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Going to Extremes Meeting the Emerging Demand for Durable Polymer Matrix Composites (2005) / Chapter Skim
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Appendix C Why Polymers Are More Susceptible Than Other Materials to Environmental Damage
Pages 51-53

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From page 51...
... In other words, a polymer at room temperature displays physical characteristics that are relatively speaking much closer to glass transition behavior than an inorganic glass at room temperature. In the case of inorganic silicate glasses, the strong intermolecular forces lead to glass transition temperatures that are typically many hundreds of degrees higher than typical glass transition 1 The London dispersion force is an attractive force between atoms or molecules caused by the numerous transient dipoles resulting from electronic superposition.
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From page 52...
... This is analogous to hightemperature behavior in a metal except that the polymer may actually be at room temperature! This further illustrates the concept that the sensitivity of polymer matrix composites to their environment is largely a result of the weak intermolecular forces and the resulting high homologous temperatures.2 To summarize, the weak intermolecular forces that are responsible for the unique physical properties of polymers (in the present context, most notably their low densities and viscoelastic behavior, including rate dependence, toughness, and ductility)
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From page 53...
... Consequently, deconvolution of observed environmental phenomena into component matrix and interface phenomena may be severely complicated. Finally, the dominant role played by conformational entropy in the structure and properties of high polymers leads to a huge multiplicity of morphological states having small differences in internal energy but huge differences in conformational entropy, as exemplified by heat-activated shrink wrap used in the electronics industry.
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Key Terms

  • weak intermolecular
  • intermolecular forces
  • homologous temperatures
  • conformational entropy
  • intermolecular bonds

  • transition temperature
  • polymer matrix
  • transition temperatures
  • entropy changes
  • internal energy

  • polymers leads
  • energy density
  • homologous temperature
  • muscle contraction
  • strong function

  • matrix composites
  • entropy state
  • london dispersion
  • chain conformation
  • hydrogen bonds

  • morphological states
  • polymers display
  • weak bonds
  • greatly reduced
  • diffusing species

  • semicrystalline polymers
  • low densities
  • physical characteristics
  • effectively replace
  • noncovalently bound


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