PRECISE EQUIVALENT WEIGHT DETERMINATION OF BRANCHED GLYCIDYL AZIDE POLYMERS BY NMR SPECTROSCOPY

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Authors
  1. Desilets, S.
Corporate Authors
Defence Research Establishment Valcartier, Valcartier QUE (CAN)
Abstract
In order to develop an exact equivalent weight method for branched glycidyl azide polymer (GAP), an acetylation study of linear polyepichlorohydrin (PECH), linear and branched GAPs was made by using different alcohol substituents such as TFA or HFA. It was found by IR spectroscopy of the derivatives that TFA and HFA were not strong enough for a complete reaction on branched GAPS. This incomplete reaction was responsible for the unsuccessful equivalent weight determination of those derivatives. A better reaction condition was obtained with acetic anhydride/pyridine heated overnight at 95C, followed by coevaporations with toluene. Acetylation was complete for PECH while for GAPs it seems, by the IR band at 3360 cm 1(-), that it was not even with this strong acetylation. Deuterium exchange expeirments with D3O proved that this IR absorption was an overtone or a combination band and that acetylation was in fact completed. Complete acetylation reactions were tried on fourteen prepolymers with different structures including the branched GAPs. The OH equivalent weights of these prepolymers were then determined by 1H NMR spectroscopy of the acetyl derivaties. The precision of the method was between 5-10% and the sensitivity limited a precise determination to equivalent weight below 5000. The values determined and this method are now currently used for propergol and explosive formulations by chemists and engineers at DREV.
Report Number
DREV-4740/94 —
Date of publication
01 Mar 1994
Number of Pages
47
DSTKIM No
94-03027
CANDIS No
139840
Format(s):
Hardcopy;Document Image stored on Optical Disk

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