Factors Affecting the Characteristics of CMC

The Temperature of the Etherification Process

The temperature of the etherification process plays an important role in the DS, degree of polymerization (DP), and other physicochemical properties such as viscosity, swelling behavior, thixotropy, etc., of the final product. The product’s best DS value is obtained only at a specific temperature. For instance, Pushpamalakar et al. (2006)obtained the highest DS of their products (0.821) at 45 °C reaction temperature. Above and below this temperature, the DS value decreased significantly. Golbaghi et al. (2017)obtained the best DS value of their sugarcane bagasse-derived CMC product at 57.85 °C after conducting dozens of reactions at different temperatures from 30 °C to 70 °C.

Similarly, Singh et al. (2012)reported the highest DS value of their corn cob-derived CMC products only at 60 °C temperature. Silva et al. (2004)investigated the effect of reaction temperature on the carboxymethylation of cashew tree gum-derived cellulose. DS value of their carboxymethylated product diminished considerably (i.e., from 0.75 to 0.16) as the reaction temperature was enhanced up to 70 °C from 30 °C. However, the reaction yield was increased (i.e., from 32% to 57%) at the same environmental conditions. Hence, the optimum temperature is not the same for every terrestrial or other cellulosic precursors. However, they introduced their reaction optimizing tendency within a specific range of temperatures. Outcomes of various studies revealed that most carboxymethylation reaction temperatures were optimized at 50 °C–60 °C for terrestrial precursors of cellulose . However, some exceptions have also been reported in other studies .

On the other hand, the optimum temperature crossed over 70 °C for the carboxymethylation while using various non-biological waste materials as a precursor of CMC . This phenomenon can be explained by facilitating the forward reaction kinetics of carboxymethylation as the temperature was raised to the optimizing point. Once the temperature is presented to an end, the posterior aggrandizement of the weather increases the reaction kinetics. Still, it induces the degradation of the cellulose structure in the presence of atmospheric oxygen, which diminishes the CMC production automatically. Therefore, the optimum temperature for carboxymethylation largely depends upon the precursor of cellulose to obtain the best production yield, and it is crucial to maintain the reaction temperature properly.