Scientific Background

Asymmetric cellulose acetate (CA) membrane are widely produced by phase inversion method. By a change in the molecular structure of CA polymer; it will act differently while quenching medium drowned in non-solvent bath. A light hydrolysis also oxidation and combination of those subjected to CA powder to claim morphological behavior on the prepared membrane. An FT-IR spectra affirmed deacetylation of CA polymer. Produced membranes are pictured by SEM cross-sectional images to show high porosity after chemical process. Also membranes are prepared to treat Dye/Water solution. Within this section by an ultrafiltration process at 3bar un-like raw CA membrane, chemically modified ones have much more permeation flux (up to 100 L/m2.h) but dye rejection was decreased as a coincident. 

There are many methods for fabricating nanofibers; electrospinning is one of the appropriate and easy method for producing nanofibers. Electrospinning process produce non-woven web that has special properties like large specific surface and small pore size. These properties cause that they have many applications in different fields including protective textiles, medical scaffolding, medical engineering and separating materials like filtration and membrane process. However low mechanical properties of this nanostructure web limited them for some applications. There are various ways to increase mechanical strength. In this study collector drum used with controllable speed to evaluate the effect of fiber alignment on the nanofiber web strength. Various samples were manufactured by changing rotational speed of collector. Fiber alignment and their strength were measured. In this study polyvinyl acetate (PVAc) and polyacrylonitrile (PAN) with different physical properties were electrospun at concentration of 12 wt.%. The results of the tensile test and scanning electron microscope indicate that the alignment and tensile strength were increased with increasing rotational speed of the collector. In PAN samples that have higher glass transition temperature, the increasing of tensile strength is more than the polyvinyl acetate. By increasing collector rotational speed from 0 to 3200 rpm, the strength of web has increased up to 172% that shows fibers are aligned and furthermore polymer chains are oriented.