کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5420952 | 1395485 | 2006 | 9 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Molecular dynamics of poly(l-lactide) biopolymer studied by wide-line solid-state 1H and 2H NMR spectroscopy
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی تئوریک و عملی
پیش نمایش صفحه اول مقاله
![عکس صفحه اول مقاله: Molecular dynamics of poly(l-lactide) biopolymer studied by wide-line solid-state 1H and 2H NMR spectroscopy Molecular dynamics of poly(l-lactide) biopolymer studied by wide-line solid-state 1H and 2H NMR spectroscopy](/preview/png/5420952.png)
چکیده انگلیسی
The molecular dynamics of poly(l-lactide) (PLLA) biopolymer was characterized through analyses of 1H and 2H NMR line-shapes and spin-lattice relaxation times at different temperatures. At low temperatures (e.g. 90 K), the methyl group rotation is dominant leading to a significant reduction in the proton second moment. Fast methyl group reorientation occurs at ca. 130 K. In additional to the fast methyl group rotation, hydroxyl groups start to reorient as the temperature increases further, eventually leading to the breakdown of the segments of the biopolymer chains above its glass transition temperature Tg of 323 K. The analyses of the 2H NMR line-shapes indicate that both the methyl and hydroxyl reorientations can be described by the so-called cone model, in which the former has three equilibrium positions with θC-D=70.5â and Ï=120° while the latter one exhibits two equilibrium positions with θO-D=78â and Ï=180°.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Solid State Nuclear Magnetic Resonance - Volume 29, Issue 4, June 2006, Pages 258-266
Journal: Solid State Nuclear Magnetic Resonance - Volume 29, Issue 4, June 2006, Pages 258-266
نویسندگان
Farhod Nozirov, Alovidin Nazirov, Stefan Jurga, Riqiang Fu,