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

Research output: Contribution to journalArticle

15 Citations (Scopus)

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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Isothermal annealing
Polyether ether ketones
Crystallization kinetics
Crystallization
Rheology
Shear deformation
Melting point
Calorimetry
Shear flow
polyetheretherketone
Differential scanning calorimetry
Annealing
Cooling

All Science Journal Classification (ASJC) codes

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

Cite this

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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.",
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Flow-Induced Crystallization of PEEK : Isothermal Crystallization Kinetics and Lifetime of Flow-Induced Precursors during Isothermal Annealing. / Nazari, Behzad; Rhoades, Alicyn Marie; Schaake, Richard P.; Colby, Ralph H.

In: ACS Macro Letters, Vol. 5, No. 7, 19.07.2016, p. 849-853.

Research output: Contribution to journalArticle

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T2 - Isothermal Crystallization Kinetics and Lifetime of Flow-Induced Precursors during Isothermal Annealing

AU - Nazari, Behzad

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AU - Colby, Ralph H.

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AB - 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.

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