Characterization of celluloses by gel permeation chromatography

Gel permeation chromatography (GPC) applied to solutions of cellulose trinitrate in tetrahydrofuran (THF) has shown very promising results. Cellulose trinitrate was selected as the most suitable derivative for use in GPC because of several factors. The so‐called “solvent impurity” peak found in the chromatograms was shown to arise from dissolved air; the broadening of the peak observed with sample solutions was found to arise from other solvents and moisture. Indications are that THF does not rapidly degrade the dissolved trinitrate if the solution is stored with reasonable care. Nor did the dry trinitrate stored in a desiccator with exclusion of light degrade appreciably. Four cottons (one unpurified and three purified), two hardwood pulps, and two blends of hardwood and softwood were studied. Curves for the cottons indicated fairly broad, unimodal distributions. These were broadened considerably by acid hydrolysis. The degrees of polymerization (DP), although high, reflected the treatment applied. Wood pulps showed distributions broader than cotton, with much lower DP material, but also some material of even higher DP. A possible source of the latter is discussed. The distributions for the wood pulps were similar within the pairs but markedly different between the pairs. Some correlations were noted between GPC and pulp analytical data. Factors in the GPC technique itself, which may bear on the magnitude of the computed DP's, are pointed out and discussed.