No abstract

No abstract

Nanofiber mats of poly(vinyl chloride) (PVC) and cellulose acetate (CA) encapsulated with silver (Ag) nanoparticles were fabricated via electrospinning for potential use as antimicrobial food packaging materials. 16 wt% PVC was prepared in 1:1 w/w tetrahydrofuran-N,N-dimethylformamide while 16 wt% CA was prepared in 3:2 (w/w) Acetone-N,N-dimethylformamide. Scanning electron microscopy analysis showed that thinner fibers could be electrospun from cellulose acetate as compared to poly(vinyl chloride) at the same solution concentrations with fiber diameters ranging from 70 to 130 nm for cellulose acetate and 180-340 nm for poly(vinyl chloride). Nanofiber diameter reduced with addition and increase of silver nanoparticles from 0 to 1 wt%. Due to the smaller cellulose acetate nanofiber diameter, its mats had lower air permeability rates. Tensile strength tests indicated that the nanofiber mats had marginal to good tensile strength values relative to film based packaging materials. Antimicrobial examination of the nanofiber mats against yeast and mould indicated that there was inhibited growth of the microorganisms on mats containing silver nanoparticles.

No abstract

Nanofiber membranes are extensively used in ultra- and micro-filtration purposes due to their high surface-to-volume ratio. However, nanofiber membranes do not have adequate strength to withstand forces acting on the filter surface, especially when using very low porosity membranes. In this study, PVC nanofiber mats and nanofiber composite membranes were fabricated through electrospinning and solvent casting technology. The membranes were characterized using scanning electron microscopy (SEM), porosimetry, and tensile strength tests. Analysis indicated that electrospun mats contain varying pore sizes (nano to micro) whose frequencies within the mat vary with fiber diameter. It was also established that mats fabricated from low solution concentration contain the largest percentage of pores. The mats’ tensile strength varied with fiber packing density, fiber assembly, and the density of fiber-to-fiber contact points. The tensile properties of the nanofiber composite membranes were found to be between those of the constituents and changed with change in the nanofiber layer thickness. The fabricated nanofiber composite membranes are intended for use in applications such as air ultra-filtration, acoustic filtration etc. The high porosity and small mesh pore size of electrospun nanofiber mats allow for removal of ultra-fine particles or microbes from contaminated air, water or other media.

No abstract

No abstract

The spreading dynamics of small oil drops over nanofiber layers has been investigated to improve the oil spill management process. Although liquid transport studies have been used to compare different substrates, the actual effect of the fibrous substrate structure has not been precisely investigated. Nanofiber substrate structures consist of micro- and nanocapillaries that vary in diameter and length and are interconnected in a complex manner. Migration of a liquid from one layer to another as well as on the same layer is an important part of the sorption process in nanofiber substrate structures. In this work, the problem under investigation provides spreading small oil drops over a thin porous layer nanofiber until saturation. An experimental evolution describing the drop spreading has been deduced, which shows the speed of spread of the oil drop is significantly affected by the substrate areal weight. The oil drop area over a dry porous layer seems to be caused by the interchange of two spreading velocities, one over the layers and the other penetration of the oil drop through the pores of the substrate. The higher the oil spreading speed, the lower the permeation of the oil into the porous nanofiber substrate and vice versa. To increase the absorption of the nanofiber substrate, adding a nonwoven thin film to cover the nanofiber layers was studied. It was revealed that the presence of such film significantly accelerates the oil-drop spreading speed by up to 300% and reduces the overall time of the oil drop's life.