Flow-Induced Crystallization of PEEK: Isothermal Crystallization Kinetics and Lifetime of Flow-Induced Precursors during Isothermal Annealing

Behzad Nazari, Alicyn Marie Rhoades, Richard P. Schaake, Ralph H. Colby

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Abstract

The role of an interval of shear flow in promoting the flow-induced crystallization (FIC) for poly(ether ether ketone) PEEK was investigated by melt rheology and calorimetry. At 350 °C, just above the melting temperature of PEEK (Tm), a critical shear rate to initiate the formation of flow-induced precursors was found to coincide with the shear rate at which the Cox-Merz rule abruptly begins to fail. In cooling the sheared samples to 320 °C, FIC can be up to 25× faster than quiescent crystallization. Using rheology and differential scanning calorimetry, the stability of FIC-induced nuclei was investigated by annealing for various times at different temperatures above Tm. The persistence of shear-induced structures slightly above Tm, along with complete and rapid erasure of FIC-induced nuclei above the equilibrium melting temperature, suggests that FIC leads to thicker lamellae compared with the quiescently crystallized samples.

Original languageEnglish (US)
Pages (from-to)849-853
Number of pages5
JournalACS Macro Letters
Volume5
Issue number7
DOIs
StatePublished - Jul 19 2016

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All Science Journal Classification (ASJC) codes

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

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