Preparation Of Electrospun PVDF Nanofiber Membranes With Waterproof And Breathable Performance

Waterproof and breathable fabric is a functional fabric, especially in harsh environment, itcan protect the body from the rain, snow and chemical isolation while passing water vapor to theoutside. As waterproof and breathable fabric developing so fast, it has formed a mature systemwhich can be divided into three categories: coated fabric, woven fabric and laminated fabrics.With the number of waterproof breathable fabric increasing, its scope of application extends fromthe outdoor leisure clothing to the medical and military applications. The performance ofwaterproof breathable fabric finally determines its range of applications. Waterproof breathablefabric used in outdoor sports and leisure clothing,apart from the perfect waterproof breathableperformance, the consumers usually care more about its comfort and protective work wear, suchas doctor and fire fighters who require a higher degree of waterproofing. Fabrics used in militaryfield, such as army uniforms, may be exposed to severe weather conditions, thus, they require agreater degree of barrier performance. To meet the diverse range of end use, it is necessary todevelop materials which can offer different levels of waterproof ability and breathability.Electrospinning is a new technology which can develop a new kind of waterproof breathablefabric with excellent performance. Electrospinning nanofiber with small pore size and porousstructure which can offer a high degree of barrier properties and comfort, it can be used infiltration, tissue engineering scaffold, sensor, protective clothing. Because of the characteristics ofits high surface ratio, light weight, high porosity,it becomes the preferred material for preparinghigh-performance apparel. Polyvinylidene fluoride with high strength in fluorine plastic products,is higher than any other substances. Because PVDF has excellent hydrophobicity and mechanicalproperties, it is used to prepare the waterproof and breathable nanofiber and be tested for itsrelative performance. There is some meaning to do research on nanofibers in the field ofwaterproof and breathable.In this paper, PVDF/CA blend nanofiber membrane has been prepared. Then the bestblending mass ratio of PVDF and CA is90/10which can be determined through a number ofcolumn test analysis (SEM, mechanical properties, waterproof breathable performance).Themembrance has excellent overall performance, whose mechanical properties is better than purespun membrane PVDF. Its breaking strength of4.29MPa and its breaking elongation is48.41percent. And its distribution of pore size is more uniform, with an average pore size of1.551μm.Waterproof and breathable performance are both perfect, its air permeability is27.29mm/s, thewater repellent rating4, hydrostatic pressure is5548Pa.By blending which enhances the mechanical strength hydrostatic pressure value ofmembrance, but it does not improve the softness in this way. In order to make the membrancemore comfort, this paper is try to prepare laminated nanofiber membranes. Laminated spinning is a way to spin multi-layered composite structure film with diverse performance. The results of thesoftness test shows that the bending stiffness of PVDF/PMMA/PVDF is smaller, which aresofter than pure spun PVDF membrane and blended film PVDF/CA(the mass ratio of90/10).Thestrength and elongation of laminated nanofiber membranes is3.02MPa and41.16percent, airpermeability is30.49067mm/s, hydrostatic pressure is4912Pa, test grade of wet performance isthe same as PVDF membrane.Finally, the inorganic nanoparticles has been added in laminated nanofiber membrane’s corelayer, which improves the mechanical properties, waterproof and breathable performance. Byadding an appropriate amount of inorganic nanoparticles in PMMA, the inorganic nanoparticlescan work as a nucleating agent who makes crystallinity more easier. Meanwhile the polar groupsof inorganic nanoparticles and the polar groups of PMMA attract each other, which can enhancethe intermolecular forces. This reduces the differences in the mechanical properties betweenPMMA and the outer layer PVDF, thus making its mechanical performance enhance. When themass fraction of TiO2in PMMA is6percent, the mechanical strength is5.56MPa,breakingelongation is49.95percent, air permeability is20.48433mm/s, resistance to hydrostatic pressurevalue6745Pa,test grade of wet performance is the same as PVDF membrane. Finally, selecting thelaminated film(the content of TiO2is6%) to be subjected to heat treatment in order to furtherimprove its waterproof and breathable ability.