Carboxymethylcellulose characters of CMC. The precise control of

Carboxymethylcellulose (CMC), natural polyelectrolytes derived from cellulose
by introducing carboxyl methyl group (–CH2COOH), have attracted
considerable interests in a wide range of biomedical applications 1.

The molecular weight of
the polymer, average number of carboxyl content per anhydroglucose unit, and the distribution of carboxyl substituents
along the polymer chains are the main factor governing
the characters of CMC. The precise control of the structure and the
determination of substituent distribution of CMC are of primary importance for
the elucidation of structure-property relationships (necessary to optimize the
performance of the final product) and for the product quality control 2.

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Various
industrial gums (like gum arabic, gum tragacanth, gum xanthan, sodium alginate,
chitosan, carboxymethylcellulose, hydroxyethylcellulose, and methylcellulose)
were characterized thermally using DSC and TGA under a nitrogen atmosphere, thermal transitions,
as well as activation energies of the major decomposition stages 3-6.

The polymers vary extensively in their
ability to withstand deterioration when exposed to the same environment. These
differences instabilities are due mainly
to chemical structure, but also may be caused by impurities which are frequently
present in the polymer at trace levels. In a distinctive exposure to the environment, polymeric degradation can be
caused by both reactive chemicals like oxygen or water, and by various sources
of energy such as heat, UV radiation or mechanical stress. It is well known
that heat accelerates polymeric degradation in the presence and absence of
chemical reactants. In fact, most thermal analysis methods used to study
polymer stability receive the advantage
of this general occurrence to acquire a lot of experimental data in a short
time 7.

Thermal analysis is one of the
mainstay families of techniques for the physical and on occasion’s chemical
characterization of pharmaceutical materials. Thermal analysis is useful not
only to help the researcher and manufacturer in increasing effective additive
systems for polymers but also to aid the user in evaluating whether a polymeric
material has the anticipated processing properties and routine characteristics
7. The
long history of using thermal methods within the vicinity and the important diversity
of applications to which these methods placed,
reflect the prerequisite of developing consistent and adaptable characterization
technique for the successful development of pharmaceutical products. In reality,
it is attractive to reflect that one of the input focus areas of the industry, next to drug discovery, is
analytical development, an area even more significant by the recent Process
Analytical Technologies initiative launched by the United States Food and Drug
Administration (FDA) whereby the product-to-market process may be accelerated
if proper validation of each stage of manufacture is provided 8.