Preparation And Modification Of Electrospun FK/PVA/PEO Nanofiber Membranes

Keratin is a kind of non-food protein that is renewable,biodegradable,inexpensive,and readily available.Keratin can be found in feather,wool,hair,fingernails,animal claws and horn.But most of them are treated by burning and burying,which not only fails to make full use of keratin resources,but also causes serious pollution to the natural environment.If the keratin resource is reused appropriately,it will bring great social and economic benefits.Chicken feathers keratin(FK)(pre-extracted from chicken feathers by oxidation method)were mixed with poly(vinyl alcohol)(PVA)and poly(ethylene oxide)(PEO).FK/PVA/PEO nanofibrous membranes were fabricated by electrospinning technology.The effects of spinning solution ratio,concentration and electrospinning process parameters on the microstructure of the FK/PVA/PEO nanofibrous membranes were studied.The best electrospinning parameters were as follows: the concentration of spinning solution was 12 %,The mass ratio of PVA to PEO was 70/30,The mass ratio of the sum of quality of PVA and PEO to FK was 80/20,electrospinning applied voltage was 18 kV,receiving distance was 12 cm,flow rate was 0.05 mm/min.The effects of FK content on the microstructure,chemical structure,thermal stability and mechanical properties of the FK/PVA/PEO nanofibrous membranes were studied.TEM,FT-IR and XRD results show that FK,PVA and PEO have good compatibility after blending.Although there was no chemical change after blending the three pure components,the intermolecular hydrogen bonds were formed in the system.And the formation of hydrogen bonds greatly enhanced the compatibility of FK and PVA and PEO.Therefore,the spinnability of FK was improved.The thermal stability of the blend nanofibrous membranes was gradually enhanced with the increase of FK content.However,the mechanical properties of the FK/PVA/PEO nanofibrous decreased gradually.Because FK was a hard protein that had strong brittleness.Based on the fact that the prepared FK/PVA/PEO nanofiber membrane was easy to be lost in water and had poor mechanical properties.The glutaraldehyde which acted as a cross-linker was added into the spinning solution to improve membranes performance.It was found that the morphology of the FK/PVA/PEO nanofibrous membranes did not show any significant differences after crosslinking,but the aldehyde group in glutaraldehyde reacts with the primary amino group of FK and thehydroxyl group in PVA,which results in the increase of molecular chain,the increase of fiber average diameter,and the decrease of interfibrous void ratio.With the increase of glutaraldehyde content,the crystallinity and thermal stability increased gradually.When the content of glutaraldehyde was 15%,the contact angle increased from 21.53°to 86.26°,and the tensile strength increased from 2.62 ±0.51 MPa to 7.28±0.33 MPa.Silver nanoparticles(AgNPs)were prepared by liquid-phase chemical reduction combined with in-situ surface modification,and FK/PVA/PEO nanofiber membranes were modified by AgNPs which could increase the antibacterial performance of FK/PVA/PEO nanofibrous membranes.Silver nanoparticles(AgNPs)was fabricated to modify the FK/PVA/PEO nanofibrous membranes.It was found that,AgNPs coated with polyvinylpyrrolidone(PVP)exhibits uniform sphere shape,and have an average size of 13.67±2.95 nm.With the increase of AgNPs,The average diameter of the nanofibers decreased obviously,when the content of AgNPs was 3%,the average diameter of fiber decreased from 249.76 ±38.02 nm to 160.30 ±25.53 nm.while the thermal stability increased.When the content of AgNPs was 1.2%,the tensile strength and elongation at break reached the maximum,which were 5.52 ±0.71 MPa and 51.50%.The AgNPs induced FK/PVA/PEO nanofibrous membranes showed antibacterial activities,which was better against Gram-negative Escherichia coli(E.coli)microorganism than against Gram-positive Staphylococcus aureus(S.aureus).The FK/PVA/PEO nanofibrous membranes showed increased mechanical and thermal properties,water resistance and antibacterial properties after cross-linking modification and nano modification.Thus they can be applied in biomedical materials,food packaging films and other fields.