxation often found in quenched glassy polymers, while the position, intensity, and breadth of the subambient process was sensitive to chemical structure. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 1963-1971, 1997
    Additional Material: 7 Ill.
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  • 13
    Electronic Resource
    Electronic Resource
    FTIR studies of conformational energies of poly(acrylic acid) in cast films (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 35 (1997), S. 507-515 
    Details
    ISSN: 0887-6266
    Keywords: poly(acrylic acid) ; FTIR ; polyelectrolyte ; conformation ; conformers ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Fourier transform infrared (FTIR) spectroscopic measurements have been undertaken to estimate the conformational energies of poly(acrylic acid) (PAA) cast films in the temperature range of 40-130°C. The temperature dependence of the IR spectra in the C=O stretching region has been analyzed to yield the side-chain and backbone conformational energies. The estimated energies are close to those previously obtained by polarized Raman spectroscopic measurements for PAA solutions. Combining the FTIR value of conformational energy with the simplified rotational isomeric state (RIS) model proposed in the Raman analysis provides a persistence length in accordance with earlier SAXS experiments. The data also agree with the Gibbs-DiMarzio predictions, further substantiating the validity of the analysis. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys, 35: 507-515, 1997
    Additional Material: 7 Ill.
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  • 14
    Electronic Resource
    Electronic Resource
    Computer-simulation analysis of the ESR spectra of mechanoradicals in PMMA (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 35 (1997), S. 2195-2200 
    Details
    ISSN: 0887-6266
    Keywords: ESR ; mechanoradicals ; PMMA ; drilling apparatus ; computer simulation ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In this study, initially, we tried to obtain the mechanoradicals of PMMA (poly(methyl methacrylate)). For this purpose, we designed a simple drilling apparatus. Using this apparatus, we prepared some PMMA samples at 77 K in vacuum. Later, by using an ESR (electron spin resonance spectrometer), we observed ESR signals for these samples at 77 K. This means that mechanoradicals have been successfully produced by mechanical fracture in PMMA using our drilling apparatus. Secondly, we tried to identify the radicals from these spectra through using theoretical analyses and, some computer simulations have been done by suggesting two different theoretical models for these ESR signals. Finally, by using experimental and theoretical data, we showed that our simple apparatus could be used to obtain mechanoradicals from polymers. Results were seen to be in very good agreement with the literature. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 2195-2200, 1997
    Additional Material: 5 Ill.
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  • 15
    Electronic Resource
    Electronic Resource
    Measurement of crystalline index in nylons by DSC: Complexities and recommendations (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 35 (1997), S. 2219-2231 
    Details
    ISSN: 0887-6266
    Keywords: nylons ; crystallinity ; DSC ; x-ray diffraction ; complications ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Differential scanning calorimetry (DSC) is one of the most widely used technique for measuring crystallinity in the polymer industry. The major source of error in the crystalline index (CIDSC) of low crystallinity polymeric articles, is the development of further crystallinity during the DSC scan. Although, this type of cold crystallization is obvious, and thus accounted for in polymers like polyethylene terephthalate, nylons are a difficult class of materials in that respect. The major contributing factors to the failure of DSC in measuring low levels of crystallinity in nylons are identified to be (1) silent crystallization between the glass (Tg) and melting (Tm) transitions, (2) extreme difficulties in packing a moisture-free nylon in the sample pan (the response due to traces of moisture being a broad endotherm competing with a broad exothermic crystallization), and (3) a sub-Tm exotherm, especially in low crystallinity nylons, due to relaxation of the processing-induced stresses. These factors, specific to nylons, mask the observation of cold crystallization and lead to substantially higher than real crystallinities. This manuscript deals with such complications and corrective actions using commercial nylon 6 films of CIDSC = 0-40%. X-ray diffraction measurements have been included to support the validity of our improved DSC methodology. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 2219-2231, 1997
    Additional Material: 9 Ill.
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  • 16
    Electronic Resource
    Electronic Resource
    Heat capacity and phonon dispersion in poly(L-methionine) (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 35 (1997), S. 2281-2292 
    Details
    ISSN: 0887-6266
    Keywords: conformation ; phonon dispersion ; α-helix ; normal modes ; poly(L-leucine) ; density of states ; heat capacity ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Poly(L-methionine) (PMet) is one of the two sulfur containing polyamino acids. Raman, FTIR spectra, and heat capacity measurements of PMet have been well interpreted through the normal mode analysis and the density of states derived therefrom. Earlier interpretation of heat capacity data is limited because it is based on the Tarasov model, wherein the concept of group frequency and skeletal similarity are used. A special feature of some dispersion curves is their tendency to bunch in the neighborhood of the helix angle. This has been attributed to the presence of strong intramolecular interactions. Repulsion between the dispersion curves is also observed. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 2281-2292, 1997
    Additional Material: 6 Ill.
