ارتقاء و مدلسازي فرايند توليد نانو الياف بر مبناي ريسندگي الكتروسانتريفيوژ

چكيده انگليسي :

Abstract This study presents a method for the fabrication of ultrafine polymeric nano bers utilizing centrifugal and electrostatic forces simultaneously To reduce the diameter and variability of polyacrylonitrile PAN and poly L lactic acid PLLA nanofibers a unique electro centrifuge spinning device was designed using rotating nozzle and collector whereas the fabrication process spinning head was skillfully sealed from ambient airflow The polymer solution was continuously delivered by a rotating nozzle and the nanofibers were collected by a rotating cylindrical collector at the same rotational speed as the nozzle Field emission scanning electron microscope FESEM results demonstrated that this method has a significant effect on the quality and fineness of nanofibers The diameters of nano bers were controlled by adjusting the rotation speed of spinning head The effect of the rotation speed on the morphology of the nanofibers fabricated by this device was also evaluated In order to provide a useful context for the current nanofiber production method nanofibers obtained in this method were compared with those produced by other methods The results show that air sealed centrifuge electrospinning system ASCES is a facile method for the fabrication nano bers with smaller diameters and high uniform structures The Taguchi method was adopted to optimize the fabrication condition of solid state polymerized polyamide SSP PA66 nanofibers with respect to minimize nanofiber diameter Air sealed centrifuge electrospinning ASCES was used for preparing high quality nanofibers In this study solution concentration rotational speed syringe content and applied voltage were selected as key parameters a ecting the diameter of the fabricated nanofibers The morphology of the electrospun nanofibers was analyzed by using the field emission scanning electron microscope FESEM Nanofiber diameters ranging from 20 to 250 nm were successfully controlled by the Taguchi method and the statistical data based on experimental results indicated that the syringe content and rotational speed had greater in uences 35 76 and 23 93 respectively on nanofiber diameter than did solution concentration and voltage 21 36 and 11 49 respectively Lower syringe content as well as higher rotational speed decreased the nanofiber diameter The minimum concentration decreased the diameter of SSP PA66 nanofibers Also applied voltage had no significant effect on nanofiber diameter Centrifuge spinning suffered from a strong air resistance which leads to a more deflected jet as well as its rapidly solvent evaporation resulting in thicker nanofibers A comparison was drawn between the trajectory of Newtonian jets fabricated by centrifuge spinning and air sealed centrifuge spinning The captured images of the jet trajectory using a high speed camera showed that non isolated jets were more curved than isolated jets due to air resistance A non linear analysis of the Navier Stokes equations was carried out and one dimensional equations were derived using asymptotic techniques The experimental results were compared to numerical solutions of equations There was fairly good agreement between the isolated jet trajectory and the model predicted one but there were differences between the non isolated jet trajectory and the simulation results The non isolated jet curved more compared to the others due to air drag Simulation results showed that decreasing the Rossby number which can be translated to an increase in angular velocity reduced the overall size of the fiber radius contracted the trajectory and increased the tangential velocity and thus the production rates The centrifugal force was increased significantly by increasing the speed of rotation Thus the higher the centrifugal force the greater the extension of polymeric jet which results in thinner ber diameters The simulation provided an insight into the behavior expected during fiber formation with the inclusion of viscosity The influence of the

ولي پوري، افسانه

ارتقاء و مدلسازي فرايند توليد نانو الياف بر مبناي ريسندگي الكتروسانتريفيوژ

مورفولوژي , سيستم ريسندگي الكترو سانتريفيوژ ايزوله شده از هواي محيط , روش تاگوجي , جت مايع خميده , معادلات ناوير- استوكس , آناليز غير خطي , بسط تقريبي