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Effects of Solid-State Stretching on Microstructure Evolution and Physical Properties of Isotactic Polypropylene Sheets
The microstructure evolution of an isotactic polypropylene (iPP) sheet during solid-state stretching was studied. The transition of the spherulites—cylindrites was evaluated using in-situ two-dimensional wide-angle and small-angle X-ray scattering methods. The crystallinity of stretched iPP sheets w...
Autores principales: | , , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
MDPI
2019
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6523338/ https://www.ncbi.nlm.nih.gov/pubmed/30960603 http://dx.doi.org/10.3390/polym11040618 |
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author | Ji, Huajian Zhou, Xulin Chen, Xin Zhao, Haili Wang, Yu Zhu, Huihao Shan, Xiliang Sha, Jin Ma, Yulu Xie, Linsheng |
author_facet | Ji, Huajian Zhou, Xulin Chen, Xin Zhao, Haili Wang, Yu Zhu, Huihao Shan, Xiliang Sha, Jin Ma, Yulu Xie, Linsheng |
author_sort | Ji, Huajian |
collection | PubMed |
description | The microstructure evolution of an isotactic polypropylene (iPP) sheet during solid-state stretching was studied. The transition of the spherulites—cylindrites was evaluated using in-situ two-dimensional wide-angle and small-angle X-ray scattering methods. The crystallinity of stretched iPP sheets was characterized by differential scanning calorimetry. The crystal morphology was observed by means of scanning electron microscopy. It was found that the differences of crystal microstructure of the iPP sheet depended on the stretching strain, which promoted the orientation of molecular chains. Amorphous molecular chains in the spherulites oriented and formed into a mesophase near the yield point, and the partially ordered mesophase was further stretched to form an oriented cylindrite structure after the yield point. The highest relative content of cylindrites appeared at 15% strain. Notably, as the amorphous phase embedded into the lamellae layer, the crystal size decreased with the increase of strain, which indicated that the crystallinity of the stretched iPP sheet was much higher than that of unstretched iPP sheet. The induced cylindrites structure played a more important role in improving the mechanical properties and heat resistance of iPP sheets. Compared with the unstretched iPP sheets, the tensile strength increased by 28%, the notch impact toughness significantly increased by 78%, and the vicat softening point increased from 104 to 112 °C. |
format | Online Article Text |
id | pubmed-6523338 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2019 |
publisher | MDPI |
record_format | MEDLINE/PubMed |
spelling | pubmed-65233382019-06-03 Effects of Solid-State Stretching on Microstructure Evolution and Physical Properties of Isotactic Polypropylene Sheets Ji, Huajian Zhou, Xulin Chen, Xin Zhao, Haili Wang, Yu Zhu, Huihao Shan, Xiliang Sha, Jin Ma, Yulu Xie, Linsheng Polymers (Basel) Article The microstructure evolution of an isotactic polypropylene (iPP) sheet during solid-state stretching was studied. The transition of the spherulites—cylindrites was evaluated using in-situ two-dimensional wide-angle and small-angle X-ray scattering methods. The crystallinity of stretched iPP sheets was characterized by differential scanning calorimetry. The crystal morphology was observed by means of scanning electron microscopy. It was found that the differences of crystal microstructure of the iPP sheet depended on the stretching strain, which promoted the orientation of molecular chains. Amorphous molecular chains in the spherulites oriented and formed into a mesophase near the yield point, and the partially ordered mesophase was further stretched to form an oriented cylindrite structure after the yield point. The highest relative content of cylindrites appeared at 15% strain. Notably, as the amorphous phase embedded into the lamellae layer, the crystal size decreased with the increase of strain, which indicated that the crystallinity of the stretched iPP sheet was much higher than that of unstretched iPP sheet. The induced cylindrites structure played a more important role in improving the mechanical properties and heat resistance of iPP sheets. Compared with the unstretched iPP sheets, the tensile strength increased by 28%, the notch impact toughness significantly increased by 78%, and the vicat softening point increased from 104 to 112 °C. MDPI 2019-04-03 /pmc/articles/PMC6523338/ /pubmed/30960603 http://dx.doi.org/10.3390/polym11040618 Text en © 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). |
spellingShingle | Article Ji, Huajian Zhou, Xulin Chen, Xin Zhao, Haili Wang, Yu Zhu, Huihao Shan, Xiliang Sha, Jin Ma, Yulu Xie, Linsheng Effects of Solid-State Stretching on Microstructure Evolution and Physical Properties of Isotactic Polypropylene Sheets |
title | Effects of Solid-State Stretching on Microstructure Evolution and Physical Properties of Isotactic Polypropylene Sheets |
title_full | Effects of Solid-State Stretching on Microstructure Evolution and Physical Properties of Isotactic Polypropylene Sheets |
title_fullStr | Effects of Solid-State Stretching on Microstructure Evolution and Physical Properties of Isotactic Polypropylene Sheets |
title_full_unstemmed | Effects of Solid-State Stretching on Microstructure Evolution and Physical Properties of Isotactic Polypropylene Sheets |
title_short | Effects of Solid-State Stretching on Microstructure Evolution and Physical Properties of Isotactic Polypropylene Sheets |
title_sort | effects of solid-state stretching on microstructure evolution and physical properties of isotactic polypropylene sheets |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6523338/ https://www.ncbi.nlm.nih.gov/pubmed/30960603 http://dx.doi.org/10.3390/polym11040618 |
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