Preparation And Properties Of PTFE Precursor Nanofiber Membrane

In the 21st century,membrane technology,as the most energy-saving and environmentally friendly method,has great potential in water/waste water,chemical industry,catalytic energy storage,electronic industry and other fields.Among them,polytetrafluoroethylene(PTFE)membranes are widely used in the textile industry,filter media,electronics,electrical appliances and construction fields due to their excellent chemical resistance,mechanical,thermal stability and dielectric properties.In recent years,electrospinning technology has been widely used in the preparation of micronanofiber membranes due to its ability to construct ultra-fine nanofibers(high specific surface area)and interconnected micro-nano channels.Therefore,this paper mainly prepares spinning solution by blending PTFE dispersion with polymer spinning aids,and then prepares PTFE precursor nanofiber membranes by electrospinning,and studies its further processing,modification and properties.The main research contents are as follows:Polyethylene oxide(PEO)and polyvinylpyrrolidone(PVP)aqueous solutions were used as carriers to blend with PTFE dispersion,respectively,and electrospinning technology was used to prepare PTFE precursor nanofiber membranes.The effects of the mass ratio of PEO,PVP and PTFE in PEO/PTFE spinning solution and PVP/PTFE spinning solution and spinning parameters on spinnability and fiber morphology were investigated.The experimental results show that PEO has a lower thermal decomposition temperature and can be completely removed during the sintering process,and the PEO/PTFE system is easier to compound with functional nanofillers,thereby expanding the application of PTFE nanofiber membranes(Chapter 3);PVP It has a higher thermal decomposition temperature and is more suitable for the preparation of nanofiber membranes with special structures(Chapter 4).The PEO/PTFE/CNT nanofiber films were prepared by electrospinning technology,and the structure and morphology of PEO/PTFE/CNT nanofibers were regulated by changing the CNT content.By sintering at high temperature,a PTFE/CNT nanofiber film with high conductivity,dielectric and good wave-absorbing properties is obtained.Studies have shown that the PTFE/CNT(5wt.%)nanofiber film has the highest electrical conductivity(1.5S/m),and the PTFE/CNT(1wt.%)nanofiber film has the best reflection loss at a thickness of 2.0mm(-53.2d B).In addition,the PTFE/CNT nanofiber film also exhibits excellent hydrophobicity,lipophilicity,and gas permeability,making it a great potential for practical industrial applications.The PVP/PTFE nanofiber membrane was prepared by electrospinning.The carbon nanofibers(PCNFs)with porous structure were prepared by high temperature carbonization with PTFE as porogen and PVP as carbon fiber precursor by macroscopic and microscopic phase separation method.The research results show that the specific capacitance of 1-2PCNFs(PVP:PTFE=1:2)is 397.14F/g at a current density of 1A/g,and still 262.85F/g at a high current density(16A/g).g.The specific capacitance of 1-2PCNFs is 5 times that of CNFs(PVP:PTFE=1:0).At a current density of 10 A/g,the capacitance retention of 1-2PCNFs still exceeds 100% after 5000 cycles,and the Coulombic efficiency remains above 96.5%.In addition,the prepared PCNFs also have certain flexibility,which makes them have broad application prospects in the field of energy storage.