Journal of Polymer Science Part B: Polymer Physics

Cover image for Vol. 49 Issue 21

1 November 2011

Volume 49, Issue 21

Pages i–ii, 1493–1562

  1. Cover Image

    1. Top of page
    2. Cover Image
    3. Communications
    4. Full Papers
    1. You have free access to this content
      Cover Image, Volume 49, Issue 21 (pages i–ii)

      Version of Record online: 23 SEP 2011 | DOI: 10.1002/polb.22370

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      One popular approach for improving conductivity in solid polymer electrolytes (SPEs) for lithium-ion batteries is the addition of metal oxide nanoparticles. Although nanoparticles modestly improve conductivity, the improvement can vary depending on the conditions under which the samples are handled and tested. The cover depicts a rendering of the microstructure expected at the eutectic concentration when a nanoparticle-filled SPE of polyethylene oxide (PEO) and LiClO4 is exposed to humidity. At this lithium concentration, the formation of two phases is energetically favored, and nanoparticles may segregate to the lithium-poor phase. Read more about this research from Susan Fullerton-Shirey, Lalitha Ganapatibhotla, Wenjin Shi, and Janna Maranas on page 1496 of this issue.

  2. Communications

    1. Top of page
    2. Cover Image
    3. Communications
    4. Full Papers
    1. Computational analysis of bending strain in single chains of β-PVDF (pages 1493–1495)

      Elana A. Viola and William B. Euler

      Version of Record online: 31 AUG 2011 | DOI: 10.1002/polb.22348

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      One of the most heavily studied electroactive polymers is poly(vinylidene difluoride) (PVDF), as it—and related polymers—find uses in sensor arrays, energy harvesting and storage, and acoustical/optical communications. For these applications, stretching motions of the polymer chains are exploited, but for some applications, a more appropriate configuration would use chain bending instead. In this communication, the energy changes associated with bending of PVDF chains and the potential to use bending for energy harvesting are explored.

  3. Full Papers

    1. Top of page
    2. Cover Image
    3. Communications
    4. Full Papers
    1. Influence of thermal history and humidity on the ionic conductivity of nanoparticle-filled solid polymer electrolytes (pages 1496–1505)

      Susan K. Fullerton-Shirey, Lalitha V. N. R. Ganapatibhotla, Wenjin Shi and Janna K. Maranas

      Version of Record online: 9 AUG 2011 | DOI: 10.1002/polb.22330

      Thumbnail image of graphical abstract

      It is well known that oxide nanoparticles improve conductivity in solid polymer electrolytes. This work shows that the extent of improvement depends on variables such as thermal history and water content. Although water cannot be present in the electrolyte of a functioning battery, the conditions under which SPEs are often studied involve exposure to various levels of humidity. The handling and testing conditions have important consequences for evaluating the influence of nanoparticle fillers on SPE performance.

    2. Aspects of fatigue failure mechanisms in polymer fuel cell membranes (pages 1506–1517)

      Ahmet Kusoglu, Michael H. Santare and Anette M. Karlsson

      Version of Record online: 17 AUG 2011 | DOI: 10.1002/polb.22336

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      The swelling-driven fatigue behavior of membranes in a polymer electrolyte fuel cell during relative humidity (RH) cycling is investigated numerically. When the membrane is subjected to humidity changes, stresses develop in the plane of the membrane. In general, higher RH (or swelling) amplitude results in larger stress amplitudes, and tensile stresses are more critical for forming cavities in the membrane, which may eventually lead to craze formation and shorter lifetime, that is, fewer cycles to failure.

    3. A critical local energy release rate criterion for fatigue fracture of elastomers (pages 1518–1524)

      Samy Mzabi, Daniel Berghezan, Stéphane Roux, Francois Hild and Costantino Creton

      Version of Record online: 7 SEP 2011 | DOI: 10.1002/polb.22338

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      Models relating the linear viscoelastic properties of elastomers to their fracture behavior often fail to estimate fracture energy because they ignore the large strain region near the crack tip. Digital Image Correlation can characterize the full strain field near the tip of a crack, showing that fracture resistance of filled elastomers is controlled by their ability to relax high stresses and reduce strains at the crack tip, rather than by the intrinsic strength of chemical bonds.

    4. Modeling highly branched structures: Description of the solution structures of dendrimers, polyglycerol, and glycogen (pages 1525–1538)

      Dominik Konkolewicz, Sébastien Perrier, David Stapleton and Angus Gray-Weale

      Version of Record online: 29 AUG 2011 | DOI: 10.1002/polb.22340

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      Random Branching Theory is used to characterize the solution structure of various hyperbranched polymers. The simple model successfully describes the structure of both natural and synthetic highly branched macromolecules. While designed for randomly branched polymers, it is shown that this approach can be also extended to the study of the structureC of regularly branched dendrimers.

    5. Physical properties of diblock methylcellulose derivatives with regioselective functionalization patterns: First direct evidence that a sequence of 2,3,6-tri-O-methyl-glucopyranosyl units causes thermoreversible gelation of methylcellulose (pages 1539–1546)

      Atsushi Nakagawa, Dominik Fenn, Andreas Koschella, Thomas Heinze and Hiroshi Kamitakahara

      Version of Record online: 31 AUG 2011 | DOI: 10.1002/polb.22343

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      The unique thermoreversible gelation of methylcellulose (MC) is an important asset in many end-use applications. To be able to tune the properties of the gel, it is important to clarify the nature and structure of the reversible crosslinks responsible of the solution behavior of the material. Here a combination of optical, mechanic and calorimetric techniques are used to identify and discuss those essential structural factors that govern gelation of MC.

    6. Influence of polymer particle size on the percolation threshold of electrically conductive latex-based composites (pages 1547–1554)

      Gregory P. Moriarty, James H. Whittemore, Katherine Ann Sun, James W. Rawlins and Jaime C. Grunlan

      Version of Record online: 27 AUG 2011 | DOI: 10.1002/polb.22344

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      The ability to tailor percolation threshold with latex particle size provides an important tool for manipulating electrical and mechanical properties of polymer nanocomposites. Such control is achieved here in the case of carbon black-filled polymer composites. The percolation threshold decreases as the latex particle size increases. This behavior is attributed to greater excluded volume by the polymer, with increasing particle size, which in turns reduces the amount of carbon black needed to create conductive pathways.

    7. Decoupling the effects of crystallinity and orientation on the shear piezoelectricity of polylactic acid (pages 1555–1562)

      Conrad S. Lovell, James M. Fitz-Gerald and Cheol Park

      Version of Record online: 7 SEP 2011 | DOI: 10.1002/polb.22345

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      Shear piezoelectricity is linearly proportional to the product of polymer crystallinity and orientation. The understanding of this phenomenon has been however so far incomplete, as orientation is usually used to alter crystallinity. Here, the two parameters are decoupled and can be controlled independently through drawing and annealing steps. It is shown that poly(lactic acid) shear piezoelectricity possesses a stronger relationship with the product of crystallinity and orientation than either of these parameters individually.

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