Journal of Polymer Science Part B: Polymer Physics

Cover image for Vol. 52 Issue 10

15 May 2014

Volume 52, Issue 10

Pages i–iv, 677–736

  1. Cover Image

    1. Top of page
    2. Cover Image
    3. Review
    4. Full Papers
    1. You have free access to this content
      Cover Image, Volume 52, Issue 10 (pages i–ii)

      Article first published online: 7 APR 2014 | DOI: 10.1002/polb.23485

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      Vinyl acetate groups arrange themselves to preferentially adsorb on a fumed silica surface over ethylene groups in poly(ethylene-stat-vinyl acetate) copolymers. Temperature-modulated differential scanning calorimetry and FTIR are used by Madhubhashini Maddumaarachchi and Frank D. Blum on page 727 (DOI: 10.1002/polb.23476) to show how glass transitions, melting, and hydrogen bonding vary with the composition and the adsorbed amount of the copolymer. The cover shows the preference of the vinyl acetate carbonyls (red) hydrogen bonded to the surface. When compared as a function of vinyl acetate groups alone, all copolymers and the homo-poly(vinyl acetate) behave similarly, except at low vinyl acetate contents, which can be considered carbonyl-starved

    2. You have free access to this content
      Cover Image, Volume 52, Issue 10 (pages iii–iv)

      Article first published online: 7 APR 2014 | DOI: 10.1002/polb.23487

      Thumbnail image of graphical abstract

      The mechanical properties of isotactic polypropylene can be tailored through the control of the molecular structure and crystallization of the α form, γ form, and mesophase, as reviewed by Claudio De Rosa, Finizia Auriemma, Rocco Di Girolamo, and Odda Ruiz de Ballesteros on page 677 (DOI: 10.1002/polb.23473). The crystallization of the γ form is favored by the presence of stereodefects, whereas the mesophase crystallize by fast quenching from the melt. The different morphology of crystals of these polymorphic forms affects the mechanical behavior. Lamellar crystals of the α form produce stiff polypropylene, whereas needle-like crystals of the γ form and nodular crystals of the mesophase afford great ductility and flexibility.

  2. Review

    1. Top of page
    2. Cover Image
    3. Review
    4. Full Papers
    1. You have free access to this content
      Crystallization of the mesomorphic form and control of the molecular structure for tailoring the mechanical properties of isotactic polypropylene (pages 677–699)

      Claudio De Rosa, Finizia Auriemma, Rocco Di Girolamo and Odda Ruiz de Ballesteros

      Article first published online: 23 MAR 2014 | DOI: 10.1002/polb.23473

      Thumbnail image of graphical abstract

      The mechanical properties of isotactic polypropylene can be tailored through the control of the molecular structure by metallocene catalysts and by the crystallization and processing conditions. The properties depend on the morphology of crystals, which depend on the stereodefect concentration and crystallization of α and γ forms and on the mesophase. Nodular crystals of the mesophase and needle-like crystals of the γ form afford great ductility, whereas stiff materials are obtained with the lamellar α form.

  3. Full Papers

    1. Top of page
    2. Cover Image
    3. Review
    4. Full Papers
    1. Control of polythiophene film microstructure and charge carrier dynamics through crystallization temperature (pages 700–707)

      Hilary S. Marsh, Obadiah G. Reid, George Barnes, Martin Heeney, Natalie Stingelin and Garry Rumbles

      Article first published online: 22 MAR 2014 | DOI: 10.1002/polb.23471

      Thumbnail image of graphical abstract

      The thin-film microstructure of neat conjugated polymers is important for their use in organic photovoltaics, and has a strong impact on charge carrier dynamics. Here, control of lamellar crystal thickness in the (001)-direction and the long-range order in the (100)-direction in two polythiophenes is achieved by varying the crystallization temperature. Photoconductance transients demonstrate that films with larger crystallites have longer photoconductance lifetimes and charge carrier yield is found to decrease with increasing crystallite surface area.

    2. Effect of pressure on the flow behavior of polybutene (pages 708–715)

      Aleks Ponjavic, Luca di Mare and Janet S. S. Wong

      Article first published online: 17 MAR 2014 | DOI: 10.1002/polb.23472

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      The rheology of a confined polymer melt experiencing high normal pressure is investigated by obtaining through-thickness velocity profiles of polybutene sheared between two glass surfaces. These profiles are linear (Couette flow) at low pressure. They become sigmoidal (constricted plug flow) when a critical pressure is reached. This transition is shown to be a result of pressure-induced glass transition of polybutene. The sigmoidal-shaped profiles signify that the through-thickness viscosity of the highly stressed melt is heterogeneous.

    3. Stretching temperature and direction dependency of uniaxial deformation mechanism in overstretched polyethylene (pages 716–726)

      Lianlian Fu, Zhiyong Jiang, Hans-Friedrich Enderle, Dieter Lilge, Zhonghua Wu, Sérgio S. Funari and Yongfeng Men

      Article first published online: 22 MAR 2014 | DOI: 10.1002/polb.23474

      Thumbnail image of graphical abstract

      Pre-oriented polyethylene samples were drawn along different directions at different temperatures. For samples drawn along pre-stretching direction at a temperature of 30 °C, slippage of the micro-fibrils took place at moderate strain followed by macroscopic failure, whereas the fragmentation and recrystallization process was activated at higher temperatures, enabling a larger deformation. In the case of the 45° and 90° angle deformations the samples show much higher maxima achievable stress and strain due to suppression of micro-defect generation.

    4. Thermal analysis and FT-IR studies of adsorbed poly(ethylene-stat-vinyl acetate) on silica (pages 727–736)

      Madhubhashini Maddumaarachchi and Frank D. Blum

      Article first published online: 29 MAR 2014 | DOI: 10.1002/polb.23476

      Thumbnail image of graphical abstract

      The structure and thermal behavior of adsorbed poly(ethylene-stat-vinyl acetate) on fumed silica was studied using temperature-modulated differential scanning calorimetry and FT-IR spectroscopy. Carbonyls from vinyl acetate preferentially found their way to the silica surface over the ethylene segments. When based on the vinyl acetate content alone, the copolymers showed consistent bound fractions regardless of copolymer composition, except for the one with the smallest amount of vinyl acetate, which could be considered to be “carbonyl poor.”

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