The mechanism of fracture for entangled polymer liquids in extensional flow

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Abstract

In uniaxial extensional flow of entangled polymer liquids, different rupture modes may happen, including necking and fracture. Malkin andPetrie [1] proposed a ''master curve'' dividing the flow behavior into four zones based on the stretch rate: (I) Flow zone; (II) Transition zone; (III) Rubbery zone; and (IV) Glass-like zone. The master curve shows that steady extensional flow can only be reached in Zone I where thestretch rate is very slow, while rupture happens in Zones II-IV with faster stretch rate. Furthermore, Wang et al. [2-4] reported experimental datathat matches the master curve and suggested the mechanism of rupture in Zone III and IV is disentanglement and chain scission, respectively. In this work we measure two groups of entangled polystyrene solutions. In one group the samples have the same entanglement molecular weight (Me) but different number of entanglements (Z), and in the other group the samples have the same Z but different Me. We show that incontrolled filament stretching, steady extensional flow can be reached in Zones I-III, while fracture happens in Zone IV. The critical strain atfracture decreases with increasing stretch rate, which is in agreement with the master curve in Zone IV. However, with faster rate, a constant critical strain is observed, which is not shown in the original master curve. The value of the constant critical strain seems to be related to themaximum stretch ratio of the polymer chain (determined by Me), but not influenced by Z. The results are also compared with the critical strainof chemically crosslinked polymer networks.
Original languageEnglish
Publication date2017
Number of pages1
Publication statusPublished - 2017
EventThe Annual European Rheology Conference (AERC2017) - Copenhagen, Denmark
Duration: 3 Apr 20176 Apr 2017

Conference

ConferenceThe Annual European Rheology Conference (AERC2017)
CountryDenmark
CityCopenhagen
Period03/04/201706/04/2017

Cite this

Huang, Q., Yu, L., Skov, A. L., & Hassager, O. (2017). The mechanism of fracture for entangled polymer liquids in extensional flow. Abstract from The Annual European Rheology Conference (AERC2017), Copenhagen, Denmark.