Isothermal Thickening and Thinning Processes in Low Molecular Weight Poly(ethylene oxide) Fractions Crystallized from the Melt. 5. Effect of Chain Defects
Isothermal Thickening and Thinning Processes in Low Molecular Weight Poly(ethylene oxide) Fractions Crystallized from the Melt. 5. Effect of Chain Defects
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DOI：
10.1021/ma960048q
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发表时间：
1996-12
期刊：
影响因子：
5.5
通讯作者：
Seung-Wook Lee;E. Chen;A. Zhang;Y. Yoon;B. Moon;Sangkug Lee;and Frank W. Harris;Stephen Z. D. Cheng;E. V. Meerwall;Benjamin S. Hsiao and;R. Verma;J. Lando
中科院分区：
文献类型：
--
作者：
Seung-Wook Lee;E. Chen;A. Zhang;Y. Yoon;B. Moon;Sangkug Lee;and Frank W. Harris;Stephen Z. D. Cheng;E. V. Meerwall;Benjamin S. Hsiao and;R. Verma;J. Lando
Two-arm poly(ethylene oxide) (PEO) fractions with different molecular weights (MWs) have been prepared. For each fraction, both arms have equal lengths of MW = 2300 or 5500. The MWs and molecular weight distributions of two-arm PEOs after fractionation are determined from vapor pressure osmometry, gel permeation chromatography, and light scattering. Compared to linear PEO fractions with similar molecular lengths, the two-arm PEOs can be viewed as linear chains with a well-defined defect at the center of the molecule. Self-diffusion coefficients of the two-arm PEOs are measured and compared with linear PEOs having molecular lengths equivalent to both a single arm and a whole molecule. The crystallization behavior of the PEOs is monitored via wide angle X-ray diffraction, small angle X-ray scattering, and differential scanning calorimetry. Over a wide undercooling range, the two-arm PEO molecules do not appear to recognize the defects at the center of the chains during the initial stage of crystallization. ...
