Research On The Surface Modification Of PBT Used As Leukocyte Filter By UV Excimer Light

PBT melt blown nonwoven leukocyte filter material depending on its resistance to corrosion,low fineness,small aperture and littery structure is widely used in blood filtration.Untreated PBT material is hydrophobic,so using some methods to improve its surface hydrophilicity,shorten its filter time and improve its filtration efficiency is necessary.Traditional methods to modify the surface property of PBT usually have conventional UV radiation,UV excimer laser,Plasma treatment and so on,but all these methods have some defects.Conventional UV radiation due to its low radiation efficiency,slow process doesn't have much practical value.UV excimer laser's high manufacturing cost and small beam region restrict its development.Plasma treatment can be very well for textiles,but its equipment and processing costs are very high.The history of UV excimer light source is only about more than a decade. Comparing to conventional UV radiation and Plasma treatment,this new non-coherent monochromatic light source has many advantages such as high-intensity, a narrow spectral bandwidth of 10nm and low cost in process and equipment.In this paper,PBT meltblown nonwoven was treated by KrCl~* UV excimer light at wavelength of 222nm in two different ways.One is direct irradiation and the other one is grafting after irradiation.The main parameter,surface properties and morphology from untreated and irradiated fabrics were analyzed by Contact Angle, Scanning Electrical Microscope(SEM),Fourier-Transform Infrared Spectroscopy(FT-IR),Capillary Analysis,Electrostatic Analysis and Hemolytic Test.After the work mentioned above,the following results are obtained. (1)Direct irradiation of UV excimer light can improve the surface hydrophilicity of PBT melt blown nonwoven leukocyte filters material.The main mechanism is that irradiation ruptures the ester-bond of the fiber molecule and creats free radicals.The free radicals react with the oxygen and water molecules in the air and form into hydrophilic group.(2)Surface modification initiated by UV excimer light and grafted with AA is feasible. Test shows that copolymerization actually occured on the surface of PBT and the hydrophilicity has been improved.(3)The etching caused by direct irradiation will magnify the aperture.Surface modification initiated by UV excimer light and grafted with AA will demagnify the aperture because of the monomer grafted on the fiber.(4)Both two methods can reduce the surface static especially for the latter one because with the improvement of wettability the material will absorb water molecule from the air.As a result,static on the surface is reduced.(5)Hemolytic Test shows that both methods will not cause hemolysis,so they are qualified and effective measures for the surface modification of leukocyte filters.