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Determination of Primary Amine Content in Bonding Agent Used in Composite Solid Propellants
Author(s) -
Oliveira José I. S.,
Pires Darci C.,
Diniz Milton F.,
Siqueira Jorge L.,
Mattos Elizabeth C.,
Rezende Luis C.,
Iha Koshun,
Dutra Rita C. L.
Publication year - 2014
Publication title -
propellants, explosives, pyrotechnics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.56
H-Index - 65
eISSN - 1521-4087
pISSN - 0721-3115
DOI - 10.1002/prep.201300147
Subject(s) - isopropylamine , amine gas treating , chemistry , hydrogen bond , primary (astronomy) , fourier transform infrared spectroscopy , organic chemistry , molecule , chemical engineering , physics , astronomy , engineering
The primary amine content in tetraethylenepentamine (TEPA) and TEPAN, a bonding agent used in composite solid propellants, was determined by near infrared (NIR) spectroscopy and the results were compared to those obtained by potentiometry. The band at 4930 cm −1 , which showed to be influenced only by primary amine groups, was chosen as the analytical band. The calibration curves based on isopropylamine (IPA) and isopropylamine/dibutylamine (IPA/DBA) mixtures proved to be suitable for determining the NH 2 content of TEPA or of samples containing mixtures of NH and NH 2 groups. It was found that TEPA contains 26.4 % of NH 2 and 25.7 % of NH, and that TEPAN contains 0.5 % of NH 2 , confirming the low content of primary amine of this bonding agent. The lowest amine equivalent of TEPA is 31.1±0.3 g/eq, as determined by potentiometry, was found because this technique measures the total hydrogen content, including primary and secondary amines. The literature value of 62.6 g/eq for TEPA ACROS obtained by potentiometry in a non aqueous medium and related to the first inflection of the primary amine, validates the value obtained by NIR in this work for a similar type of amine. The equivalent weight obtained by NIR spectroscopy (62.7 g/eq) allowed to calculate the molar mass of TEPA of 195.6 g mol −1 , which is close to the typical value of 200 g mol −1 .