Abstract
By utilizing synchrotron rheo-WAXD (wide-angle X-ray diffraction) and rheo-SAXS (small-angle X-ray scattering) techniques, the nucleation and growth behavior of twisted kebabs from the shear-induced shish scaffold in entangled high-density polyethylene (HDPE) melts were investigated. The evolution of the (110) reflection intensity in WAXD at the early stages of crystallization could be described by a simplified Avrami equation, while the corresponding long period of kebabs determined by SAXS was found to decrease with time. The combined SAXS and WAXD results indicate that the kebab growth in sheared HDPE melts consists of two-dimensional geometry with thermal (sporadic) nucleation. The WAXD data clearly exhibited the transformations of (110) reflection from equatorial 2-arc to off-axis 4-arc and of (200) reflection from off-axis 4-arc to meridional 2-arc, which can be explained by the rotation of crystallographic a-axis around the b-axis during twisted kebab growth. This observation is also consistent with the orientation mode changes from 'Keller/Machin II' to 'intermediate' and then to 'Keller/Machin I'.
| Original language | English |
|---|---|
| Pages (from-to) | 4511-4519 |
| Number of pages | 9 |
| Journal | Polymer |
| Volume | 48 |
| Issue number | 15 |
| DOIs | |
| State | Published - Jul 13 2007 |
| Externally published | Yes |
Funding
We acknowledge the assistance of Drs. Igors Sics and Lixia Rong for the synchrotron SAXS and WAXD experimental setup. The financial support of this work was provided by the National Science Foundation (DMR-0405432).
| Funders | Funder number |
|---|---|
| National Science Foundation | DMR-0405432 |
Keywords
- Polyethylene
- Shear
- Shish-kebab