Preparation of cellulose acetate membrane
Preparation of raw materials
To make cellulose acetate membrane, it is first necessary to prepare all kinds of raw materials. Cellulose acetate is the base material, and the one with good texture and high purity is selected to ensure the quality of the membrane. An appropriate amount of solvents is also required, such as acetone, dichloromethane, etc., which can dissolve cellulose acetate uniformly to form a suitable casting film solution. In addition, additives are also indispensable, such as plasticizers can improve the flexibility of the film, and porogens can regulate the pore size and porosity of the film.

The casting film solution is prepared
in a clean container, and the cellulose acetate is slowly added to the selected solvent according to the precise ratio. At the same time, an appropriate amount of additives are added. Turn on the stirring device and stir at a moderate speed to promote the full dissolution of cellulose acetate. During the stirring process, pay close attention to the temperature and time. If the temperature is too high, the solvent is volatile and may cause the degradation of cellulose acetate; if the time is too short, the dissolution or insufficient. Usually, maintain the temperature within a certain range and stir for several hours until the solution is uniform and transparent, without obvious particles and flocs, and the casting liquid is prepared.

Film making operation
Pour the prepared casting liquid on a clean, flat glass plate or other suitable support. With the help of a scraper or a film coating machine, apply the casting liquid evenly on the surface of the support at a constant speed and thickness. The coating process must be smooth to avoid bubbles and uneven thickness. Subsequently, the coated casting film solution is placed in a specific environment for gelation. Factors such as humidity, temperature and air circulation in this environment have a significant impact on the gelation process and the structure of the film. Generally speaking, in a constant humidity and temperature space, a few minutes to tens of minutes, the casting film liquid gradually gels to form a solid film.

Post-treatment step
The film formed by the gel still needs to be post-treated to improve its performance. First, the film is carefully peeled off from the support and soaked in deionized water. This step aims to wash away the remaining solvents and additives in the film and purify the structure of the film. After soaking for a certain period of time, change the water several times to ensure that it is cleaned. After that, the membrane can be dried. There are various drying methods, such as natural drying, oven drying or vacuum drying. However, the drying temperature and time need to be precisely controlled to prevent the membrane from shrinking, deforming or cracking. After proper drying, the cellulose acetate membrane is prepared, which can be used in subsequent fields such as filtration and separation.