Production & sales of microporous filtration membrane roll materials

Why does the microporous filter membrane roll deform and shrink greatly after cutting?

Issuing time:2023-11-08 14:59

Under normal storage conditions, it has not experienced the effects of high and low temperatures, but the filter membrane membrane deformed and shrunk seriously after being cut. What is the reason for this? Analyzing from the material itself, it is caused by the following reasons:

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1. The first point is that before cutting, the film roll depends on the type of material used. For example, the polymer itself has a thermal expansion coefficient and will expand or contract with changes in temperature, because some processes will It undergoes a cooling process, which generates internal stress or tension within the material. Over time, the internal stress or tension within the polymer chain will reach an equilibrium state. This stress relaxation process involves the internal stress within the polymer structure. Therefore, even if most membrane materials are not cut, they will shrink in different procedures. After cutting, this situation will be even worse. Cutting releases the internal stress of the membrane. One of the most prominent manifestations is shrink.

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2. Relaxation of oriented polymer chains. In some cases, microfiltration membranes are produced using a process that arranges the polymer chains in a specific direction. This orientation can be achieved by stretching or other mechanical techniques. When the membrane is When cutting, the oriented polymer chains are released from the applied tension, causing relaxation and contraction, thereby shrinking the overall dimensions of the membrane.

3. Remove external supports. During the production process, microfiltration membranes are usually supported by frames, brackets or substrates. The main function is to maintain the shape and stability of the membrane. When the membrane is removed from these external supports, the structure of the membrane itself The frame carries some of the support, but when cut, it loses this structural support that helps maintain its size. The end result is that the membrane may shrink due to the release of internal stresses.

4. The influence of temperature, here we mainly talk about the thermal cutting process, which will also cause the film to shrink, because the heat applied during the cutting process will cause local heating and thermal expansion of the film material, and once the heat is removed subsequently, the material will shrink due to cooling and shrink.

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One thing we need to understand is that the degree of shrinkage of the film after cutting will vary depending on the specific film material and manufacturing process. One film will have relatively small or no shrinkage after cutting, while other films may show more shrinkage. Significant shrinkage, at the same time, the shrinkage rate of the membrane also depends on the cutting technology used, such as mechanical cutting, laser cutting or other methods, etc. Therefore, in order to minimize the shrinkage of the microfiltration membrane after cutting, it is recommended to work with the membrane manufacturer Shrinkage conditions, control the cutting process, including temperature, speed and cutting method used. After cutting, ensure that the film is left to rest and balance in a stable environment. This will also help relieve some internal stress and reduce shrinkage.

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