Effects of blend ratio and heat treatment on the properties of the electrospun poly(ethylene terephthlate) nonwovens

Semicrystalline poly(ethylene terephthalate) (cPET)/amorphous poly(ethylene terephthalate) with isophthalic acid (aPET) blends with 100/0, 75/25, 50/50, 25/75, and 0/100 by weight ratios were dissolved in a mixture of trifluoroacetic acid (TFA)/methylene chloride (MC) (50/50, v/v) and electrospun via the electrospinning technique. Solution properties such as solution viscosity, surface tension and electric conductivity were determined. The solution viscosity slightly decreased as aPET content increased, while there was no difference in surface tension with respect to aPET composition. The characteristics of the electrospun cPET/aPET blend nonwovens were investigated in terms of their morphology, pore size and gas permeability. All these measurements were carried out before and after heat treatment for various blend weight ratios. The average diameter of the fibers decreased with increasing aPET composition due to the decrease in viscosity. Also, the morphology of the electrospun cPET/aPET blend nonwovens was changed by heat treatment. The pore size and pore size distribution varied greatly from a few nanometers to a few microns. The gas permeability after heat treatment was lower than that before heat treatment because of the change of the morphology.     

Dyebath reuse in dyeing of nylon microfiber non-woven fabric with 1:2 metal complex dyes

Dyebath used for metal complex dyeing of nylon microfiber was recycled to reduce the overall amounts of metal complex dyeing effluents. Instead of discharging the dyebath after each dyeing cycle, the residual dyebath was analyzed spectrophotometrically and reconstituted to the required concentration of dyes and auxiliaries. Dyebaths were reused eight times and the CIELAB coordinates of dyed samples were measured after each recycling. Color difference (ΔE*) between the sample dyed in the fresh bath and that from reused dyebath was maintained below 1.5. The levelness and fastness of dyed fabrics from recycled dyebath were not impaired either. Chromium content of each recycled dyebath was similar to that of the first residual dyebath.     

The effect of freezing and aldehydes on the interaction between fish myoglobin and myofibrillar proteins

The interaction between fish myoglobin (Mb) and natural actomyosin (NAM) extracted from fresh and frozen fish was studied. The quantity of soluble Mb in Mb-NAM extracted was less in frozen than in fresh fish (P < 0.05). However, no differences were observed in Mb that remained in solution following preparation of Mb-NAM from frozen whole fish vs frozen fillets (P > 0.05). MetMb formation in Mb-NAM was generally greater than that observed in control Mb (P < 0.05); the greatest MetMb content occurred in Mb-NAM extracted from frozen whole fish (P < 0.05). The effect of different aldehyde oxidation products on the interaction between fish Mb and NAM was also studied in vitro. The loss of soluble Mb from NAM:Mb preparations was greater in the presence of hexenal and hexanal (P < 0.05) relative to controls, and the degree of solubility loss varied with aldehyde type. Hexenal caused greater OxyMb oxidation than hexanal (P < 0.05). Whiteness of washed NAM and NAM-Mb mixtures decreased following aldehyde addition (P < 0.05). In the absence of Mb, the Ca2+ -ATPase activity of NAM was lower with added hexenal than with hexanal (P < 0.05). However, no differences in Ca2+ -ATPase activity between hexanal and hexenal-treated samples were observed when Mb was present (P > 0.05). Reducing and nonreducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis analyses suggested that both disulfide and nondisulfide covalent linkages contributed to aldehyde-induced cross-linking between Mb and myofibrillar proteins.