The analysis of rocket propellants by carbon-13 NMR

Abstract

Polybutadienes, polymerized via free radical mechanism to give an average molecular weight of 3000, were analyzed with carbon-13 NMR. The relative abundance of the three types of structural units (cis-1,4, trans-1,4, and vinylic-1,2 units) was quantitatively determined. The distribution of the three structural units was found to be completely random. Branching in the analyzed polymer was determined to be low (estimated to be less than 3 %). In hydroxyl-terminated-polybutadiene, two separate resonance signals from the hydroxyl-bearing end carbons were observed.

Six isomeric dinitrotoluenes and four isomeric trinitrotoluenes were characterized with carbon-13 chemical shifts, which can be used in the qualitative and quantitative analysis of mixtures of these compounds. Multiple linear regression analysis was performed on the chemical shifts to obtain parameters which are useful in estimating the chemical shifts of carbon-13 nuclei of methyl- and nitro- substituted benzenes.

Carbon-13 chemical shifts of other propellant ingredients (aliphatic nitrate esters, carboranes, plasticizers and stabilizers) are reported.