| People | Locations | Statistics |
|---|---|---|
| Naji, M. |
| |
| Motta, Antonella |
| |
| Aletan, Dirar |
| |
| Mohamed, Tarek |
| |
| Ertürk, Emre |
| |
| Taccardi, Nicola |
| |
| Kononenko, Denys |
| |
| Petrov, R. H. | Madrid |
|
| Alshaaer, Mazen | Brussels |
|
| Bih, L. |
| |
| Casati, R. |
| |
| Muller, Hermance |
| |
| Kočí, Jan | Prague |
|
| Šuljagić, Marija |
| |
| Kalteremidou, Kalliopi-Artemi | Brussels |
|
| Azam, Siraj |
| |
| Ospanova, Alyiya |
| |
| Blanpain, Bart |
| |
| Ali, M. A. |
| |
| Popa, V. |
| |
| Rančić, M. |
| |
| Ollier, Nadège |
| |
| Azevedo, Nuno Monteiro |
| |
| Landes, Michael |
| |
| Rignanese, Gian-Marco |
|
Rhoades, Alicyn M.
in Cooperation with on an Cooperation-Score of 37%
Topics
Publications (2/2 displayed)
Places of action
| Organizations | Location | People |
|---|
article
Shear Flow-Induced Crystallization of Poly(ether ether ketone)
Abstract
<p>When a semicrystalline polymer melt is subjected to sufficient flow before crystallization, the nucleation rate is accelerated. In this study, the degree of acceleration is investigated with a commercial poly(ether ether ketone), using a rotational rheometer. With a constant shearing time (t<sub>s</sub> = 1 s), the nucleation rate increases with the shear rate (10 s<sup>-1</sup> < γ&dot; < 200 s<sup>-1</sup>). At a constant shear rate (γ&dot; = 20 s<sup>-1</sup>), the nucleation rate increases with the shearing time (1 s < t<sub>s</sub> < 15 s). For a constant strain (γ= γ&dot;t<sub>s</sub> = 300), high shear rates with short shearing times enhance the nucleation rate more than low shear rates with long shearing times. The specific work (W = σγ, where σ is the shear stress) reduces all nucleation times to a common curve. A flow-induced nucleation model is suggested based on the entropy reduction model of Flory and the isothermal nucleation model of Hoffman and Lauritzen. A key ingredient is the critical volume of the nucleus, found to be 8-10 nm<sup>3</sup>, which corresponds to 3-4 Kuhn segments for PEEK.</p>