Preparation Of High-viscosity Carboxymethyl Cellulose(CMC) Derived From Bamboo Pulp And Its Reaction Mechanism

Bamboo(Neosinocalamus affinis) pulp was used as the raw material to prepare carboxymethyl cellulose(CMC) via solvent process. Different water content of isopropanol and ethanol were compared to select the best reaction medium. The result show that 90% ethanol was the best reaction medium. The influence of soaking time in ethanol, alkalization time, alkalization temperature, NaOH dosage, etherification time, ether ification temperature and etherif ication agent mass on carboxymethylatio was studied, and finally to explore the technological condition of preparing high viscosity CMC. And using the orthogonal test to validate their credibility. Conclusion follows:(1) It was found that the best reaction medium was 10 percent of water content of ethanol when alkaline condition:25℃, 1h, mass fraction of NaOH:30%, the ratio of NaOH dosage and raw material dosage was 1.4:1; etherification condition:60℃, 2h, the ratio of chloroacetic acid dosage and raw material dosage was 2.3:1, under which the viscosity of CMC was 1720mPa·s.(2) The optimized carboxymethylation condition using bamboo pulp as raw material was: as follows soaking time of ethanol:30min, alkalization time:60min, alkalization temperature:25℃, mass fraction of NaOH:35%, the ratio of NaOH dosage and raw material dosage was 1.2:1, etherification time:150min, etherif ication temperature:60 ℃, the ratio of chloroacetic acid dosage and raw material dosage was 2.3:1, it was found that the highest viscosity was 3050mPa·s. And it was demonstrated by that the optimized carboxymethylation condition was: as follows the water content of ethanol: 10%, soaking time of ethanol:30min, alkalization time:60min, etherification time:150min, under which the average viscosity was 3090mPa·s.(3) The influence of alkali adsorbing rate, swelling degree 、column size of bamboo pulp and the crystallinity of alkali cellulose which in different water content of reaction medium on carboxymethylation, and it reflects action mechanism of reaction medium and its water content on carboxymethylation. Meanwhile the viscosity of CMC and alkali adsorbing rate of bamboo pulp increased, the followed by the decrease with increase of water content of reaction medium. It explains that the higher of alkali adsorbing rate contribute to improving the viscosity of CMC within a certain range of sodium hydroxide concentration and dosage.