The effect of molecular weight and crystallite structure on yielding in ethylene copolymers
| Autor: | Leo Mandelkern, Rufina G. Alamo, J. T. Graham |
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| Rok vydání: | 1997 |
| Předmět: |
Yield (engineering)
Materials science Polymers and Plastics Analytical chemistry Polyethylene Condensed Matter Physics law.invention chemistry.chemical_compound Crystallinity chemistry law Transmission electron microscopy Polymer chemistry Materials Chemistry Lamellar structure Orthorhombic crystal system sense organs Crystallite Physical and Theoretical Chemistry Crystallization |
| Zdroj: | Journal of Polymer Science Part B: Polymer Physics. 35:213-223 |
| ISSN: | 1099-0488 0887-6266 |
| DOI: | 10.1002/(sici)1099-0488(19970130)35:2<213::aid-polb2>3.0.co;2-t |
| Popis: | Nominal stress-strain curves of a series of random ethylene-hexene copolymers having narrow composition and most probable molecular weight distributions were investigated. A series of such molecular weight copolymers with a constant concentration of branches were crystallized under a variety of conditions. In each molecular weight series the level of crystallinity was approximately constant. Particular attention was focused on the yield region and the nature of the yielding process. It was found, quite surprisingly, that the yield stress was not solely dependent on the crystallinity level. Moreover, the shape of the force-elongation curve in the yield region was very dependent on the molecular weight and the crystallization mode. These changes in yielding correlated quite well with the overall crystallite structure that was characterized by thin section transmission electron microscopy. The orthorhombic unit cell of polyethylene was maintained in all the samples despite the changes that occurred in the overall crystallite structure. © 1997 John Wiley & Sons, Inc. |
| Databáze: | OpenAIRE |
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