Thermal Conductivity in the Radial Direction of Deformed Polymer Fibers

Yanfu Lu, Jun Liu, Xu Xie, David G. Cahill

Research output: Contribution to journalArticlepeer-review


Thermal conductivity of polymer fibers in the axial direction has been extensively studied while thermal conductivity in the radial direction λ remains unknown. In this work, polymer fibers with different molecular arrangements (crystalline, liquid crystalline, and amorphous) were plastically deformed. λ was measured at engineering strains ϵ = 0.2-2.3 using time-domain thermoreflectance. λ decreases with increasing strains for polyethylene (PE) and poly(p-phenylene-2,6-benzobisoxazole) (PBO) fibers and is independent of strain for poly(methyl methacrylate) (PMMA) fibers. The extrapolated thermal conductivity at zero strain is λ0 ≈ 0.27 Wm-1 K-1 for crystalline PE, λ0 ≈ 0.29 Wm-1 K-1 for liquid crystalline PBO, and λ0 ≈ 0.18 Wm-1 K-1 for amorphous PMMA. λ of PE drops to λ ≈ 0.14 Wm-1 K-1 at ϵ = 1.9; λ of PBO drops to λ ≈ 0.12 Wm-1 K-1 at ϵ = 2.1. We attribute the decrease of λ with ϵ in crystalline and liquid crystalline fibers to structural disorder induced by plastic deformation. The combination of structural disorder and phonon focusing effects produces a thermal conductivity in deformed PE and PBO fibers that is lower than amorphous PMMA.

Original languageEnglish (US)
Pages (from-to)646-650
Number of pages5
JournalACS Macro Letters
Issue number6
StatePublished - Jun 21 2016

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry


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