Study On Preparation Of PTFE Micro/Nano Fiber Membrane By Centrifugal Spinning And Its Properties

With the rapid development of the national economy and industry,the demand for high-performance fibers is also increasing.As a high-performance fiber,polytetrafluoroethylene(PTFE)fiber has excellent chemical resistance,heat resistance,abrasion resistance,aging resistance and high flexural strength.In industrial,medical and health sectors,and high-end technology fields,there are a large number of applications of PTFE fibers,especially in high-temperature gas filtration,oil and water separation,PTFE fibers are widely used.However,because PTFE has a very high melt viscosity and is difficult to dissolve in common solvents,spinning methods such as solution spinning and melt spinning are not suitable for the production and preparation of PTFE fibers.Emulsion spinning(also known as carrier spinning method)can make a PTFE emulsion and a fiber-forming polymer into a blend solution for spinning,and then obtain PTFE fibers through heat treatment.Centrifugal spinning technology has high spinning efficiency and wide raw material adaptability,which can prepare ceramics,metals,composite fibers,high polymer materials,etc.In this paper,polyvinyl alcohol(PVA)and polyvinylpyrrolidone(PVP)used as carriers were blended with PTFE emulsion.By using centrifugal spinning,PTFE micro-nano fiber membranes can be prepared with fiber diameters of tens of nanometers to several microns.The main research contents and conclusions are as follows:In Chapter 2,PVA is used as a carrier,the effects of PVA content,needle size,spinner speed and spinning voltage on spinnability and fiber morphology were studied.When the PVA content increases,the beads on the fiber disappear,and the fiber morphology becomes better.When the PVA content exceeds the critical value,the thickness uniformity of the fiber becomes worse,and the diameter distribution range becomes wider;the needle type increases,the inner diameter of the needle decreases,and the fiber The average diameter of the fiber decreases,and the morphology of the fiber becomes worse as the needle size continues to increase.The larger the spinner speed,the smaller the average fiber diameter and the narrower the diameter distribution range.When the speed exceeds a critical value,the fiber The morphology of the fiber deteriorates;the voltage applied during spinning increases,the diameter of the fiber decreases,and the voltage continues to increase,resulting in jet breakage during spinning,discontinuous spinning,and fiber morphology deterioration.Among them,the content of PVA in the spinning solution has a great influence on fiber formation.The best process parameters for the PTFE/PVA composite micro-nano fibers prepared in this chapter are:PVA content is 7wt%,needle model is 26G,spinner speed is 2000rpm,voltage is 10kV,and average fiber diameter is about 0.35μm.In Chapter 3,the effects of PVP content,needle size,spinner speed,and spinning voltage on the spinnability of PTFE emulsions were studied using PVP as a carrier.When the PVP content is increased,the fiber thickness becomes more uniform and the diameter distribution is more concentrated;the needle size increases,the average fiber diameter decreases,and the needle size continues to increase,the needle is prone to blockage,and discontinuous spinning occurs during jet fracture;As it increases,the average diameter of the fiber gradually decreases,and the diameter distribution range becomes narrower.When the rotation speed exceeds a critical value,the fiber morphology becomes worse;the voltage applied during spinning increases,which is beneficial to the fiber stretching and the fiber diameter changes.Thin,more concentrated fiber diameter distribution.Among them,the content of PVP has a great impact on fiber formation.The optimal process parameters for the PTFE/PVP composite micro-nano fibers prepared in this chapter are:PVP content is 1 lwt%,needle model is 27G,spinner speed is 2500rpm,voltage is 14kV,and average fiber diameter is about 0.62μm.Based on the experiments in the previous two chapters,the effects of high temperature sintering conditions on the morphology,structure and properties of fiber membranes were studied with PTFE/PVA composite micro-nano fiber membranes as the object.The micro-morphology of the sintered fiber membrane was observed,and the effects of different sintering conditions on the fiber diameter,surface water contact angle,pore size,and mechanical properties of the fiber membrane were analyzed.The results show that when the PTFE/PVA composite micro-nano fiber membrane is sintered,the temperature is 370℃ and the sintering time is 20 minutes.The comprehensive performance of the membrane is relatively good.The surface water contact angle is 150.56°,and the average pore diameter is 2.32μm.The breaking strength is 2.23 MPa,and the elongation at break is 47.25%.