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United States Department of Agriculture

Agricultural Research Service

Title: A Convenient Low-Resolution NMR Method for the Determination of the Molecular Weight of Soybean Oil-Based Polymers

Author
item Doll, Kenneth

Submitted to: Journal of the Association for Laboratory Automation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 3, 2009
Publication Date: August 1, 2009
Citation: Doll, K.M. 2009. A Convenient Low-Resolution NMR Method for the Determination of the Molecular Weight of Soybean Oil-Based Polymers. Journal of the Association for Laboratory Automation. 14(4):185-189.

Interpretive Summary: We have developed a method using a low resolution instrument to gain information that was previously only available using significantly more expensive technology. Due to its chemical structure, soybean oil undergoes chemical changes when it is heated in the absence of oxygen, or with various chemical catalysts. One thing that changes significantly is the size of the molecules. We developed a method to study these changes using a low resolution nuclear magnetic resonance spectrometer, commonly available in many laboratories. This work is a benefit to many laboratories which may have the low resolution instrument, but do not have access to the higher technology.

Technical Abstract: By studying a series of soybean oil based polymers, using low resolution nuclear magnetic resonance (NMR) spectroscopy, an easy method to study molecular weight was developed. The relationship between a polymer’s molecular weight and the instrument’s response can be correlated in a linear relationship. Correlation constants (r2) of 0.988, when data was taken at -10ºC, and 0.999, when the study was done at 0ºC, were observed. Overall, this method is simple and with instrument modification, could be applied to other types of polymers as well.

Last Modified: 11/22/2014
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