Free-volume and crystallinity ion low molecular weight poly(ethylene oxide)
Free-volume and crystallinity ion low molecular weight poly(ethylene oxide)
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DOI：
10.1002/polb.21242
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发表时间：
2007-09-01
影响因子：
--
通讯作者：
Windmoller, Dario
中科院分区：
文献类型：
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作者：
Machado, Jose C.;Silva, Glaura G.;Windmoller, Dario
用正电子湮没寿命谱（帕尔斯）、差示扫描量热法、X射线衍射和偏光显微镜研究了平均摩尔质量为1 × 10（3）~ 10 × 10（3）g mol（-1）的六种低摩尔质量聚环氧乙烷样品。动态光散射用于严格测定摩尔质量和多分散性。聚合物样品的结晶度为70-95%，这是一个不寻常的范围，在帕尔斯的研究，制备熔融材料淬火。由自由体积模型确定的正电子素拾取寿命（τ（3））和相对自由体积分数（f（v））与聚合物的平均摩尔质量和结晶度良好相关。X射线衍射和偏振光光学数据支持正电子湮没结果的解释。与高空穴含量相关的帕尔斯参数13对于所有样品保持大致恒定在20-22%。对于低结晶度样品（例如，对于M-w = 1390）和在界面处和在更结晶的材料的层间球晶区域中。(c)2007 Wiley Periodicals，Inc.
Positron annihilation lifetime spectroscopy (PALS), differential scanning calorimetry, X-ray diffraction, and polarized light optical microscopy were used to study six low molar mass poly(ethylene oxide) samples with average molar masses ranging from 1 X 10(3) to 10 X 10(3) g mol(-1). Dynamic light scattering was used to determine molar mass and polydispersity rigorously. Polymer samples with 70-95% crystallinity, which is an unusual range in PALS studies, were prepared by molten material quenching. The ortho-positronium pick-off lifetime (tau(3)) and relative fractional free volume (f(v)), determined by the free volume model, correlated well with the average molar mass and crystallinity of the polymers. X-ray diffraction and polarized light optical data support the interpretation of positron annihilation results. PALS parameter, 13, which is associated with high cavity content, remained approximately constant at 20-22% for all samples. The cavities are present as crystallite defects in the spherulitic open texture and the amorphous phase for the low crystallinity sample (e.g., for M-w = 1390) and at the interfaces and in interlamellar spherulite regions of the more crystalline materials. (c) 2007 Wiley Periodicals, Inc.