• 한국염색가공학회지
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• 제25권4호
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• pp.262-270
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• 2013

Temporarily solubilized reactive disperse dyes containing ${\beta}$-sulfatoethylsulfonyl group were applied to 100% meta-aramid knitted fabric and their dyeing properties were investigated. Reactive disperse dyes showed relatively high K/S values on meta-aramid fabric when compared with conventional disperse dye or reactive dye, which showed very low K/S values. Color yields of reactive disperse dyes were highly dependent on dyeing pH and optimum results were obtained at pH 6. Percent exhaustion of reactive disperse dye on meta-aramid fabric was over 80% at 2% o.w.f of dye concentration. Wash fastness of pyridone-based reactive disperse dyes was very good to excellent while that of aminoazobenzene reactive disperse dyes was medium to good. Light fastness of all the reactive disperse dyes was very poor which seems to be due to the low photostability of meta-aramid fiber itself.

• 한국염색가공학회지
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• 제21권4호
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• pp.63-67
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• 2009

m-Aramid dissolved in N,N-dimethylacetamide (DMAc), were coagulated in different coagulants such as water, methanol, ethanol, propanol and butanol. Various concentrations and temperatures of the coagulants were also used to evaluate dyeing properties of coagulated m-aramid films. Field emission scanning electron microscopy (FE-SEM) was employed to investigate the surface morphology of m-aramid films. Wide angle X-ray diffraction (WAXD) was conducted in order to measure crystallinity change of mcaramid fibers and films. WAXD patterns showed that crystallinity of m-aramid fibers was reduced after film formation. In addition, color depth (K/S value) was measured and the results revealed that the film coagulated in water possessed fairly enhanced color depth.

• Advanced Composite Materials
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• 제17권4호
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• pp.333-341
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• 2008

A novel manufacturing method for hybrid composites filled with carbon nanotubes (CNTs) and aramid fibers is proposed. To disperse the CNTs in the epoxy matrix with the presence of aramid fibers, CNT/polyethyleneoxide (PEO) composites are prepared and utilized because PEO is miscible in the epoxy resin. After thin films are made of the CNT/PEO composite and placed together with the aramid fibers, the epoxy resin is infused to them. The PEO is dissolved in the epoxy and then the CNTs are dispersed in the PEO/epoxy matrix between aramid fibers before the pre-heated matrix is cured. It is found that the PEO is completely miscible with the epoxy resin and CNTs are dispersed well in the space between the aramid fibers.

• 한국염색가공학회지
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• 제32권3호
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• pp.128-134
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• 2020

Heat and flame protecting cloth is usually made of meta aramid fiber because of its own properties. But the high inter molecular hydrogen bonding and high Tg is the reason of the difficulty to dye meta aramid fiber. Recently, it was commercialized that the easily dyeable meta aramid fiber(AMD) for improving dyeability. In this study, the dyeing properties of AMD dyed with cationic dyes were investigated. The K/S values of AMD were 5~10% higher than these of general meta aramid fiber(AM) in the case of 1%owf caused by the lower crystallinity of AMD. The difference between K/S values of AMD and AM was increased as increasing dyeing concentration. The washing and rubbing fastness grade of AM and AMD were similar and good to very good.

• 한국염색가공학회지
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• 제35권4호
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• pp.221-230
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• 2023

Meta-aramid and polyamic acid were separated and the manufactured films were analyzed for their integration and logarithmic properties. The miscibility of meta-aramid and polyamic acid was analyzed by Fourier transform infrared spectroscopy and scanning electron microscopy. Using calorimetric analysis and differential scanning calorimetry, the storage of meta-aramid and polyamic acid, indicated on the right side of the column, was analyzed. It was confirmed that the initial thermal resistance occurs because the polyamic acid is accounted for in the meta-aramid, and the glass transition temperature and persistence phenomenon are explained.

• 한국염색가공학회지
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• 제23권3호
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• pp.155-162
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• 2011

para-Aramid has limited dyeability because of its highly crystalline structure and compactness. To improve the dyeability of the para-aramid to reactive dyes of bright color in deep shade, the fabrics were photografted under continuous UV irradiation with dimethylaminopropyl methacrylamide and 4-benzoyl benzoic acid as a monomer and a hydrogen -abstractable photoinitiator respectively. A UV energy of 35J/$cm^2$ and a photoinitiator concentration of ten percent or more with respect to the monomer in the formulation was required for optimal photografting. Grafting yield increased with higher monomer application level. Surface analysis indicated significant alterations in the atomic composition of the photografted fabric surface and the fabric surface was covered with the grafted polymers. While the pristine para-aramid fabrics showed no appreciable dyeability to the ${\alpha}$-bromoacrylamide reactive dyes, the grafted para-aramid fabrics enhanced the dyeability to the reactive dyes substantially. In case of C.I. Reactive Blue 50, a K/S value of 8.7 can be obtained with the grafted para-aramid fabrics with a grafting yield of 2.3 %. Also the color fastness properties of the dyed fabrics was excellent in the conditions of washing, rubbing and light irradiation.

