Structural transformation of ultra-high modulus and molecular weight polyethylene fibers by high-temperature wide-angle X-ray diffraction
Structural transformation of ultra-high modulus and molecular weight polyethylene fibers by high-temperature wide-angle X-ray diffraction
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DOI：
10.1002/(sici)1099-0488(199703)35:4
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发表时间：
1997-03
期刊：
影响因子：
--
通讯作者：
Y. Hsieh;Xiaoping Hu
中科院分区：
文献类型：
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作者：
Y. Hsieh;Xiaoping Hu
室温下超高模量和分子量聚乙烯（UHMWPE）纤维的广角X射线衍射（WAXD）显示出主要的正交结构，具有痕量的非正交晶体和非常低的非晶含量。计算得到的正交晶体的晶胞尺寸a和B分别为7.36（±0.04）A和4.89（±0.04）A。垂直于正交110和200反射面的表观微晶尺寸分别为169.8和143.4 A。垂直于非正交010反射的微晶尺寸为149.4 A。晶体密度计算为1.02 g/cc。随着温度的升高，在a方向上的热膨胀系数远高于在B方向上的热膨胀系数，这解释了从正交晶体到假六方晶体的结构转变。在高温X射线衍射（HTWAXD）扫描期间，当被加热时，沿纤维轴的张力沿着已经显示出从正交晶形式到单斜晶形式的增强的结构转变。在HTWAXD中，在轴向拉伸或退火条件下，在UHMWPE纤维上没有观察到从正交晶形式到假六方晶相的结构转变。John Wiley & Sons，Inc.聚合物科学杂志B：聚合物物理，35：623-630，1997
Wide-angle x-ray diffraction (WAXD) of the ultra-high modulus and molecular weight polyethylene (UHMWPE) fibers at room temperature shows a predominantly orthorhombic structure with trace amount of nonorthorhombic crystals and very low amorphous contents. The calculated unit cell dimensions a and b of the orthorhombic crystals are 7.36 (±0.04) A, and 4.89 (±0.04) A, respectively. The apparent crystallite sizes perpendicular to the orthorhombic 110 and 200 reflection planes are 169.8 and 143.4 A, respectively. The crystallite size perpendicular to the nonorthorhombic 010 reflection is 149.4 A. The crystal density is calculated to be 1.02 g/cc. With increasing temperature, the thermal expansion coefficient in the a direction is much higher than that in the b direction which explains the structural transformation from the orthorhombic crystals to a pseudohexagonal form. Tension along the fiber axis while being heated during the high-temperature x-ray diffraction (HTWAXD) scanning has shown enhanced structural transformation from the orthorhombic form to the monoclinic form. Structural transformation from the orthorhombic form to the pseudohexagonal phase is not observed on the UHMWPE fibers under axial tension or annealing conditions in HTWAXD. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys, 35: 623–630, 1997