Journal of Polymer Science Part B: Polymer Physics

Cover image for Vol. 50 Issue 14

15 July 2012

Volume 50, Issue 14

Pages i–iv, 945–1012

  1. Cover Image

    1. Top of page
    2. Cover Image
    3. Reviews
    4. Full Papers
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      Cover Image, Volume 50, Issue 14 (pages i–ii)

      Version of Record online: 2 JUN 2012 | DOI: 10.1002/polb.23108

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      Piezoresistive metal-insulator composites are good candidates as functional materials for tactile sensor applications. Huge electrical resistance variations upon compressive or tensile stress has been achieved in a composite material based on nickel conductive filler in a polydimethylsiloxane (PDMS) insulating matrix. The conduction mechanism, enhanced by the spiky nanostructured morphology of the filler particles inside the composite, is based on a quantum tunneling effect as confirmed by theoretical models. An exhaustive investigation on the mechanical, electrical and thermal properties of the piezoresistive composite is presented by Stefano Stassi and Giancarlo Canavese on page 984.

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      Inside Cover, Volume 50, Issue 14 (pages iii–iv)

      Version of Record online: 2 JUN 2012 | DOI: 10.1002/polb.23109

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      Carbon nanotubes (CNTs), when sufficiently dispersed in a polymer matrix, offer exceptional mechanical properties as reinforcement fillers in nanocomposite materials. In addition to homogeneous dispersion, optimization of the interfacial bonding between both contacting phases is essential for CNT incorporation to reach full potential. In the study by Noa Lachman, Yifat Harel, Adam Green, Noa Iuster, Jean-Paul Lellouche, and H. Daniel Wagner on page 957, multiwalled CNTs of various diameters, both untreated pristine and polycarboxylated, are dispersed at equal weight percentage in an epoxy matrix, and resulting fracture toughnesses are measured. An optimal diameter exists depending on CNT thickness and surface treatment.

  2. Reviews

    1. Top of page
    2. Cover Image
    3. Reviews
    4. Full Papers
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      Novel approaches to flexible visible transparent hybrid films for ultraviolet protection (pages 945–956)

      Mauricio E. Calvo, José R. Castro Smirnov and Hernán Míguez

      Version of Record online: 6 MAY 2012 | DOI: 10.1002/polb.23087

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      In this review, the different approaches taken to obtain flexible and transparent films that block ultraviolet radiation based on the use of hybrid materials are covered. The synthetic pathways that lead to films that can shield against UV radiation either by absorption or by interference are described.

  3. Full Papers

    1. Top of page
    2. Cover Image
    3. Reviews
    4. Full Papers
    1. Effect of scale and surface chemistry on the mechanical properties of carbon nanotubes-based composites (pages 957–962)

      Noa Lachman, Yifat Harel, Adam Green, Noa Iuster, Jean-Paul Lellouche and H. Daniel Wagner

      Version of Record online: 28 APR 2012 | DOI: 10.1002/polb.23085

      Thumbnail image of graphical abstract

      Carbon nanotubes (CNTs), when sufficiently dispersed in a polymer matrix, offer exceptional mechanical properties as reinforcement fillers in nanocomposite materials. In addition to homogeneous dispersion, optimization of the interfacial bonding between both contacting phases is essential for CNT incorporation to reach full potential. In this study, multiwalled CNTs of various diameters, both untreated pristine and polycarboxylated, were dispersed at equal weight percentage in an epoxy matrix, and resulting fracture toughnesses have been measured. An optimal diameter exists depending on CNT thickness and surface treatment.

    2. Influence of multiwall carbon nanotubes on morphological and structural changes during UV irradiation of syndiotactic polypropylene films (pages 963–975)

      L. Guadagno, M. Raimondo, C. Naddeo, A. Di Bartolomeo and K. Lafdi

      Version of Record online: 25 MAY 2012 | DOI: 10.1002/polb.23093

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      The study of the degradation by UV irradiation of polymeric composites is necessary to understand the nanofiller influence on durability of the material. Investigated here is the effect of UV irradiation on the morphology and structure of syndiotactic polypropylene both for pure films and those filled with multiwall carbon nanotubes (MWCNTs). UV treatment of pure (unfilled) polypropylene films causes a complex structural reorganization of chain conformations. A strong stabilizing effect against UV irradiation is achieved by incorporating MWCNTs in the same polypropylene films (filled samples).

    3. Why does the electrical conductivity in PEDOT:PSS decrease with PSS content? A study combining thermoelectric measurements with impedance spectroscopy (pages 976–983)

      Thomas Stöcker, Anna Köhler and Ralf Moos

      Version of Record online: 14 MAY 2012 | DOI: 10.1002/polb.23089

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      The conductivity of a blend of poly(3,4-ethylenedioxythiophene) (PEDOT) doped with poly(4-styrenesulfonic acid) (PSS) varies strongly with PSS content. In this investigation, measurements of the Seebeck coefficient are used to show that this is not associated with changes in the doping level. Rather, charge carrier transport is found to proceed by percolation between high-mobility PEDOT:PSS grains in a low-mobility PSS matrix, as demonstrated using a generalized effective media theory to model the electrical conductivity.

    4. Spiky nanostructured metal particles as filler of polymeric composites showing tunable electrical conductivity (pages 984–992)

      Stefano Stassi and Giancarlo Canavese

      Version of Record online: 6 MAY 2012 | DOI: 10.1002/polb.23091

      Thumbnail image of graphical abstract

      A huge piezoresistive response upon compressive or tensile stress is achieved in a composite material based on nickel conductive filler in a polydimethylsiloxane (PDMS) insulating matrix. The conduction mechanism, enhanced by the spiky nanostructured morphology of the particles inside the composite, is based on a quantum tunneling effect as confirmed by theoretical models. The huge variation in resistance upon a small deformation of the composite material makes it a good candidate for sensor applications.

    5. Multilayered polycarbonate/poly(vinylidene fluoride-co-hexafluoropropylene) for high energy density capacitors with enhanced lifetime (pages 993–1003)

      Zheng Zhou, Matt Mackey, Joel Carr, Lei Zhu, Lionel Flandin and Eric Baer

      Version of Record online: 14 MAY 2012 | DOI: 10.1002/polb.23094

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      Layering dielectric films of two different thermoplastics, namely poly(vinylidene fluoride-co-hexafluoropropylene) and bisphenol A polycarbonate (PC), enhances the dielectric lifetime by two orders of magnitude relative to simple blend films of the same two components. “Forced assembly” multilayer coextrusion was used to produce alternately layered films. PC layers act as charge barrier layers which can slow charge migration and reduce impact ionization in the film. Also, the layered structure can deflect the fracture propagation pathway across the film thickness.

    6. Large-scale aligned fiber mats prepared by salt-induced pulse electrospinning (pages 1004–1012)

      Quanchao Zhang, Lihua Wang, Zhimei Wei, Xiaojun Wang, Shengru Long and Jie Yang

      Version of Record online: 14 MAY 2012 | DOI: 10.1002/polb.23096

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      Aligned electrospun polymer fibers can be used as filtration membranes, directional optical components, and tissue scaffolds, but the method of alignment can limit any practical applications due to an inability to produce mats of usable size. In this work, a new aligned fiber formation method via salt-induced pulse electrospinning is reported. By electrospinning a salted solution in a humid environment, the traditionally continuous electrospinning process changed into a pulsed process. Using this method, large-scale aligned fiber mats can be prepared.

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