Title
Influence of shear flow on the specific volume and the crystalline morphology of isotactic polypropylene
Author
TNO Industrie en Techniek
van der Beek, M.H.E.
Peters, G.W.M.
Meijer, H.E.H.
Publication year
2006
Abstract
The influence of shear flow on the temperature evolution of the specific volume and the crystalline morphology of two iPP's, differing in weight-averaged molar mass Mw, was investigated at nonisofhermal conditions and elevated pressures, using a custom-designed dilatometer. These conditions are typically in the range of conditions as experienced during polymer processing. A pronounced influence of flow on the temperature marking the transition in specific volume and the rate of transition could be observed. In general, this influence increased with increasing shear rate, decreasing temperature where flow was applied, increasing pressure, and increasing weight-averaged molar mass Mw of the polymer. Although the degree of orientation and the overall structure of the resulting crystalline morphology were greatly affected by the flow, the resulting specific volume was only little affected by the thermomechanical conditions presently investigated. Finally, when flow was applied at sufficiently high temperature, in some cases the polymer was able to fully erase the effect of flow. This is attributed to remelting of the flow-induced crystalline structures.
Subject
Crystal structure
Crystallization
Molecular weight
Morphology
Polypropylenes
Crystalline morphology
Isotactic polypropylene
Temperature marking
Shear flow
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http://resolver.tudelft.nl/uuid:3b89797b-8704-4bf1-aa22-a901dde6f047
DOI
https://doi.org/10.1021/ma051914e
TNO identifier
239174
Publisher
ACS
ISSN
0024-9297
Source
Macromolecules, 39 (39), 1805-1814
Document type
article