The performance of hollow fiber ultrafiltration membranes relies on scientific composition methods and precise process control. The essence of its preparation process is to transform polymeric raw materials into hollow fiber morphology with specific pore size distribution and separation characteristics, and to ensure structural stability and functional reliability through multi-step control.
Preparation is typically based on polymer solutions, using phase inversion as the core process. First, the selected polymer is dissolved in a suitable solvent to form a homogeneous casting solution, and appropriate additives are added to adjust viscosity and porosity. Then, the hollow fiber prototype is formed by extrusion through a spinneret, and phase separation occurs in a specific gel bath, allowing solvent and non-solvent exchange, promoting polymer solidification and the formation of a microporous structure. The temperature, concentration, flow rate, and gelation conditions at this stage directly affect the fiber inner diameter, wall thickness, and pore size uniformity, which are crucial in determining separation accuracy and flux.
To optimize performance, modification treatment is often performed after membrane formation. Surface hydrophilic modification is a common method, achieved through plasma treatment, UV grafting, or coating with hydrophilic coatings, to reduce contaminant adhesion and improve antifouling capabilities. For applications requiring special chemical or temperature resistance, nanoparticles or weather-resistant resin blends can be introduced into the spinning solution to form a composite structure and enhance overall durability.
Component assembly is also a crucial part of the process. A large number of single hollow fibers are encapsulated in a shell at a specific density and arrangement, with both ends sealed with resin and inlet ports provided, forming a modular unit. A reasonable packing density and flow channel design can balance hydraulic distribution, reduce concentration polarization, and thus maintain long-term high-flux operation.
Overall, the composition method of hollow fiber ultrafiltration membranes integrates materials science, spinning engineering, and interface control. By precisely controlling the parameters of each step, synergistic optimization of structure and performance is achieved, laying a solid foundation for their stable and efficient application in water treatment, food, and pharmaceutical fields.
