Hexagonal Phase of Polyethylene Fibers under High Pressure
Hexagonal Phase of Polyethylene Fibers under High Pressure
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高压下聚乙烯纤维的六方相
DOI：
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发表时间：
1991
期刊：
影响因子：
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通讯作者：
M. Yasuniwa
中科院分区：
文献类型：
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作者：
Shinsuke Tsubakihara;A. Nakamura;M. Yasuniwa
详细研究了受限超拉伸聚乙烯（PE）纤维（UDPF）的六方相。通过 DSC 和 X 射线测量在大气压下检查约束 UDPF 的熔化过程。六方相在受限 UDPF 熔化之前出现。显示六方相压力变化的相图是通过高达约 600 MPa 的高压 DTA 测定的。六方相的温度范围随着压力的增加而增加，并且与大约 300 MPa 以上的所谓“高压相”(HPP) 的温度范围一致。即，受约束的UDPF的六方相与HPP相同。通过高压 DTA 测定了三种 PE 样品、两种约束 UDPF 和一种由伸长链晶体组成的块状样品的相图，并将它们进行了相互比较。施加到这些 PE 样品上的约束力显着提高了 HPP 的熔化温度，而对从斜方相到 HPP 的转变温度几乎没有影响。通过约束力，UDPF的HPP即使在包括大气压力的低压区域也出现。
The hexagonal phase of a constrained ultra-drawn polyethylene (PE) fiber (UDPF) was studied in detail. The melting process of the constrained UDPF was examined at atmospheric pressure by DSC and X-ray measurement. The hexagonal phase appears prior to melting in the constrained UDPF. The phase diagram showing the pressure change of the hexagonal phase was determined by high pressure DTA up to about 600 MPa. The temperature range of the hexagonal phase increases with pressure and coincides with that of so-called “high pressure phase” (HPP) of it above about 300 MPa. That is, the hexagonal phase of the constrained UDPF is the same as HPP. The phase diagrams of three kinds of PE samples, two constrained UDPFs and a bulk sample composed of extended-chain crystals, determined by high pressure DTA, were compared with one another. The constraining force applied to these PE samples considerably raises the melting temperature of HPP, while it has almost no effect on the transition temperature from orthorhombic phase to HPP. By constraining force, HPP of UDPF appears even in the low pressure region that includes atmospheric pressure.