Molecular structure of polyacrylonitrile

Polyacrylonitrile (PAN) is a type of polymer that is made from the monomer acrylonitrile. PAN has a linear structure and the repeating unit is -CH2-CH(CN)-. Since the carbon-carbon bond on the polymer main chain is a single bond, the chain is flexible and can move to a certain extent, which helps the material to be processed into Fiber or membrane capacity. Also important is the presence of the nitrile (-CN) group, which is polar, meaning it attracts water molecules, making PAN somewhat hydrophilic or water-absorbent. In addition, the nitrile groups can participate in hydrogen bonding, which endows the material with additional properties.

What are the characteristics of polyacrylonitrile filter membrane?

1. Chemical resistance, PAN is resistant to most inorganic chemicals. This makes PAN films useful in environments where exposure to such chemicals may occur. Polyacrylonitrile is a polymer composed of repeating units of acrylonitrile monomers. Since acrylonitrile contains cyano groups (C=N), it forms strong covalent bonds within the polymer chain and is resistant to various inorganic chemicals. Inorganic chemicals usually contain polar functional groups or ions that interact with polar materials, while the non-polar nature of PAN film, it has minimal interaction with polar inorganic chemicals, resulting in increased resistance. In addition, PAN membranes can be crosslinked, which involves chemically linking adjacent polymer chains, and crosslinking enhances membrane stability and resistance to chemical attack. It reduces the fluidity of the polymer chains, making the membrane less prone to swelling or dissolution by inorganic chemicals. Polyacrylonitrile films themselves are usually high molecular weight materials with stronger intermolecular forces and higher stability, making them more resistant to chemical degradation.

2. Thermal stability, PAN has good thermal stability, which makes it suitable for applications that may be exposed to high temperatures. Withstands a wide temperature range, typically operating effectively from approximately -20°C to 80°C, maintaining its structural integrity and filtration performance without significant degradation. In practical applications, it is worth noting that extreme temperatures at the upper or lower end of this range may affect membrane properties and performance. Therefore, in the selection process, the specific application requirements and critical conditions for temperature limitations should be considered.

3. Hydrophilicity and mechanical strength. It can be seen from its structure that the nitrile group makes the PAN membrane hydrophilic. This means that PAN membrane has good water absorption and can be used in filtration applications; likewise, it also has good mechanical strength, durability of the membrane and ability to resist strong physical stress.

Which industries are polyacrylonitrile membranes used in?

1. In the water treatment industry, PAN membranes are commonly used in microfiltration and ultrafiltration processes for water and wastewater treatment due to their hydrophilicity and chemical resistance. They can effectively remove suspended solids, particulate matter, bacteria, viruses and other pollution in water sources things.

2. Pharmaceutical and biotechnology, in these industries, PAN membranes can be used for the filtration of solutions, because they can resist a wide range of pH values and have good thermal stability, complete tasks such as sterilization, clarification and separation processes, and can Filtration of microorganisms, particles and impurities in liquids, gases and pharmaceutical formulations.

3. In the food and beverage industry, PAN membranes are used for the filtration of beverages and other foods due to their chemical and thermal stability, including clarification, sterilization, and removal of particles and microorganisms in liquids, helping to ensure product quality and safety.

4. In the chemical industry, due to its chemical resistance, PAN membranes are used in various chemical separation processes, catalyst recovery and impurity removal, as well as the filtration of solid particles, scale and other pollutants in the production process stream, etc.

5. Textile industry, PAN is used to make textile fibers because of its high mechanical strength and flexibility. Although this is not a filtering application, it is worth mentioning given the widespread use of PAN in the industry.