Image analysis of the luster of fabrics with modified cross-section fibers

We have investigated the luster of modified cross-sectional fiber fabrics as one of the essential quality estimates for clothing development. We have confirmed an objective evaluation method, and have determined the experimental luster characteristics of modified cross-section fibers. The cross-section of the fibers in a fabric affects the appearance of a textile. We used the image analysis method to investigate the luster to determine the critical factors influencing the appearance of modified cross-section fiber fabrics. For similarly structured textiles in a component fabric, clear differences were observed in the fabric weave, density, percentage, and total area of blobs, which is image region. Color played a decisive role in the luster of the textiles, and luster was not significantly influenced by the modified cross-section fabric weave. In addition, the degree of luster did not increase in the order plain to twill to satin for modified cross-sectional fiber fabrics. All the split-type microfibers exhibited higher numerical luster values (percentage of pixels, and number and total area of blobs) than sea-island microfibers did. The degree of luster of the modified cross-sectional fiber fabrics was not high at specular reflection angles.     

Properties of waterborne polyurethane (WBPU) coatings: Effect of alkyl chain length of tertiary amines of carboxylic acid salt groups

Waterborne polyurethane (WBPU) dispersions were prepared via a pre-polymer process using 4,4-dicyclohexylmethane diisocyanate (H₁₂MDI), poly(tetramethyleneoxideglycol) (PTMG), 2,2-dimethylol propionic acid (DMPA), ethylene diamine (EDA), and tertiary amines (TAs) with varying amounts of DMPA and TAs. Three TAs with different alkyl chain lengths were used to neutralize the DMPA carboxylic group: N,N-dimethylbutylamine (DMBA, C4), N,N-dimethylhexylamine (DMHA, C6), and N,N-dimethyloctylamine (DMOA, C8). The structures of the synthesized WBPUs were determined via FT-IR and ¹H NMR spectroscopic techniques. The effects of DMPA and TA content and the TA alkyl chain length on stability of dispersions and properties such as water swelling (%), glass transition temperature (T _g ), tensile strength, binding energy and adhesive strength were investigated. The initial adhesive strength of the intact coatings increased with increasing DMPA and TA content and increasing alkyl chain length of TA. However, after immersion of the coatings in water, the adhesive strength decreased. The maximum adhesive strength under water was observed at a DMPA content of 20.20 mol% with 5.30 wt% DMOA, which has the longest alkyl chain.     

Data transmission textiles for smart clothing using conducting fibers

In this study, electrical properties and data transmission characteristics of 75D PET/silver composite filaments were measured and analyzed in order to explore the feasibility of “digital textiles” in terms of resistance, resonance frequency, dB loss, and Bandwidth. Those characteristics were measured and compared according to measurement length (10～50 cm) and number of strands (1～10) in order to provide a design guide line for smart clothing. According to the measurement results, electrical characteristics of conducting fiber can be enhanced by increasing the number of fiber strand. It was also demonstrated that multiple resonances could occur from conducting fiber when the fiber lengths are varied. Finally, it showed the delay time of conducting fiber reached the saturated value when the number of fiber strand exceeded five.     

Pollution control via a dredged pool at the inlet of a reservoir

We investigated the applicability of a dredged pool formed at the inlet of a reservoir for pollution control. To quantify the effect of a dredged pool on the water quality of a reservoir, we monitored the water quality of the Masan Reservoir, located in the city of Asan, Choongnam Province, Korea, before and after dredging. In addition, a completely mixed box model was applied to simulate the water quality of the dredged pool and reservoir. The model included a water balance equation and chemical mass balance equation, into which several interactions among water quality components, such as phytoplankton, total nitrogen (T-N), total phosphorus (T-P), dissolved oxygen, and chemical oxygen demand (COD), were incorporated. The water quality monitoring and modeling results indicated that reservoir water quality was greatly affected by the dredged pool. The loads of T-N and T-P into the reservoir were reduced by the dredged pool, which may have induced the removal of nutrients by settling. However, the dredged pool may have had a negative effect on the reservoir in terms of COD and chlorophyll-a because of the internal production of organic matter and/or algae with water detention. Therefore, a dredged pool may be used for pollution control in a reservoir, as long as it is combined with measures to reduce concentrations of organic matter and/or algae.     

