Molecular dynamics simulations of crystal nucleation in entangled polymer melts under start-up shear conditions
Anwar, Muhammad; Graham, Richard S.
RICHARD GRAHAM email@example.com
Professor of Applied Mathematics
Understanding the flow induced crystallisation (FIC) process is necessary due to its technological relevance to polymer processing. Polymer crystallisation controls the morphology of semi-crystalline polymers and hence the properties of the end product. We perform molecular dynamics simulations of polymer melts consisting of sufficiently entangled linear chains under shear flow. We determine the Rouse relaxation time (τ R) for linear polymer chains using an established rheological model at different temperatures and fit the simulation data with the Arrhenius and Williams-Landel-Ferry (WLF) equations. We simulate the crystallisation induction times for different values of the Rouse Weissenberg number (W iR = ˙ γτ R) at different temperatures. We observe that the level of strain and stretch required to induce crystallisation increases with temperature. We find that the induction times follow a power law in shear rate and observe a more pronounced effect of flow rate for higher temperatures than at lower temperatures. Moreover, we determine that nucleation events occur relatively early in the shear transient and at a stretch value that is smaller than its steady state value. We also report the values of strain at which the occurrence of a nucleation event is most likely to happen.
|Journal Article Type||Article|
|Publication Date||Feb 27, 2019|
|Journal||The Journal of Chemical Physics|
|Peer Reviewed||Peer Reviewed|
|APA6 Citation||Anwar, M., & Graham, R. S. (2019). Molecular dynamics simulations of crystal nucleation in entangled polymer melts under start-up shear conditions. Journal of Rheology, 150(8), https://doi.org/10.1063/1.5082244|
|Keywords||Physical and Theoretical Chemistry; General Physics and Astronomy|
|Additional Information||The following article has been accepted by Journal of Rheology. After it is published, it will be found at 10.1063/1.5082244|
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