Premium
Determination of degree of nitration of nitrocellulose by refractometry
Author(s) -
Kohlbeck J. A.,
Bolleter W. T.
Publication year - 1968
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1968.070120808
Subject(s) - refractometer , nitrocellulose , refractometry , refractive index , nitration , degree (music) , spectrum analyzer , optics , materials science , analytical chemistry (journal) , molar absorptivity , substrate (aquarium) , chemistry , chromatography , physics , organic chemistry , acoustics , biochemistry , oceanography , membrane , geology
Nitrocellulose (NC) films, when dried on a rigid substrate, tend to be biaxial and thus exhibit two refractive indices. The absolute difference between these indices has been found to provide an accurate measure of the degree of nitration of NC. A film of NC is cast from a 1% solution in butyl acetate to provide a film about 0.5 mil thick. The dry film, when placed in an Abbé‐3L refractometer, gives two white lines which go to extinction alternately upon rotation of a cap analyzer through the east–west (EW) and north–south (NS) directions. Refractive index measurements are made using the line visible in each direction of the analyzer. The absolute difference between the two indices is related to the degree of nitration through standard curves for various grades of NC. The standard deviation for the proposed method was found to be ±0.01% N.