• 한국염색가공학회지
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• 제24권2호
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• pp.131-137
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• 2012

para-Aramid fibers were treated by low-temperature plasma to improve the adhesion. The surface of para-aramid fibers were treated with gaseous plasma of several discharge power and treatment time in oxygen gas at 1Torr pressure. The treated fibers at low-temperature plasma were taken oxygen-containing functional groups and micro-crator on the surface. The modified fibers were measured by dynamic contact angle analyzer and XPS(X-ray photoelectron spectroscopy). The Interfacial adhesion properties of aramid fabric and polyurethane resin were determined by T-peel test. The surface of aramid fibers were observed by FE-SEM photographs. It was found that surface modification and chemical component ratio of the aramid fibers were improved wettability and adhesion characterization.

• Earthquakes and Structures
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• 제7권5호
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• pp.797-815
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• 2014

This research aimed to investigate retrofitting methods for damaged RC columns with SRF (Super Reinforced with Flexibility) and aramid composites and their impacts on the seismic responses. In the first stage, two original (undamaged) column specimens, designed to have a flexural- or shear-controlled failure mechanism, were tested under quasi-static lateral cyclic and constant axial loads to failure. Afterwards, the damaged column specimens were retrofitted, utilizing SRF composites and aramid rods for the flexural-controlled specimen and only SRF composites for the shear-controlled specimen. In the second stage, the retrofitted column specimens were tested again under the same conditions as the first stage. The hysteretic responses such as strength, ductility and energy dissipation were discussed and compared to clarify the specific effects of each retrofitting material on the seismic performances. Generally, SRF composites contributed greatly to the ductility of the specimens, especially for the shear-controlled specimen before retrofitting, in which twice the deformation capacity was obtained in the retrofitted specimen. The shear-controlled specimen also experienced a flexural failure mechanism after retrofitting. In addition, aramid rods moderately fortified the specimen in terms of the maximum shear strength. The maximum strength of the aramid-retrofitted specimen was 12% higher than the specimen without aramid rods. In addition, an analytical modeling of the undamaged specimens was conducted using Response-2000 and Zeus Nonlinear in order to further validate the experimental results.

• 한국염색가공학회지
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• 제30권4호
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• pp.227-236
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• 2018

As consciousness of safety becomes an important social issue, the demand for protective clothing is increasing. Conventional flame-retardant cotton working wear has low durability, and working wear with m-aramid fibers are stiff, heavy, less permeable, and expensive. In this study, recycled m-aramid and cotton have been blended to produce woven fabric of different compositions to enhance high performance and comfort to solve aforementioned problems. The fabrics were analyzed according to constituents and various structural factors. Mechanical properties were measured using KES-FB system. The measured thermal properties are TGA, $Q_{max}$, TPP and RPP. Fabric with polyurethane yarn covered by m-aramid/cotton spun yarn is observed to have good wearability. The fabric of open end spun yarn showed more stiffness than that of ring spun yarn. The sample with the high count of yarn has more smooth surface. In addition, high m-aramid content fabric is considered to have relatively high stiffness when using as clothing. In TGA the fabric with higher m-aramid content showed more stable decomposition behavior. The fabric having rough surface showed lower heat transfer properties in $Q_{max}$. The influence of the fabric thickness was important in convection and radiant heat test.

• Steel and Composite Structures
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• 제31권2호
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• pp.113-123
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• 2019

In this study, carbon fiber/epoxy (CF/EP) composites were interleaved with aramid nonwoven veils with an areal weight density of $8.5g/m^2$ to improve their Mode-I fracture toughness. The control and aramid interleaved CF/EP composite laminates were manufactured by VARTM in a [0]4 configuration. Tensile, three-point bending, compression, interlaminar shear, Charpy impact and Mode-I (DCB) fracture toughness values were determined to evaluate the effects of aramid nonwoven fabrics on the mechanical performance of the CF/EP composites. Thermomechanical behavior of the specimens was investigated by Dynamic Mechanical Analysis (DMA). The results showed that the propagation Mode-I fracture toughness values of CF/EP composites can be significantly improved (by about 72%) using aramid nonwoven fabrics. It was found that the main extrinsic toughening mechanism is aramid microfiber bridging acting behind the crack-tip. The incorporation of these nonwovens also increased interlaminar shear and Charpy impact strength by 10 and 16.5%, respectively. Moreover, it was revealed that the damping ability of the composites increased with the incorporation of aramid nonwoven fabrics in the interlaminar region of composites. On the other hand, they caused a reduction in in-plane mechanical properties due to the reduced carbon fiber volume fraction, increased thickness and void formation in the composites.