Preparation Of Centrifugal Electrospinning Nanofibers And Their Application In Air Filtration Materials

Nanofibers are widely used in energy storage,air filtration,and tissue engineering because of their small size and easy functional modification.Electrospinning to prepare nanofibers has diversity,but its shortcomings of low yield can no longer meet the growing demand for nanofibers.Although centrifugal spinning has high spinning efficiency,the prepared fiber has a large diameter and poor fiber performance.Aiming at these two spinning methods,this paper proposes a centrifugal electrospinning method under negative pressure adsorption.A multi-needle rotary spinneret is used as a source for preparing nanofibers in batches,and the spinning jet is drafted based on the combined action of centrifugal force and electrostatic force,and then the fiber collection is improved by a negative pressure absorption receiving device.On this basis,the spinner was upgraded to prepare a composite nanofiber membrane with high efficiency and low resistance.The following aspects are studied:?1?Based on the centrifugal spinning technology and electrospinning technology,a centrifugal electrospinning device under negative pressure adsorption was designed,the various components of the device were improved,and the experimental verification of the spinnability of the device.The study found that the processed centrifugal electrospinning device can operate stably for a long time.Using polyacrylonitrile?PAN?as the test spinning material,the prepared PAN nanofibers are smooth and continuous.Compared with the centrifugal electrospinning without applying negative pressure,the fiber diameter is thinner and the fiber yield is higher?6.38 g/h?.In addition,the device has also successfully prepared polymer nanofiber membranes with different spinning solvents,proving that the device is suitable for a variety of polymer spinning.?2?Numerically simulate the electric field and flow field of the centrifugal electrospinning device during the spinning process,combined with the movement trajectory of the spinning jet shot by the high-speed camera after being extruded from the needle mouth.Study the fiber forming process of the centrifugal electrospinning device designed with negative pressure adsorption in this paper.Using PAN as a model polymer,the effect of different conditions on nanofiber formation were studied.It is concluded that:a)Affected by the electrostatic field,the polymer solution forms a charged jet when extruded from the spinneret.Under the action of the electrostatic field,it splits to form fine droplets,and the jet whips to form a Taylor cone,accompanied by inertial force.The action of drawing and thinning moves toward the receiving device.b)The introduction of negative pressure airflow in the receiving device makes the phenomenon of vortex airflow obviously weaken during the spinning process.At the same time,a rotating airflow directed toward the ring-shaped receiving device is formed near the collecting device,which can effectively make the fiber quickly deposit on the receiving plate,and the fiber is not easy to float.c)Using single factor variable experimental methods to study the process parameters,it was found that when the spinning nozzle speed was 3500 r/min,and the negative pressure extraction was 20 L/min,the diameter of the nanofiber is 140.5 nm,and the output of the nanofiber can reach 7.96 g/h.?3?Using the device designed in this paper,the spinning nozzle was improved to prepare PAN/PU&PS composite nanofiber membrane,and to study its filter performance.The study found that under the conditions of spinning solution PAN/PU:PS=1:1,the prepared PAN/PU&PS nanofiber membrane has a fluffy structure,and the thick fiber PS provides good support for the fine fiber PAN/PU.Under the test condition of 32 L/min,when the fiber membrane weight is 1.95 g/m²,the filtration efficiency reaches 88.81%,while the filtration efficiency is only 27.46Pa,and the QF value reaches 0.07662 Pa^-1.The electret particles Si₃N₄ were added to the spinning solution,and it was found that the average pore diameter of the PAN/PU&PS-Si₃N₄ nanofiber membrane was 1.41?m and the maximum porosity was86.42%when the Si₃N₄ concentration was 2%.At this time,the fiber charge storage capacity is the best.After 5 days,the attenuation of the surface charge of the fiber membrane was only 20%,the filtration efficiency of the composite fiber membrane reached 98.05%,the filtration resistance was 34.55 Pa,and the QF value was as high as 0.11209 Pa^-1.On this basis,explore the practical performance of PAN/PU&PS-Si₃N₄?2%?fiber membrane.As the weight of the fiber membrane continues to increase,the filtration efficiency and pressure drop gradually increase.As the air flow rate increases?22 L/min?102 L/min?,the filtration efficiency of the nanofiber membrane gradually decreases,and the filtration resistance gradually increases.But at a wind speed of 92 L/min,it can still maintain more than 95%of the filtration performance,and the filtration resistance is 102 Pa,which proves that the fluffy structure and electret effect can effectively improve the filtration performance.