Preparation And Applications Of Piezoelectric PAN/BaTiO₃ Composite Nanofiber Membranes

Polyacrylonitrile(PAN)has been wildly used in the filter,absorbent and composites materials in daily life.The studies have found that PAN has two molecular conformations(a planar sawtooth conformation and a helical rod conformation),high dipole moment and the potential to be a piezoelectric material.Besides,barium titanate(BaTiO₃)is a typical lead-free piezoelectric material with excellent piezoelectric properties.Therefore,PAN and BaTiO₃were used as raw materials to prepare PAN/BaTiO₃ nanofiber membrane with different BaTiO₃contents by electrospinning in this article.The piezoelectric properties and applications of PAN/BaTiO₃ nanofiber membrane in the composites were explored.At first,different contents of BaTiO₃ nanoparticles(0 wt.%,5 wt.%,10 wt.%,15 wt.%and 20wt.%,respectively)were added to PAN solution with a concentration of 12 wt.%.The PAN/BaTiO₃ composite nanofiber membranes were prepared by electrospinning and the influence of BaTiO₃ nanoparticles on piezoelectric properties of the PAN were tested by an electrochemistry system.After obtaining the optimal added concentration of BaTiO₃,four kinds of nanofiber membranes were manufactured under diverse spinning voltages(10 k V,15k V,20 k V and 25 k V,respectively).The influence of spinning voltage on piezoelectricity of PAN/BaTiO₃ composite nanofiber membranes were analyzed by output voltage,infrared spectroscopy(FTIR)and X-ray diffraction(XRD)tests.Finally,laminated composites were prepared by mixed the nanofiber membranes and carbon cloths.The practical applications of piezoelectric PAN/BaTiO₃ nanofiber membranes in the composite were investigated by modal,interlaminar shear,three-point bending and piezoelectric output tests.The experiment results show that:(1)The addition of BaTiO₃ nanoparticles promoted the transformation from the helical rod conformation to the planar sawtooth conformation in the PAN,and enhanced the piezoelectric performance of PAN.When the content of BaTiO₃ nanoparticles is 15 wt.%,the nanofiber membrane has the greatest piezoelectricity,which the output voltage can reach 9.3 V.(2)The spinning voltage could improve the uniformity of PAN nanofibers and promote the formation of planar sawtooth conformation.When the spinning voltage was 20 k V,the PAN/BaTiO₃ nanofiber membrane has the biggest content of planar sawtooth conformation,leading to the greatest piezoelectricity.(3)PAN/BaTiO₃ nanofiber membrane increases the natural frequency of the composites and improves the interlayer performance.After curing with carbon cloths,the composites still exist piezoelectric properties,and the carbon cloths can export electrical signals well.(4)The composite has good piezoelectric response under the impact of bending stress.At the same time,the damage degree of the composite can be estimated by the change of the output electrical signal,which has achieved the purpose of real-time structure health monitoring of the composite.