Research On Preparation Of Electrospun Nanofiber Membrane And Its Waterproof And Breathable Behaviors

In recent years,with the gradual improvement of people’s living standards,more and more functional fabrics are favored by people,the typical representative is waterproof and permeable fabric.Waterproof and permeable fabric is called"breathable"fabric,it can prevent the outside water molecules from penetrating into the fabric,and the sweat produced by the human body in the form of water vapor through the fabric is smoothly discharged,so as to ensure the comfort of human wearing,which plays an important role in the waterproof and permeable functional membrane core layer.At present,the main methods of producing waterproof and permeable membrane on the market are bidirectional drawing method,melt extrusion,flash method and phase separation method.There are single source of raw materials,high equipment price and complex production process.In addition,most of the current fiber membranes use fluorine-containing raw materials,which are not easy to degrade and have the characteristics of long-distance migration,posing a serious threat to human health and environmental protection.Continuous three-dimensional mesh nanofiber membranes can be prepared by electrospinning,which has the advantages of small pore size,high porosity and large specific surface area.Based on this,this topic selects the water fluorine-free raw material to prepare waterproof and permeable nanofiber membrane by electrostatic spinning technology,and the nanofiber membrane was carried out by hydrophobic modification and mechanical properties modification to acquiring good waterproof performance and excellent mechanical properties.Finally,the waterproof permeable fabric was prepared by laminating the membrane with the ordinary fabric,and the functional modification of the membrane was realized.Firstly,polyvinyl alcohol/polyurethane(PVA/WPU)nanofiber membranes were prepared by electrospinning.Based on single factor test and orthogonal test,with moisture permeability and hydrostatic pressure as the target values,the influence of spinning process on the waterproof and moisture permeability of fiber membrane was studied,and the optimal spinning process was determined.The results showed that the optimal PVA/WPU ratio was 70/30,the total spinning amount was 14 mL,the spinning voltage range was 25-27 kV,the receiving distance was 13-15 cm,and the injection speed was 0.18-0.22 mm/min.In orthogonal test group,the optimal spinning voltage,receiving distance,injection speed,average diameter,CV value and moisture permeability of the fiber membrane were 26 kV,13 cm,0.20 mm/min,172.16 nm,27.61%,7139.056 g/(m~2·24h).The hydrostatic pressure is 8.76 kPa,with excellent moisture permeability.Secondly,the PVA/WPU membrane is studied to solve the problem of insufficient hydrostatic pressure.Polydimethylsiloxane(PDMS)polymer was introduced into the spinning solution to modify the spinning solution,and the optimum spinning process was used to prepare the fiber membrane.The effects of the concentration of hydrophobic agent on the morphology,water resistance and moisture permeability of the fiber membrane were analyzed.The results showed that when the content of hydrophobic agent was 10%,the morphology of the fiber membrane was the best,the roughness of the fiber membrane surface increased,the fiber membrane changed from hydrophilic to hydrophobic,the water contact Angle was 127.75°,the water grade reached 5,the moisture permeability was 6843.429 g/(m~2·24h),and the hydrostatic pressure was 22.56kPa compared with the unmodified one.Increased 13.8 kPa,air permeability is 20.01 mm/s;The breaking strength is 2.62 MPa,the elongation at break is 112.55%,and the fiber membrane has good waterproof and moisture permeability.At the same time,the mechanical properties of the fiber membrane were modified to improve the strength.Based on the hydrophobic modification,polyvinylpyrrolidone(PVP)was added to modify the spinning solution,and the influence of PVP concentration on the morphology,water resistance and moisture permeability of the fiber membrane was analyzed,and the mechanism of PVP mechanical properties modification was explored.The results showed that when the content of PVP was 4%,the morphology of the fiber membrane was the best,and the dense network structure generated by PVP enhanced the mechanical properties of the fiber membrane.The moisture permeability,hydrostatic pressure and fracture strength of the fiber membrane were 6190.106 g/(m~2·24h),24.56 kPa and 5.71 MPa,which were 3.09 MPa higher than before mechanical modification,and the elongation at break was 58.71%.Finally,polyurethane(PUR)hot melt adhesive was used as adhesive,and the base cloth,fiber membrane and lining material were combined by plate hot pressing process to make waterproof and permeable composite fabric.The influence of hot pressing pressure,temperature and time on the waterproof and moisture permeability of composite fabric was analyzed.The results show that the order of influence of three factors of hot pressing process on the comprehensive properties of composite fabric is:hot pressing temperature>hot pressing time>hot pressing pressure,and the best process combination is 30 Pa,150℃,15 s.At this time,the composite fabric moisture permeability of 5679.310 g/(m~2·24h),hydrostatic pressure of 36.61 k P,air permeability of 11.76 mm,peeling strength of 2.92 N/15mm,the comprehensive performance is the best.The"three-in-one"waterproof and moisture permeable composite fabric with high waterproof and moisture permeable and excellent mechanical properties was prepared by this process,and the engineering application of waterproof and moisture permeable nanofiber membrane was realized.