Study On The Performance Of Waterproof And Moisture Permeable Double-layer Multi-stage Electrospun Polyurethane Nanofiber Membrane

Electrospinning technology is a high-tech method which can directly and continuously prepare nanofibers.Micro/nano-meter multi-level structured materials have been widely used in information,energy,environment and other fields for their high specific surface area and specific structural characteristics,moreover multi-level structure nanofibers prepared by electrospinning also become a hotpot at home and abroad.In the field of protection,waterproof breathable material is a combination of waterproof and moisture permeability of functional fabrics,also known as breathable materials or artificial skin materials.In the special protective clothing and outdoor recreational clothing and other fields play an important role.The purpose of this paper is using conventional electrospinning technology to invent multi-level structured nano fiber membranes which have waterproof and moisture permeable effect as well as clothing comfort,and providing a theoretical and experimental basis for the development of high performance waterproof and moisture permeable materials for our country.This paper is mainly based on the conventional electrospinning technology,using N,N-dimethylformamide(DMF)as the solvent and TPU as the main raw material,followed by the organic branched salt tetrabutylammoniun chloride(TBAC),tree-like TBAC/TPU double-layer nano fiber membrane was prepared by one step method;And basing on the "push-pull effect" principle,a single-level pure TPU and a multi-level tree-like TBAC/TPU double-layer nanofiber membrane were constructed.The surface morphology,element content and thermal properties of the nanofibrous membrane were analyzed by means of SEM,XPS,EDS and TG The effects of the double-layer water-repellent permeability,moisture permeability,filtration,and moisture transport management,etc.of the moisture-permeable film were analyzed too.The results show that the optimum spinning concentration of TPU is 7 wt%,TBAC is 1 wt%,and the optimum spinning concentration of TBAC is 1 wt%.The dendritic structure was the most significant in the electrospinning process at a voltage of 45 kV,a receiving distance of 10 cm and an extrusion rate of 0.5 ml/h.In contrast,the conventional TPU nanofiber membranes have a strong hydrophobic property,whereas the dendritic nanofiber membranes show very high hydrophilic properties.The two-layer composite nano fiber membranes of them exhibited excellent one-way wettability.When the thickness of the TPU layer is 0.04 mm and the thickness of the dendritic TBAC/TPU layer is 0.08 mm,the moisture permeability of the double-layer nano fiber membrane is 2170 g/m2/d,the permeability is 1.16 L/m2/s,the hydrostatic pressure reaches 100 cm Aq,and the filtration efficiency of the fiber membrane is up to 99.95%for the 0.26?m NaCl particles,which can meet the requirements of the protection performance and the comfortable performance of the protective clothing material.