This work concerns extension induced crystallization of a commercial high density polyethylene above the equilibrium melting temperature. We compare the nonlinear response during uniaxial elongation to the morphology obtained in the quenched fibers after cessation of the flow at a Hencky strain of 5. At 12 °C above the melting temperature, the samples undergo brittle fracture. Samples stretched at 2 and 6 °C above the melting temperature remain intact throughout the entire course of deformation and exhibit a strain hardening behavior that does not follow time temperature superposition. We propose that stabilization of the filament at lower temperatures, as well as the failure of time temperature superposition, is caused by flow-induced nucleation and growth of shish structures oriented along the flow direction. Further justification is obtained from small-angle X-ray scattering performed on the quenched filament showing an increased formation of shish with an increase in the deformation rate. We find the critical Hencky strain for the onset of the shish formation to be between 0 and 0.6, which is significantly lower than the values reported in the existing literature. We model the influence of shish nucleation on the rheological response in an extension using the hierarchical multimode stress function, which is modified to include the stretched network assumption.
Skip Nav Destination
Flow induced crystallization prevents melt fracture of HDPE in uniaxial extensional flow
Article navigation
July 2018
Research Article|
July 01 2018
Flow induced crystallization prevents melt fracture of HDPE in uniaxial extensional flow
Special Collection:
Flow-Induced Crystallization
Sara L. Wingstrand;
Sara L. Wingstrand
1
Department of Chemical and Biochemcial Engineering, Danish Polymer Center, Technical University of Denmark
, DK-2800 Kgs. Lyngby, Denmark
Search for other works by this author on:
Ole Hassager;
Ole Hassager
a)
1
Department of Chemical and Biochemcial Engineering, Danish Polymer Center, Technical University of Denmark
, DK-2800 Kgs. Lyngby, Denmark
a)Author to whom correspondence should be addressed; electronic mail: oh@kt.dtu.dk
Search for other works by this author on:
Daniele Parisi;
Daniele Parisi
b)
2
Institute of Electronic Structure and Laser, FORTH
, Heraklion 71110, Crete, Greece
Search for other works by this author on:
Anine L. Borger;
Anine L. Borger
3
Niels Bohr Institute, X-ray and Neutron Science, University of Copenhagen
, DK-2100 København Ø, Denmark
Search for other works by this author on:
Kell Mortensen
Kell Mortensen
3
Niels Bohr Institute, X-ray and Neutron Science, University of Copenhagen
, DK-2100 København Ø, Denmark
Search for other works by this author on:
b)
Present address: Department of Materials Science and Technology, University of Crete, Heraklion 71003, Crete, Greece.
a)Author to whom correspondence should be addressed; electronic mail: oh@kt.dtu.dk
J. Rheol. 62, 1051–1060 (2018)
Article history
Received:
May 03 2018
Accepted:
June 18 2018
Citation
Sara L. Wingstrand, Ole Hassager, Daniele Parisi, Anine L. Borger, Kell Mortensen; Flow induced crystallization prevents melt fracture of HDPE in uniaxial extensional flow. J. Rheol. 1 July 2018; 62 (4): 1051–1060. https://doi.org/10.1122/1.5038393
Download citation file:
Sign in
Don't already have an account? Register
Sign In
You could not be signed in. Please check your credentials and make sure you have an active account and try again.
Sign in via your Institution
Sign in via your InstitutionPay-Per-View Access
$40.00