Flexible VOC sensors using conductive polymers and porous membranes for application to textiles

In order to fabricate textile-based flexible VOC sensors, two conductive polymers such as polyaniline and poly(3,4-ethylenedioxythiophene)-poly(styrene-sulfonate) (PEDOT:PSS) were used as VOC-sensing materials, and various porous organic membranes were used as base substrates on which the conductive polymers were coated. Electrical resistance change of conductive polymers by adsorption of VOCs was measured. Polyaniline showed better sensitivity than PEDOT:PSS. Porous high density polyethylene membrane exhibited the most stable signal reproducibility and dimensional stability of membrane itself. Even after covering with additional high density polyethylene membrane to protect conductive polyaniline inside, the stable signals were still obtained during repeated measurement.     

Synthesis and Biological Evaluation of Carbocyclic Analogues of Pachastrissamine

A series of carbocyclic analogues of naturally-occurring marine sphingolipid pachastrissamine were prepared and biologically evaluated. The analogues were efficiently synthesized via a tandem enyne/diene-ene metathesis reaction as a key step. We found that the analogue 4b exhibited comparable cytotoxicity and more potent inhibitory activity against sphingosine kinases, compared to pachastrissamine. Molecular modeling studies were conducted to provide more detailed insight into the binding mode of 4b in sphingosine kinase. In our docking model, pachastrissamine and 4b were able to effectively bind to the binding pocket of sphingosine kinase 1 as co-crystalized sphingosine. However, 4b showed a hydrophobic interaction with Phe192, which suggests that it contributes to its increased inhibitory activity against sphingosine kinase 1.     

Sound characteristics according to cross-sectional shapes of fibers

In order to investigate the effects of cross-sectional shapes on the sound characteristics of polyester fibers, 10 specimens were woven into a twill structure made of round, hollow, triangular, u-shape, cruciform, and composite cross-sectional (▴/▴, ()/▴,Y y) fibers. Their rustling sounds were recorded, and their sound spectra were obtained from FFT analysis. Physical sound parameters (LPT, ΔL, Δf) and Zwicker’s psychoacoustic parameters of the loudness(Z), sharpness(Z), roughness(Z), and fluctuation strength(Z) were calculated from the sound spectra. According to noncircular cross-section fibers, the hollow shaped fiber had the highest value of LPT, ΔL, loudness(Z), and fluctuation strength(Z). The triangular shaped fiber had a lower value of LPT, ΔL, loudness(Z), and roughness(Z) than those of the round shaped fiber. Among composite cross-section fibers, C1 (▴/▴) and C3 (Y y) had higher values of LPT, ΔL, Δf, and loudness(Z) but C2 (()/▴) had lower values. Also the LPT, ΔL, sharpness(Z), and roughness(Z) values of different denier were similar to each other, but the Δf and loudness(Z) values increased as the denier increased.     

Properties of crosslinked waterborne polyurethane adhesives with modified melamine: Effect of curing time, temperature, and HMMM content

A series of crosslinked waterborne polyurethane (WBPU) adhesives were prepared by prepolymer synthesis. Modified melamine, hexamethoxymethyl melamine (HMMM) was used as the crosslinking agent. It was elucidated by FTIR and ¹H-NMR spectroscopy that the crosslinking reaction occurred between the polyurethane carboxyl acid salt groups and the HMMM methoxy groups. The hydrophobicity of the WBPU films increased after HMMM crosslinking. As the HMMM content was increased (increasing mole ratio of HMMM/dimethylol propionic acid (DMPA)), the water uptake (%) of the film decreased, and the water contact angle increased. The thermal stability, tensile strength, and initial modulus increased with increasing HMMM content up to an optimum value (mole ratio of HMMM/DMPA=0.5) at which point the maximum thermal stability, tensile strength, and initial modulus were recorded. The adhesive strength was found to be dependent on HMMM content, curing time, and temperature. The adhesive strength of crosslinked WBPU in the case of optimum HMMM content (8.46 wt%) was only slightly affected after immersing adhesive bonded nylon fabrics in water (for up to 2 days).