1. Select the No. 3 rotor and a 200ml beaker, and prepare the sodium carboxymethylcellulose CMC with deionized water at about 60°C to prepare an aqueous solution with a mass fraction of 1%;
2. After stirring and dissolving, seal it and place it in a constant temperature and humidity box at 25°C for 18h;
3. Take out to make up the amount of evaporated water, and stir well until there is no floc;
4. Then, after standing for a period of time in a constant temperature and humidity box at 25 °C, the measurement was carried out at 25 ± 0.5 °C.