Preparation Of Barium Titanate Nanowire/polyvinylidene Fluoride Fiber And Its Piezoelectric Sensor

As a crystalline polymer,polyvinylidene fluoride?PVDF?has excellent mechanical properties,chemical resistance,high elasticity,thermoelectricity,and modular properties.PVDF melt-spun fiber has the characteristics of small diameter,low weight,and high softness.It is suitable for varieties of applications such as micro-transduction devices.However,the PVDF fibers produced by ordinary melt spinning are mostly?crystals in natural cooling crystallization.To optimize the?content in PVDF,fiber modification treatment of heat extrusion and nano-particles doping are needed.Barium titanate?BTO?polycarbonate ceramics have high voltage electrical conversion rate,excellent performances such as ferroelectricity,chips,and withstand voltage.They are widely used in electronic devices such as sensors and actuators.In this paper,BTO nano-fillers were doped into PVDF melt spinning sections to prepare BaTiO₃/PVDF fibers,and piezo-electric sensors based on the finger-shaped electrodes were made to measure the piezoelectric properties of the parallelly arranged PVDF fiber sensors.The research work including:?1?Hydrothermal synthesis was adopted in preparation of Na₂Ti₃O₇nanowires.The optimized parameter includes 9mol/L sodium hydroxide solution,the reaction temperature 200?and time 10 h.The obtained Na₂Ti₃O₇nano-wires have an average diameter of 100 nm and average length of 41?m with an aspect ratio of 210.In the second step,BaTiO₃nanowires were synthesized by a displacement reaction between Na₂Ti₃O₇nano-wires and Ba?OH?₂solution.The research successfully prepared BaTiO₃nanowires with an average diameter of 155 nm,a length of 8?m,and an average aspect ratio of 53.?2?BaTiO₃ nano-filler is used as?-phase inducer agent in PVDF melt-spinning,which can increase the volume content of?-phase in the fiber.The effects of BaTiO₃content,spinning drawing ratio,subsequent thermal extruding ratio,thermal extruding rate,and strength on the crystal structure of BaTiO₃substituted PVDF fibers were studied.The optimized process parameters:BaTiO₃content is 1wt.%,1.5 times spinning drawing ratio,5.5 times thermal extruding ratio,40 mm/min thermal extruding rate,18 k V electric field intensity,61.3%crystalline crystals and 95.5%?crystals.?3?A flexible piezo-electric sensor is assembled based on the finger-shaped electrode with the substrate of polyimide?PI?.The fibers are arranged in parallel and the sealed by PET film.The effects of thermally polarized BaTiO₃/PVDF fibers on piezoelectric properties were experimentally analyzed.The relationship between the piezoelectric signals and parameters including polarization time,temperature and electric field were revealed.Applications of BaTiO₃/PVDF fiber piezo-electric sensors were developed.It is concluded that the BaTiO₃/PVDF fiber's piezoelectric signal output can reach reaches 670m V compared with that of 522m V after and before the thermal polarization treatment of 60MV/m,90? and 60min.