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Electrospinning is affected by many factors. Sometimes even if the spinning is carried out according to the instructions, the experiment will fail. Here are some common problems in the experiment for readers' consideration.
(1) What is the reason for the occurrence of gel during the preservation of spinning solution?
Answer: because some solutions have certain requirements for storage temperature, when the spinning solution is lower than a certain temperature, the viscosity will gradually increase, and the needle tip is prone to gel strips, which will grow and lengthen until they fall off. At the same time, the humidity of the air source should not be too high to avoid the problem that the solution viscosity changes or the wet gas contacts the needle tip, resulting in the failure of normal continuous spinning. It is recommended to prepare and use it now or keep it sealed for 2 days.
(2) What is the reason why the fiber diameter distribution is large and the fiber diameter is thick?
Answer: generally, the concentration of spinning solution is too high. It is recommended to continue to reduce the concentration of the solution. In addition, some solutions with too high molecular weight, too high molecular entanglement in the solution, increased viscosity and insufficient stretching force will also lead to coarsening of fiber diameter.
(3) Why does the solution have a lot of lumps?
Answer: it is generally caused by the failure of the agitator or or magnetic stirrer to disperse the agglomerated powder in time during the preparation process. Therefore, when adding the material powder, gradually add the material powder while stirring the solvent, so as to avoid the agglomeration of the material powder.
(4) Why is there a layer of water on the surface of spinning solution?
Answer: generally, after the solution is standing for a long time, water is easy to separate out from the mixed system. Therefore, the solution should not be left standing for a long time and should be stirred again before use.
(5) Why are there obvious liquid spots or marks on the film surface?
Answer: the cause of liquid point is generally that the spinning solution concentration is too low, resulting in the jet in the form of spray. Generally, the cause of liquid mark is that the solution concentration in the spinning solution is too high, resulting in the increase of solution viscosity. Under the current volatile environment and stretching force, the jet cannot complete the splitting and completely solidify into fibers.
(6) Under the scanning electron microscope, what is the reason for more beads on the fiber?
Answer: generally, the concentration of the spinning solution is too low, resulting in insufficient viscosity of the spinning solution. It is recommended to continue to increase the concentration of the solution. Generally, with the increase of the concentration of spinning solution, the products will change from micro nano particles, beaded fibers, uniform fibers to coarse fibers; In addition, the molecular weight of some solutions is too small, and the molecular entanglement in some solutions is insufficient, which will also lead to beads in the fiber. It is not recommended to use spinning materials with molecular weight too low.
(7) In the spinning process, what is the reason why the needle tip hangs and floats?
Answer: generally, the spinning environment humidity is too high. The spinning jet absorbs moisture in the air and solidifies in advance, and the charge on the fiber is neutralized, resulting in the decrease of the charged amount of the fiber, resulting in the weakening of the tensile performance of the fiber and the weakening of the electric field force, which is not enough to be adsorbed to the receiving electrode. Try dehumidification with dehumidifier or heat dehumidification.