Pay Attention To These Matters When Using Nylon Microporous Membranes

Two categories of nylon filter membranes

HAWACH has summarized 7 points to be noticed when using Nylon microporous membranes. But, before we understand the use notes of nylon (Nylon) microporous filter membrane, we should first understand the molecular structure of the important component “nylon” in the filter membrane. Commonly used nylon can be divided into two categories.

1. Polyhexamethylene adipate
Different nylon products can be obtained based on the number of carbon atoms number of the diamine and dibasic acid used.

2. Obtained by polycondensation or ring-opening polymerization of caprolactam
The chemical structure of its long-chain molecule is H-[NH(CH2)XCO]-OH
They are named based on the carbon atoms’ numbers contained in their unit structure. For example, nylon 6 shows that it is obtained by ring-opening polymerization of caprolactam containing 6 carbon atoms.

Since the -CH2- (methylene) in the nylon molecule can only generate weak van der Waals force, the molecular chain of the -CH2- segment part has a higher degree of curling. The intermolecular hydrogen bonding forms are not completely the same, and the molecular curling probability is also different, due to the different number of -CH2- in various nylons. What’s more, directionality exists in some nylon molecules.

0.22 Cellulose Acetate Membrane Filters 0.45 Cellulose Acetate Membrane Filters Disc

Use notes of Nylon microporous membranes

We should pay attention to these matters when using nylon (Nylon) microporous membrane.

① Used for bubble point determination: the bubble point pressure can reflect the pore size of the microporous membrane, which is closely related to the quality of the filtered liquid. At about 70℃ for 1 h, soke the microporous membrane in water for injection in advance. Pour out the water and soak it in warm water for injection overnight for later use. Take it out just before use, rinse it with water for injection, then put it into the filter for use and installation. When preventing the filter membrane from crooked and leaking.

② In order to protect and extend the service life of the filter membrane, filter paper or silk cloth of the same size, can be used.

③ The pore size of the microporous filter membrane is cone-shaped. The smooth side has a small pore size as the front side; the rough side has a large pore size as the opposite side. When installing, the front side (smooth side) should face up, and the reverse side (dark side) should face down, otherwise, The pore size is easily blocked by impurities and affects the filtration rate. When the temperature is low, the treated filter membrane should be soaked in water for injection at the same temperature as the chemical solution for 5 to 10 minutes to avoid rupture caused by the drop in tensile strength of the filter membrane due to the temperature difference.

④ On the skin tube head of the exhaust pipe of the filter holder, fix a 16-gauge infusion needle, which is controlled by a water stop clip, which can prevent the filter membrane from rupturing due to excessive exhaust pressure and speed.

⑤ According to the concentration and viscosity of the liquid medicine, microporous membranes with different pore diameters should be selected.

⑥ If there are small holes or cracks in the microporous filter membrane, you can rinse it with the unused broken filter membrane and dry it, then shred it and place it in a small cup of acetone. Stir it into a paste-like mucus. The mucus should be covered with a little larger.

⑦ When a multi-stage filtration device with coarse filtration followed by fine filtration is used for infusion filtration, microporous membranes can be used for fine filtration afterward, and pressure, decompression, and azimuthal static pressure filtration methods should be adopted.