Phase Transitions during Heating of Melt-Drawn Ultrahigh Molecular Weight Polyethylenes Having Different Molecular Characteristics

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• 作者：Masaki Kakiage ; Miho Sekiya ; Takeshi Yamanobe ; Tadashi Komoto ; Sono Sasaki ; Syozo Murakami ; Hiroki Uehara
• 刊名：Journal of Physical Chemistry B
• 出版年：2008
• 出版时间：May 1, 2008
• 年：2008
• 卷：112
• 期：17
• 页码：5311 - 5316
• 全文大小：503K
• 年卷期：v.112,no.17(May 1, 2008)
• ISSN：1520-5207

文摘

Changes in the crystalline structure during heating of melt-drawn ultrahigh molecular weight polyethylenes(UHMW-PEs) having different molecular characteristics were analyzed by in situ wide-angle X-ray diffractionmeasurements. A phase transition from the orthorhombic into the hexagonal phase was observed for all samples,but the perfection was enhanced and the possible temperature window for the hexagonal phase was greaterfor the sample containing only a higher molecular weight component. In contrast, an increase in retractivestress during heating was confirmed for the sample containing a lower molecular weight component, reflectingmelting of the folded-chain crystal (FCC). Differential scanning calorimetry and transmission electronmicroscopy revealed the dependency of the molecular characteristics of the sample on the resultantmorphologies. These results demonstrate that the existence of FCC determines both the quality and the widthof the temperature window for the hexagonal phase during heating of melt-drawn UHMW-PEs.