Hydrocelluloses with low degree of polymerisation from liquid ammonia treated cellulose

The heterogeneous hydrolytic degradation of cellulose after treatment with liquid ammonia has been studied. The level off degree of polymerisation (LODP) of liquid ammonia treated (LAT) linters is reached after 3 h when hydrolysed in hydrochloric acid (6.5 mol/l) at 60 °C. The hydrocelluloses were characterized as trimethylsilyl derivatives and as tricarbanilates. LODPs of non-activated celluloses were in the range from 55 to 77, while LAT celluloses had LODPs between 27 and 39. Trimethylsilyl derivatives and tricarbanilates gave almost identical elution curves in size exclusion chromatography indicating comparable hydrodynamic volumes. Glass transition temperatures of trimethylsilyl celluloses with DPs from 27 to 39 were found to be lower than those of the derivatives of the parent celluloses (Avicel, cotton linters) and showed a dependence on molar mass indicating that oligomeric celluloses are obtained by the method reported. Treatment of cellulose in aqueous ammonia was less efficient than liquid ammonia treatment.