Preparation And Properties Of High Comfort Waterproof And Breathable Nanofiber Fabric

The unique structural designs of waterproof and breathable（WB）nanofiber membranes with nanoscale small diameter,micron aperture and interconnected pores can prevent the penetration of liquid water or contaminant liquid,and allow water vapor to pass through.In recent years,it is favored used in daily protective clothing,building facade,health,water treatment and other fields by researchers.polymer components with different functions can be introduced into polyurethane/fluorinated polyurethane（PU/FPU）nanofibrous membrane matrix materials with outstanding thermal comfort,low surface energy and robust physical and chemical properties,and its WB nanofiber membrane is prepared by electrospinning technology.Then,combined with hot-press composite technology,the high research value of the fiber membrane and base fabric compounded together applied in WB field.In this paper,polyvinylbutyral（PVB）was introduced into PU/FPU spinning solution to prepare PU/FPU/PVB WB nanofiber fabric by electrospinning and hot-press composite technology.On the basis of systematically regulating the relative content of PVB,the physical fusion structure between the fiber membranes was induced by combining with hot-press technology,the mechanical performances of WB membranes are improved by increasing the cohesion and adhesion between the fibers,make the robust breaking strength and elongation at break of the WB nanofiber fabrics reach 89.6 MPa and 48.6%,it is twice the breaking strength and one point five times the breaking elongation of the PU/FPU WB fiber membrane.At the same time,the physical fusion structure produced by heat induction can further reduce the pore size of the fiber membrane without destroying the morphology and structure of the fiber membrane.The water pressure resistance of the WB fiber membrane was greatly increased from 13.5 kPa to 51.6 kPa（anti rainstorm function:water pressure resistance≥35 kPa）,and the water vapor transmittance rate（WVTR）is 7.6 kg m^-2d^-1(anti rainstorm function:WVTR≥2.2 kg m^-2d^-1)It is expected to occupy the high-end market in the field of"respirable"clothing fabrics and meet its diversified application in the fields of general chemical protective clothing,field combat clothing and medical protective clothing.Although the physical welding structure of PU/FPU/PVB WB nanofiber fabric has good waterproofness and excellent thermal comfort,its mechanical performances are still not enough high,which affects the practical application of the fabric.Therefore,combined with the study and analysis of low melting point polymer,based on the preparation of PU/FPU WB nanofiber membrane,low melting point polymer component thermoplastic polyurethane（TPU）was introduced PU/FPU solution by blending.Then,the PU/FPU/TPU WB nanofiber membrane was prepared by electrospinning technology.The PU/FPU/TPU WB nanofiber membrane with physical fusion structure was prepared combination with the characteristics of TPU component melting and hot-press composite technology The mechanical performances of PU/FPU/TPU WB nanofiber fabric could be greatly improved by the physical fusion,and the breaking strength and elongation at break increased to 100.9MPa and 51.5%,respectively.At the same time,the effects of hot pressing temperature and TPU content on the waterproofness and thermal comfort for the PU/FPU/TPU WB nanofiber fabric were also studied.The results show that when the hot-press temperature is120°C and the relative content of TPU is 50 wt%,the PU/FPU/TPU-50 WB nanofiber fabric has high water resistance（60 kPa）and excellent WVTR(8.6 kg m^-2 d^-1).In order to further meet the durability requirements of PU/FPU/TPU-50 WB nanofiber fabric in extreme environment,the waterproofness and mechanical performances need to be further enhanced.Therefore,silane functionalized graphene oxide（FG）with excellent hydrophobicity and mechanical performances was doped into the PU/FPU/TPU-50nanofiber membrane,and combined with hot-press composite.The results show that when the FG concentration is 1.5 wt%,the breaking strength of the optimized PU/FPU/TPU-50/FG-1.5 WB nanofiber fabric was increased to 127.59 MPa,the elongation at break was increased to 70.3%,the water pressure resistance is increased to 80.4 kPa,and the WVTR is also excellent(7.6 kg m^-2 d^-1)The application of PU/FPU/TPU-50/FG-1.5WB nanofiber fabric could meets the waterproofness requirements in extreme environment.