Synthesis And Characterization Of Cotton Stalk Cellulose Carbamate In Ionic Liquid

Synthesis technology of cellulose carbamate in two ionic solutions such as l-ethyl-3-methylimidazole bromide and l-butyl-3-methylimidazole chloride was studied in this paper, and then cellulose carbamate was synthesized successfully. The effect of factors on the nitrogen content of the products was investigated. The optimal synthesis condition and effect degree were obtained through orthogonal experiments. The structure of modified cellulose was characterized by Fourier transform infrared spectroscopy. The nitrogen content of modified cellulose synthesized in different reaction condition was mensurated by Micro-Kjeldahl method. The conclusion as follows:1. Synthetic method of l-ethyl-3-methylimidazole bromide were confirmed, and synthetic method of cellulose carbamate in l-ethyl-3-methylimidazole bromide were confirmed. In accordance with the results of single fator experiment, and the results show that the nitrogen content of the cellulose carbamate evidently increases with the protracting of the activation time and esterification time and the increasing of the esterification temperature. The optimal synthesis condition is that activation time is5h, esterification time4h, and the esterification temperature is145℃according to orthogonal experiments. The effect degree:activation time>esterification time>esterification temperature.2. Synthetic method of l-butyl-3-methylimidazole chloride were confirmed, and synthetic method of cellulose carbamate in l-butyl-3-methylimidazole chloride were confirmed. In accordance with the results of single fator experiment, and the results show that the nitrogen content of the cellulose carbamate evidently increases with the protracting of the activation time and marination time of urea solution and the increasing of the esterification temperature. The optimal synthesis condition is that activation time is6h, marination time of urea solution is16h, and the temperature of esterification is150℃according to orthogonal experiments. The effect degree:activation time>esterification temperature> marination time of urea solution.3. The structure of cellulose carbamate was characterized by Fourier transform infrared spectroscopy. IR spectra of cotton stalk cellulose and cellulose carbamate are shown in figure. Comparing pristine cellulose, we can see that the cellulose carbamate has an obvious new absorption peak at1710cm-1, which was assigned to the stretching vibration of the carbonyl(C=O) in the base of urethane. The absorption peaks of the amidocyanogen (N-H) an hydroxyl (O-H) overlap and broaden at3700-30O0cm-1. These indicated that urea had reacted with cotton cellulose to form cellulose carbamate. The absorption band at1710cm-1gradually increased with increasing the nitrogen content of the cellulose carbamate on the basis of Micro-Kjeldahl results. 4. Polymerization degree of cotton stalk cellulose was determined by viscosimetry. The results indicated that the polymerization degree of cotton stalk cellulose inclined to decrease along with activation time.