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  • 17
    Electronic Resource
    Electronic Resource
    Use of “living” radical polymerizations to study the structural evolution and properties of highly crosslinked polymer networks (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 35 (1997), S. 2297-2307 
    Details
    ISSN: 0887-6266
    Keywords: crosslinked polymers ; photopolymerizations ; living radical polymerizations ; mechanical properties ; dynamic mechanical analysis ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Crosslinked polymer networks are used in a wide variety of applications. To use these materials effectively, a fundamental understanding of their structural evolution and the relationship between material properties and structure is essential. In this article, a novel technique employing “iniferters,” i.e., living radical polymerizations, to photopolymerize these networks is utilized to study the property and structural evolution of these highly desirable materials. Living radical polymerizations are used in this work since this technique avoids the problem of carbon radical trapping encountered while using conventional initiators. Dynamic mechanical measurements are performed on highly crosslinked methacrylate networks to glean information regarding their structural heterogeneity. By performing these measurements on homopolymerized samples at various stages of the reaction and on copolymerized samples of multifunctional methacrylates, the mechanical properties are characterized as a function of double bond conversion and comonomer composition. From such analyses, with respect to both temperature and frequency, quantitative conclusions regarding the structure of the networks are drawn. This effort is aimed at exploiting the living radical polymerizations initiated by p-xylylene bis(N,N-diethyl dithiocarbamate) (XDT), to study the mechanical property evolution and structural heterogeneity of crosslinked polymers which is nearly impossible otherwise. Polymers examined in this study include networks formed by homopolymerization of diethylene glycol dimethacrylate (DEGDMA) and polyethylene glycol 600 dimethacrylate (PEG600DMA) as well as copolymers of DEGDMA and PEG600DMA. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 2297-2307, 1997
    Additional Material: 8 Ill.
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  • 18
    Electronic Resource
    Electronic Resource
    Probing the microstructure of Nafion-117 using positron annihilation spectroscopy (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 35 (1997), S. 771-776 
    Details
    ISSN: 0887-6266
    Keywords: Nafion ; positron annihilation ; free volume ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: We report a new result on positron annihilation studies in acid- and cation-neutralized (Li+, Na+, K+, Rb+, Cs+, UO22+, Ni2+) Nafion membranes using positron lifetime and Doppler-broadened annihilation radiation (DBAR) measurements. The free-volume structure is characterized using a simple quantum mechanical model of positronium (Ps) in a spherical well. Our studies indicate that formation and expansion of clusters is always associated with a change in free-volume structure resulting in smaller free-volume holes. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 771-776, 1997
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  • 19
    Electronic Resource
    Electronic Resource
    Blends of bisphenol-A polycarbonate and acrylic polymers: III. Effect of imide concentration on compatibility (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 35 (1997), S. 749-761 
    Details
    ISSN: 0887-6266
    Keywords: polycarbonate ; polyglutanimide ; polymer blends ; copolymer ; compatibilization ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Imide units copolymerized with MMA units have been selected in order to improve compatibility between PC and acrylics through specific interaction or internal repulsion. Good dispersion of acrylic inside a PC matrix has been observed upon melt mixing, which can be partially explained by the good rheological agreement between these two polymers. Transmission electron microscopy has shown that the system remains phase separated from 5 to 95 wt % of PC. Phase diagrams for three different imide concentrations have been drawn. Results obtained by DSC (conventional and with enthalpy relaxation) are similar to those obtained by optical cloud point detection. The phase diagrams show the raise of the PC/PMMA demixtion curve (LCST type) when percentage of imide increases in the acrylic phase. Theoretical calculations on binary interaction energy density show a slight improvement of the interaction between acrylic and PC when imide percentage increases. Cloud point measurements on 50/50 PC/acrylic blends varying the imide concentration show that the improvement of compatibility deduced from the raise of the demixtion curve (LCST type) is more related to a kinetic effect (the high Tg of imidized samples is reducing macromolecule mobility) than specific interactions. The calculated favorable interactions are probably too weak to be detected with cloud point measurements. The microstructures obtained after crystallization of the PC phase under solvent vapors in phase separated PC/acrylics blends can also be explained by Tg effects. Moreover, solvent vapor exposure could be a powerful tool to determine the real thermodynamic behavior of the blends at room temperature. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 749-761, 1997
    Additional Material: 19 Ill.
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  • 20
    Electronic Resource
    Electronic Resource
    A process-structure-property study of anisotropic PMDA-ODA films (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 35 (1997), S. 777-788 
    Details
    ISSN: 0887-6266
    Keywords: PMDA-ODA polyimide ; intrinsic molecular properties ; sheet mapping ; fabrication processes ; three-dimensional orientation functions ; anisotropic coefficient of thermal expansion (CTE) ; anisotropic mechanical moduli ; anisotropic compliances ; anisotropic dielectric constants ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A practical methodology for the correlation and prediction of the process-property performance of advanced materials is developed. The model polymer studied is PMDA-ODA polyimide. The connecting link between the process and the properties is the structural state of the polymer. An essential ingredient for a quantitative characterization of the system is a knowledge of its phase state and intrinsic molecular properties. The intrinsic molecular properties define the limiting performance properties available to the polymer. Anisotropic films and sheets produced by five different fabrication processes are examined. Maps of the molecular symmetry axis, the orientation function, and the thickness distributions of two 50-in.-wide sheets fabricated differently are measured nondestructively for process comparison. Four other film fabrication processes are examined and their three-dimensional orientation states determined and correlated. A three-dimensional orientation function triangular plot permits simultaneous representation of the different fabrication processes on the same figure and allows the investigator to choose the most economic and efficient fabrication route. The structure-property study includes the structural correlation and intrinsic molecular property determination of the anisotropic coefficient of thermal expansion (CTE), the anisotropic mechanical moduli and compliances, and the anisotropic dielectric constants. 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 777-788, 1997
    Additional Material: 17 Ill.
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