TY - JOUR
T1 - Flow-Induced Crystallization of PEEK
T2 - Isothermal Crystallization Kinetics and Lifetime of Flow-Induced Precursors during Isothermal Annealing
AU - Nazari, Behzad
AU - Rhoades, Alicyn Marie
AU - Schaake, Richard P.
AU - Colby, Ralph H.
PY - 2016/7/19
Y1 - 2016/7/19
N2 - 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.
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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U2 - 10.1021/acsmacrolett.6b00326
DO - 10.1021/acsmacrolett.6b00326
M3 - Article
AN - SCOPUS:84978971126
SN - 2161-1653
VL - 5
SP - 849
EP - 853
JO - ACS Macro Letters
JF - ACS Macro Letters
IS - 7
ER -