Shear Flow-induced Crystallization of Poly(ether ether ketone)
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 of 1 s, the nucleation rate increases with the shear rate. At a constant shear rate of 20 s-1, the nucleation rate increases with the shearing time. For a constant strain (𝛾 = 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, which is found to be 8 – 10 nm3 which corresponds to 3 – 4 Kuhn segments for PEEK.
|Work Title||Shear Flow-induced Crystallization of Poly(ether ether ketone)|
|License||Public Domain Mark 1.0|
|Publisher Identifier (DOI)||
|Deposited||February 25, 2021 18:15|
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