Paper Number
TM20
Session
Rheometry: Advanced Techniques and Methods
Title
A filament stretching rheometer for in-situ X-ray experiment: Combining rheology and in-situ crystalline morphology characterization
Presentation Date and Time
October 22, 2019 (Tuesday) 1:30
Track / Room
Track 1 / Room 305A
Authors
- Pepe, Jessica (Eindhoven University of Technology, Mechanical Engineering, Polymer Technology Group)
- Cardinaels, Ruth (Eindhoven University of Technology, Mechanical Engineering, Polymer Technology Group)
- Peters, Gerrit (Eindhoven University of Technology, Mechanical Engineering, Polymer Technology Group)
- Anderson, Patrick D. (Eindhoven University of Technology, Mechanical Engineering, Polymer Technology Group)
Author and Affiliation Lines
Jessica Pepe, Ruth Cardinaels, Gerrit Peters, and Patrick D. Anderson
Mechanical Engineering, Polymer Technology Group, Eindhoven University of Technology, Eindhoven, Noord-Brabant 5600 MB, The Netherlands
Speaker / Presenter
Pepe, Jessica
Text of Abstract
During processing, polymers are subjected to various flow fields, consisting of both shear and extensional contributions. Whereas shear-induced crystallization has received substantial attention since decades, the effects of extensional flow on the nucleation, crystal structure formation and polymorphism are less known. This is mainly caused by the fact that suitable devices for the application of controlled uniaxial extensional flow combined with X-ray characterization are not available for the moment. We have designed and constructed a filament stretching rheometer that combines the possibility to perform in-situ X-ray experiments with a precisely controlled local uniaxial extensional flow. A homogeneous, uniaxial deformation of the sample with constant deformation rate is ensured thanks to a fast control scheme that drives the movement of the upper and bottom plate based on laser micrometer measurements of the smallest diameter[1]. The rheometer has a temperature-controlled oven with the ability to reach 250°C and to use an inert gas to avoid degradation of the sample. The oven has four ad-hoc windows: two glass windows for laser access and two kapton windows for X-ray access. The key feature of our in-house developed rheometer is the fixed location of the midfilament position, possible because of the simultaneous movement of the two end plates. This can be perfectly aligned with the laser micrometer and the incoming X-ray beam in a synchrotron radiation facility, allowing us to investigate structure and morphologies developed during extensional flow. The rheological response measured with our rheometer for a low density polyethylene (LDPE) is in agreement with the linear viscoelastic envelope and with the results obtained from commercial extensional rheometers. To demonstrate the capability of the instrument we have performed in-situ time resolved X-ray experiments on flow-induced crystallization of LDPE.
[1] J.M. Romám Marín et al., Journal of Non-Newtonian Fluid Mechanics 194 (2013) 14-22