Distribution of molar mass and branching index of natural rubber from hevea brasiliensis trees of different age by size exclusion chromatography coupled with online viscometry
| Autor: | Nicolai Aust, Michael Parth, Klaus Lederer |
|---|---|
| Rok vydání: | 2002 |
| Předmět: |
Chromatography
Molar mass Polymers and Plastics biology Chemistry Organic Chemistry Size-exclusion chromatography Condensed Matter Physics Branching (polymer chemistry) biology.organism_classification Gel permeation chromatography Natural rubber visual_art Mole Materials Chemistry visual_art.visual_art_medium Molar mass distribution Hevea brasiliensis |
| Zdroj: | Macromolecular Symposia. 181:447-456 |
| ISSN: | 1521-3900 1022-1360 |
| DOI: | 10.1002/1521-3900(200205)181:1<447::aid-masy447>3.0.co;2-b |
| Popis: | Natural rubber from hevea brasiliensis trees (Thailand, RRIM 600 clone) of different age (8, 20, and 35 years) were characterized by size exclusion chromatography (SEC) coupled with online viscometry with respect to their distribution of molar mass and branching index at a temperature of 70 °C using cyclohexane as solvent. The natural rubber samples were purified by washing with an aqueous solution of sodium dodecylsulfate and subsequent saponification. With this procedure physical branching points caused by phospholipids, proteins and hydrophobic terminal units, mainly fatty acids, of the natural rubber (cis-1,4-polyisoprene) molecule, could be removed leading to completely soluble polymer samples. All samples investigated possess a very broad (10 to 50,000 kg/mol) and distinct bimodal molar mass distribution. With increasing age of the trees the peak area in the low molar mass region decreases favoring the peak area in the high molar mass region. By plotting the branching index as a function of the molar mass it could be shown that branching of the natural rubber increases with both, the molar mass and the age of the trees. |
| Databáze: | OpenAIRE |
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