Star-like macromers from lignin
Star-like macromers were prepared from hydroxypropyl lignin by reaction with propylene oxide. The average number of arms per macromer was controlled by partial capping with diethylsulfate, and the average arm length by the degree of chain extension with propylene oxide. Six methods of analysis wer...
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ndltd-VTETD-oai-vtechworks.lib.vt.edu-10919-432552021-05-05T05:40:39Z Star-like macromers from lignin Oliveira, Willer de Forest Products LD5655.V855 1987.O448 Lignin Wood -- Chemistry Star-like macromers were prepared from hydroxypropyl lignin by reaction with propylene oxide. The average number of arms per macromer was controlled by partial capping with diethylsulfate, and the average arm length by the degree of chain extension with propylene oxide. Six methods of analysis were applied for characterizing of the star-like macromers: total hydroxyl (by titration), vapor pressure osmometry, hydriotic acid/gas chromatography, ultraviolet spectroscopy, proton-nuclear magnetic resonance spectroscopy and thermal analysis. Number average molecular weights were measured by vapor pressure osmometry. Total hydroxyl content was determined after acetylation by potentiometric titration. Based on HPL molecular weight and hydroxyl content it was estimated that the average HPL molecule generates a star-like structure ("macromer”) with an average of 6 arms. Hydriodic acid/gas chromatography proved to be the most appropriate method for the quantitative determination of the degree of capping. Based on this technique it was possible to classify star-like macromers with between two and six radiating arms per average molecule. The same method could also be applied for the determination of arm length. Two different propoxylation reaction conditions produced macromers with an average of 2.5 and 3.5 propylene oxide units per arm. Ultraviolet spectroscopy was the simplest and most rapid method of analysis investigated. The decrease in copolymer absorptivity coefficient was found to be related to an increase in non-UV absorbing mass after capping and/or chain extension. Results indicated that H-NMR spectroscopy is an adequate method of analysis for star-like macromers. Macromer arm length was calculated from the ratio of signals representing the methyl group of acetyl (i.e. hydroxyl) and propoxyl functionality. Two levels of propoxylation produced star-like macromers with 2.2 - 2.5 and 3.9 - 4.0 propylene oxide units per arm. Thermal analysis by DMTA of lignin derivative-containing blends with ethylene-vinyl acetate copolymer indicated that the glass transition behavior of the star-like macromers follows the Gordon-Taylor relationship for copolymers. Although variable, the results revealed a consistent decrease in T<sub>g</sub> as a consequence of an increase of propylene oxide chain length. Master of Science 2014-03-14T21:38:22Z 2014-03-14T21:38:22Z 1987 2010-06-12 2010-06-12 2010-06-12 Thesis Text etd-06122010-020340 http://hdl.handle.net/10919/43255 http://scholar.lib.vt.edu/theses/available/etd-06122010-020340/ OCLC# 17559208 LD5655.V855_1987.O448.pdf In Copyright http://rightsstatements.org/vocab/InC/1.0/ xii, 99 leaves BTD application/pdf application/pdf Virginia Tech |
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LD5655.V855 1987.O448 Lignin Wood -- Chemistry |
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LD5655.V855 1987.O448 Lignin Wood -- Chemistry Oliveira, Willer de Star-like macromers from lignin |
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Star-like macromers were prepared from hydroxypropyl lignin by reaction with propylene oxide. The average number of arms per macromer was controlled by partial capping with diethylsulfate, and the average arm length by the degree of chain extension with propylene oxide.
Six methods of analysis were applied for characterizing of the star-like macromers: total hydroxyl (by titration), vapor pressure osmometry, hydriotic acid/gas chromatography, ultraviolet spectroscopy, proton-nuclear magnetic resonance spectroscopy and thermal analysis.
Number average molecular weights were measured by vapor pressure osmometry. Total hydroxyl content was determined after acetylation by potentiometric titration. Based on HPL molecular weight and hydroxyl content it was estimated that the average HPL molecule generates a star-like structure ("macromer”) with an average of 6 arms.
Hydriodic acid/gas chromatography proved to be the most appropriate method for the quantitative determination of the degree of capping. Based on this technique it was possible to classify star-like macromers with between two and six radiating arms per average molecule. The same method could also be applied for the determination of arm length. Two different propoxylation reaction conditions produced macromers with an average of 2.5 and 3.5 propylene oxide units per arm.
Ultraviolet spectroscopy was the simplest and most rapid method of analysis investigated. The decrease in copolymer absorptivity coefficient was found to be related to an increase in non-UV absorbing mass after capping and/or chain extension.
Results indicated that H-NMR spectroscopy is an adequate method of analysis for star-like macromers. Macromer arm length was calculated from the ratio of signals representing the methyl group of acetyl (i.e. hydroxyl) and propoxyl functionality. Two levels of propoxylation produced star-like macromers with 2.2 - 2.5 and 3.9 - 4.0 propylene oxide units per arm.
Thermal analysis by DMTA of lignin derivative-containing blends with ethylene-vinyl acetate copolymer indicated that the glass transition behavior of the star-like macromers follows the Gordon-Taylor relationship for copolymers. Although variable, the results revealed a consistent decrease in T<sub>g</sub> as a consequence of an increase of propylene oxide chain length. === Master of Science |
author2 |
Forest Products |
author_facet |
Forest Products Oliveira, Willer de |
author |
Oliveira, Willer de |
author_sort |
Oliveira, Willer de |
title |
Star-like macromers from lignin |
title_short |
Star-like macromers from lignin |
title_full |
Star-like macromers from lignin |
title_fullStr |
Star-like macromers from lignin |
title_full_unstemmed |
Star-like macromers from lignin |
title_sort |
star-like macromers from lignin |
publisher |
Virginia Tech |
publishDate |
2014 |
url |
http://hdl.handle.net/10919/43255 http://scholar.lib.vt.edu/theses/available/etd-06122010-020340/ |
work_keys_str_mv |
AT oliveirawillerde starlikemacromersfromlignin |
_version_ |
1719402598675513344 |