Rhodamine dyes have been studied in various scientific areas due to their excellent photophysical properties. In particular, these rhodamine dyes are one of the most famous fluorophores as signal unit in chemosensor study. This is related to spirolactam ring system in rhodamine dyes. When the spirolactam ring is closed, there is nonfluorescence and colorless.
Whereas, ring-opening of the corresponding spirolactam induces strong fluorescence and color. These absorption and emission changes are related to structural changes as well as electron energy potential levels such as HOMO and LUMO values. In this study, two different structures of rhodamine 6G hydrazide depending on the spirolactam ring system were investigated using absorption measurement, electrochemical measurement and computational calculations.
The electrochemical study has been enjoyed in many areas of chemistry. Through this approach using electrochemical measurement, empirical HOMO and LUMO values can be calculated by three methods such as absorption measurement, cyclicvoltammetry and computational calculations. In this study, 1,3-bisdicyanovinylindane was prepared and investigated toward its optical properties. The absorption intensities were changed depending on changes of pH. These absorption changes are induced by resonance form of 1,3-bisdicyanovinylindane. The electron delocalization in π system is related to the resonance form. In according to this electron density distribution and HOMO/LUMO values of 1,3-bisdicyanovinylindane were simulated and calculated by Material Studio 4.3, absorption measurement and cyclicvoltammograms.
The 1,3-bisdicyanovinylindane is one of the most attracted acceptor units in D-π-A system. This attempt is useful to determine more detailed characteristics of the energy potentials.
Poly(acrylonitrile) (PAN) nanofibers containing different amounts of titanium dioxide (TiO2) have been prepared by electrospinning technique. Photocatalytic activity of these electrospun PAN/TiO2 nanofibers and the effect of TiO2 content on the photocatalytic efficiency of PAN/TiO2 nanofibers have been evaluated by monitoring the photodecomposition of fluorescein dye, rhodamine B and methylene blue under UV irradiation with respect to irradiation time. Moreover, the effect of hydrogen peroxide (H2O2) on the photocatalytic behavior of PAN/TiO2 nanofibers has also been investigated. The results showed that PAN/TiO2 nanofibers are effective photocatalyst and their photocatalytic efficiency increases with the increase of TiO2 content in the PAN/TiO2 nanofibers. It is also observed that the presence of H2O2 significantly enhances the photocatalytic ability of PAN/TiO2 nanofibers. The morphology and the photocatalytic behavior of the PAN/TiO2 nanofibers containing different amounts of TiO2 nanoparticles have been investigated by field-emission scanning electron microscopy (FE-SEM) and UV/Visible spectroscopy, respectively.
A new series of anthraquinoid magenta dyes having alkylphenyl substituents was synthesized and applied toward pure polypropylene fibers. The affinity of the dyes toward polypropylene fibers was increased gradually with the increase of the length of alkyl substituents. The optimum length of alkyl group was determined as heptyl substituents from the practical point of view. The color values of the dyes on polypropylene fabrics displayed slight bluish red,namely magenta which is more practical than primary red in color matching. The good fastness ratings to washing,rubbing and light were obtained for the dyes having longer alkyl groups than hexyl substituents. Expecially they exhibited ratings 4 of light fastness, which is higher than primary red dyes previously reported.
The purpose of this study is to fabricate the flame retardant polyester fabric by thermal bonding with low melting component of flame retardant bicomponent filament(LMFRPC) and to describe the characteristics of thermal bonded fabrics. The fabrics were prepared with flame retardant polyester filaments(FRP) as warp and blended filaments of FRP and LMFRPC as weft. The LMFRPC have a sheath and a core wherein the core comprises a flame retardant polyester and the sheath comprises a thermoplastic polyester of low-melting point. In this study, we investigated the physical properties, melting behavior of filament, the effect of the component of FRP and LMFRPC on the thermal bonding, mechanical properties. Melting peak of LMFRPC showed the double melting peak. The thermal bonding of the fabric formed at lower melting peak temperature of bicomponent filament of LMFRPC. The optimum thermal bonding conditions for fabrics was applied at about 170℃ for 60 seconds by pin tenter. On the other hand, the tensile strength,elongation, and LOI of the fabric increased with an increasing component of FRP of weft.
Poly(vinyl alcohol) (PVA)/titanium dioxide (TiO2) composite nanofibers were produced at different TiO2concentrations (0.5, 1 and 1.5 wt.%) using the electrospinning method. The parameters of electrospinning including polymer contents, voltage and tip-to-collector distance (TCD) were optimized for fabrication process. The study showed that 7.5 wt.%PVA, 15 kV applied voltage and 15 cm TCD are the best condition to obtain uniform PVA/TiO2 nanofibers. TiO2nanoparticles give significant effect in fiber morphology. TiO2 content increases the diameter of the fibers and roughen the fiber surfaces. The PVA/TiO2 nanofibers were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD).
Although para-aramid fibers poss higher mechanical properties, they show very low resistance to sunlight exposure. This paper studied on the effect of nano-sol coated TiO2 to improve the photo-stability of p-aramid fibers. Titanium dioxides were prepared by sol-gel method from titanium iso-propoxide at different R ratio (H2O/titanium iso-propoxide). All samples were characterized by XRD, TEM and UV-vis spectrometer. The mechanical properties of p-aramid fabrics by TiO2nano-sol coating before and after sunlight irradiation were measured with tensile tester. XRD pattern of titanium dioxide particles was observed by mixing phase together with rutile and anatase type. The results showed, after sunlight irradiation,the decreased mechanical properties of the fiber. Furthermore, the sunlight irradiation obviously deteriorated the surface and defected areas of the fiber severely by photo-induced chain scission and end group oxidation in air.
A tenter is very important to dry and heat-set fabrics in textile dyeing and finishing industry. However, the tenter machine typically utilizes more than 80% of all the power in dyeing system, and yet is one of the primary machine which affects quality of fabrics. Therefore, performance optimization of the tenter machine is required to reduce energy consumption and enhance quality of fabrics. To optimize the tenter machine, it is important to maintain the uniform flow rate, which can be obtained by optimizing a nozzle geometry. In this study, emboss hole angle was investigated as main parameter in flow rate uniformity and heat flux efficiency. The analysis results were compared with those acquired from bench-scale dryer test in the laboratory. The tenter machine performance simulated by Computational Fluid Dynamics(CFD) was optimized by controlling emboss hole angle.
In order to investigate the mechanical properties of working clothes materials considering industrial settings, the test weaving materials were compared with the existing materials depending on the season. The material design of the test fabrics were changed through fineness, composition, density of materials then subsequently treated with functional finish. As a result of evaluation of the forms according to KES-FB system, Koshi was deduced, and Numeri and Fukurami were increased. Thereby, the test weaving materials became flexible, surface became smoother, elasticity and volume characteristics indicated to have been improved. Consequently, the THV value of working clothes materials for test weaving was increased compared to existing materials which indicated improved result of the total hand value. Specially, the winter cloth material indicated improved drape characteristics and dimensional characteristics, showed improved liveliness as being compressed softly.