Thermal decomposition of dialdehyde cellulose and its nitrogen-containing derivatives

A series of dialdehyde cellulose samples with varied aldehyde content were prepared, and they were further converted to nitrogen-containing derivatives by Schiff base reaction with hydroxylamine or hydrazine. Thermal decomposition of these compounds in nitrogen was studied by thermogravimetry/differential thermal analysis (TG/DTA). While the decomposition of unmodified cellulose in nitrogen started at about 280°C and rapid weight loss occurred at 300–340°C, the introduction of dialdehyde groups to cellulose resulted in significant shifts of decomposition to the lower temperature side. The samples of high degree of substitution showed two-step decomposition at around 220 and 280°C, indicating a basic change in the mode of decomposition. The nitrogen-containing derivatives showed changes in thermal decomposition similar to that of dialdehyde cellulose, but the samples with high degrees of substitution, above ∼70%, showed an explosive decomposition at 151–162°C. This anomalous phenomenon seems characteristic to the chemical structures involving CNN or CNO groups.