Study On The Preparation,Application Of Under-water Superoleophobic Fabric,and Evaluation Of Textile Wettability

With the development of modern society,oil-bearing wastewater produced in the process of transportation of petroleum raw materials and production of industrial products has caused serious harm to the ecological environment.Special wettable materials have excellent effects on oil-water separation because of their wettability to different liquids.At present,most precious metal materials are used to manufacture products,but there are complex preparation methods and other problems,so it is difficult to apply in practice.In this dissertation,low-cost nylon fabrics and non-toxic polyvinyl alcohol（PVA）were selected as basic materials,and under-water superoleophobic fabrics with good practical properties were prepared by the methods which can realize batch preparation.Besides,the current method for the evaluation of textile wettability by spray test method has the problems of strong subjectivity,poor quantification,which is unable to make a reasonable evaluation of the emerging super wetted textiles.The detection and evaluation of textile wettability by using the contact angle and sliding angle methods are studied in this dissertation,which provides a basis for the formulation of the new national standard for the evaluation of textile wettability.The main research contents and results are listed as follows:（1）The surface of nylon fabric was modified by layer by layer self-assembly with polyvinyl alcohol（PVA）,sodium alginate（SA）and calcium carbonate（Ca CO₃）as raw materials.The superhydrophilic/underwater superoleophobic PVA/SA/Ca CO₃ fabric with interpenetrating network gel layer was successfully prepared through this method.The surface roughness of PVA/SA/Ca CO₃ fabric increases,and the contact angle of oil droplets in water can reach more than 155°.In this dissertation,the influence of fabric aperture on oil-water separation efficiency was investigated.The results show that when the pore diameter of the fabric is less than 38μm,the separation efficiency of the oil-water mixture can reach more than 99%,and the separation efficiency still reaches more than 98%after 40 cycles.In addition,after soaking the fabric in ethanol,salt solution,alkali solution and hot water for 72 hours,its oil-water separation efficiency is still over 99%.（2）The nylon fabric surface was modified by one-step impregnation with polyvinyl alcohol（PVA）,sodium silicate（Na₂Si O₃）and nano-silica（nano Si O₂）.Through this method,it successfully has superhydrophilic/underwater superoleophobic properties.The underwater oil contact angle of chloroform on the surface of the fabric prepared by this method can reach 157°.Besides,it has excellent underwater super oil repellency and anti-oil pollution performance,and the separation efficiency still reaches more than 98%after 40 cycles.In addition,the tolerance test shows that the oil-water separation efficiency of PVA/Na₂Si O₃/Si O₂ fabric is still more than 99%after soaking in ethanol,salt solution,acid-base solution and hot water for 72 hours.（3）The wettability of textiles was evaluated by contact angle method and sliding angle method.Through a large number of sample tests results show that when the droplet volume is 5μL,the contact time is 30 s and the proportion of droplet is 1/3,the stable test results can be obtained,and it is reasonable to measure the sliding angle of the fabric with50μL droplet.By comparing the values of contact angle and sliding angle with the wetting method,it is concluded that the fabric has anti wetting property when the contact angle is not less than 120°and the sliding angle is not higher than 40°,and the wetting grade of the fabric is further subdivided according to the angle.