Abstract
The formation of initial crystallization precursor induced by flow was investigated by synchrotron-based wide- and small-angle X-ray scattering techniques (WAXS/SAXS), using polymer blends consisting of high molecular weight isotactic polypropylene (HMW-iPP) and low molecular weight linear low density polyethylene (LMW-LLDPE) as model systems. LMW-LLDPE, the dominant component, served as the amorphous matrix. Crystallization behavior of the blends with three different HMW-iPP concentrations, i.e., 3, 6 and 9 wt%, were examined at temperatures higher than the blends' cloud points, in a time-resolved manner. It was found that the formation of a flow-induced precursor of crystallization was strongly influenced by the concentration of HMW-iPP in the blends. The blend with low HMW-iPP content (3 wt%) was not able to form a shear-induced crystalline structure. As the concentration of HMW-iPP increased, crystallization kinetics, crystallinity, and lamellar orientation were greatly enhanced.
| Original language | English |
|---|---|
| Pages (from-to) | 1425-1431 |
| Number of pages | 7 |
| Journal | Polymer |
| Volume | 54 |
| Issue number | 4 |
| DOIs | |
| State | Published - Feb 18 2013 |
| Externally published | Yes |
Funding
We acknowledge the assistance of Drs. L. Rong, J. Zhu and R. Somani for experimental setup. The financial support was provided by the National Science Foundation ( DMR-0405432 ) and the Department of Energy .
Keywords
- Flow-induced crystallization
- Polypropylene
- WAXS/SAXS