| Electrostatic spinning is an effective and economical method for preparing nanofibers,which can be applied to many kinds of materials.Most of the nanofibers prepared by the traditional electrostatic spinning method are disordered fiber felts,which can be filtered.However,the disordered internal structure also limits the application of nanofiber membrane in some other special fields,such as tissue engineering,optoelectronic devices,and so on.Because of its periodic internal structure,the directional nanofiber membrane can make up for the deficiency of ordinary nanofibers in structure to a certain extent,and widen the application range of nanofibers.At present,there are many methods to prepare aligned nanofibers.By changing the receiving device of electrospinning,controlling electric field and additional magnetic field,we can obtain different kinds of aligned nanofibers,including directional nanofiber films.The applications of aligned nanofibers bundles and yarns,as well as aligned nanofibers coated yarns,are different.In this paper,an effective device for preparing aligned nanofibers membrane is studied.It uses a kind of ladder wide edge device to collect the aligned nanofiber membrane effectively,and then uses Maxwell electric field simulation software.The change of electric field during the deposition of nanofibers was simulated and the stress during the deposition of nanofibers was analyzed.The results show that some of the fibers are decomposed into tensile force and can be further stretched.In this paper,PVDF is used as raw material,electrostatic spinning method and step collecting device are used,which lays a foundation for the application of PVDF nanofiber film in piezoelectric nanogenerator.The effects of different spinning voltage,spinning distance,different concentration and different spinning time on the orientation of nanofibers were studied.The results show that the spinning distance is 12 cm and the voltage is 12 kV.When the concentration of PVDF was 12 wt%,the orientation degree of nanofibers decreased gradually with the increase of spinning time.It was found that 30 min was the best spinning time,and the fiber membrane thickness and orientation degree could be taken into account.Nanogenerators were prepared by PVDF and non-oriented nanofiber films,respectively.The results showed that the output voltage and current of nanogenerators prepared by directional nanofibers were higher than those prepared by non-oriented nanofiber films.The output voltage can reach 1.5V,but the non-directional nanofibermembrane is only 0.6V;Then,the ZnO/PVDF aligned nanofibers were prepared by ZnO nanoparticles doped with 30 nm,and the output voltage was measured.The results showed that the PVDF aligned nanofibers added with ZnO still had good spinnability.However,the addition of ZnO has a certain effect on the orientation quality,the higher the content of ZnO,the worse the orientation quality.Compared with the pure PVDF aligned nanofibers,the output voltage of the aligned nanofibers added with ZnO is tripled.When the doping content of ZnO is 1.5wt%,the output efficiency is the highest,and the output voltage is 3V,and the output voltage is 4.5V when the doped content of ZnO is 1.5wt%.The output current can reach 0.9 ?A.In order to improve the output efficiency of nanogenerator,ZnO/PVDF nanofiber membrane containing 1.5wt% ZnO nanoparticles was prepared by electrostatic spinning.The series nanogenerator and friction piezoelectric hybrid nanogenerator are designed by using the nanofiber film.The mechanical energy can be collected and converted into electric energy.Compared with ordinary piezoelectric generators,series piezoelectric nanogenerators have higher output voltage and output current.The output voltage can reach 6V,and the output current can reach 1.2?A.On the basis of series nanogenerator,friction piezoelectric hybrid nanogenerator is designed.The output voltage and current can be enhanced more,the output voltage can reach 20 V,and the output current can reach 4?A.Because the nanometer generator is pulse output voltage,so the bridge rectifier circuit is introduced,and the capacitor is used to collect the electric energy.When charging the capacitor with the capacity of 2.2?F,the charge quantity is 22?C after charging for5 minutes.The electric energy is 2.12?J.This paper contains 7 tables,32 figures and 73 references. |
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