Thermal Stability of Shear-Induced Precursors and Their Effect on the Crystalline Structure of β-Nucleated Isotactic Polypropylene
The thermal stability and lifetime of shear-induced precursors under various annealing temperatures, as well as the influence of their relaxation on the crystalline modification in β-nucleated isotactic polypropylene (iPP), are investigated using an ARES rheometer. The wide-angle X-ray diffraction r...
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| Main Author: | |
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| Format: | Article |
| Language: | English |
| Published: |
Wiley
2019-01-01
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| Series: | International Journal of Polymer Science |
| Online Access: | http://dx.doi.org/10.1155/2019/2950405 |
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| Summary: | The thermal stability and lifetime of shear-induced precursors under various annealing temperatures, as well as the influence of their relaxation on the crystalline modification in β-nucleated isotactic polypropylene (iPP), are investigated using an ARES rheometer. The wide-angle X-ray diffraction results show that the β-crystal content of sheared β-nucleated iPP samples gradually increases with thermal treatments. The relaxation of shear-induced precursors during annealing which caused the decrease of shear nuclei may restrain the counteraction effect between the shear flow and β-nucleation agent as well as result in the increase of β-crystal content. At the early stage of relaxation, the relaxation degree is closely related to the increase of β-crystals, for which the deeper relaxed shear-induced precursors result in the more restoration of β-crystals. However, when the relaxation degree exceeded a certain limitation, where the β-crystals reached the maximum, the relaxation of shear-induced precursors will no longer influence the crystal structure of β-nucleated iPP. |
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| ISSN: | 1687-9422 1687-9430 |