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Unexpected shish-kebab structure in a sheared polyethylene melt
Benjamin S Hsiao1, Ling Yang, Rajesh H Somani
1Department of Chemistry, State University of New York at Stony Brook, Stony Brook, NY 11794-3400, USA. bhsiao@notes.cc.sunysb.edu
Physical Review Letters
|May 21, 2005
Summary
Researchers discovered a novel multiple shish-kebab structure in polyethylene blends. This unexpected finding in ultrahigh molecular weight polyethylene (UHMWPE) offers new insights into polymer crystallization processes.
Area of Science:
- Polymer Science
- Materials Science
- Crystallization
Background:
- Polyethylene (PE) blends are widely used in various applications.
- Understanding the crystallization behavior of polymers is crucial for material property control.
- Previous studies on PE blends have not reported the observed shish-kebab structure.
Purpose of the Study:
- To investigate the microstructural morphology of a specific polyethylene blend.
- To elucidate the formation mechanism of an unexpected crystalline structure.
- To provide a detailed analysis of the shish-kebab structure in polymer blends.
Main Methods:
- Solvent-extracted sheared polyethylene blend preparation.
- Scanning electron microscopy (SEM) for morphological analysis.
- Synchrotron X-ray scattering for structural elucidation.
Main Results:
- Observation of an unprecedented shish-kebab structure with multiple shish.
- Identification of ultrahigh molecular weight polyethylene (UHMWPE) as the crystallizing component within a noncrystallizing PE matrix.
- Correlation of multiple shish formation with the coil-stretch transition of UHMWPE chains.
Conclusions:
- The study reveals a novel multiple shish-kebab morphology in PE blends.
- Multiple shish structures originate from stretched UHMWPE chain segments.
- Coiled chain segments form the kebab structures, driven by a diffusion-controlled crystallization process.