Interdependencies between the evolution of amorphous and crystalline regions during isothermal cold crystallization of poly(ether-ether-ketone)
(1999) Macromolecules — Vol. 32, n° 5, p. 1582-1592 (1999)
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- We have studied the isothermal cold crystallization of poly(ether-ether-ketone) (PEEK) by atomic force microscopy, densitometry, differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and small- and wide-angle X-ray scattering (SAXS and WAXS), A two-stage process was clearly evidenced. The first stage results in the progressive consumption of free amorphous regions by growing spherulites. Lamellae grow in tightly packed bundles, with no evidence for a random insertion mechanism. DSC and DMA consistently show the progressive disappearance of the alpha(1) relaxation typical of the initially amorphous PEEK. Simultaneously, a new relaxation appears a few degrees higher (alpha(2) relaxation) and develops at the expense of alpha(1) relaxation. It corresponds to the formation of amorphous regions constrained by neighboring crystals. On the basis of a simple simulation, we show that the experimental data in this second stage of crystallization can be accounted for by a simple stack thickening process in which new lamellae are progressively added in parallel to previously formed lamellar stacks.
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Ivanov, D., Legras, R., & Jonas, A. (1999). Interdependencies between the evolution of amorphous and crystalline regions during isothermal cold crystallization of poly(ether-ether-ketone). Macromolecules, 32(5), 1582-1592. https://doi.org/10.1021/ma981220o (Original work published 1999)