• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.11a
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• pp.4-4
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• 2011

본 연구에서는 해도형 나일론 극세사 제품의 알칼리 용출 및 염색특성에 대한 고찰과 인공피혁, 스웨이드 조직 편물 등의 목적으로 함께 쓰이게 될 폴리우레탄과의 혼방 제품의 염색성 향상에 대한 연구를 진행하였다. 먼저, 해도형 나일론 극세사의 알칼리 용출거동을 확립하기 위해 NaOH 농도 및 온도에 따른 감량 특성을 확인하였으며, Red 색상의 산성염료와 반응성 염료 타입에 따른 염색특성 및 세탁 견뢰도 등을 고찰하였다. 또한, 폴리우레탄의 염착성을 향상시키기 위해 폴리우레탄 합성시 고분자 말단에 아민기를 함유하는 시료에 대한 염색성을 고찰하고, 폴리우레탄 함침 소재로서 쓰이는 인공피혁을 제조하여 염색 특성을 알아보았다. 해당 연구를 통하여 다음과 같은 결과를 얻을 수 있었다. 해도형 초극세사의 알칼리 용출의 경우 $90^{\circ}C$에서 30분 유지시키는 것이 가장 적절한 조건이었으며, pH에 따른 염색성의 경우 레벨링 타입 염료와 반응성 염료의 경우 4~5, 밀링 타입과 함금속 염료의 경우는 5~6정도의 pH에서 우수한 염색성을 나타내었다. 산성염료의 경우 염색온도와 시간이 증가함에 따라 초극세사에 염착된 염료들은 이면의 일반 나일론사로 이동하는 현상이 증가하였지만 반응성 염료의 경우는 이러한 이염 현상이 나타나지 않았다. 한편, 농도가 증가함에 따라 산성염료는 우수한 빌드업성을 나타내는데 반해 반응성 염료는 4% owf이상에서는 염착량이 증가하지 않았으나, 세탁 견뢰도의 경우 반응성 염료로 염색된 시료가 가장 우수한 견뢰도를 나타내었다. 그리고 앞선 모든 염색실험에 있어서 일반 나일론사보다는 초극세사의 염착률이 더 높았고, 겉보기 색농도는 낮게 나타나는 현상을 확인할 수 있었다. 한편, 나일론/폴리우레탄 혼방제품에서 쓰이는 일반적인 폴리우레탄(RPU)과 아민 함량이 높은 폴리우레탄(APU)의 염색성을 알아본 결과 APU의 염색성이 훨씬 우수하였고, RPU에서 나타나는 현상인 염색의 진행에 따른 염료의 탈리가 나타나지 않았으며 견뢰도 또한 우수하였다. 인공피혁의 염색에서는 함침에 사용된 폴리우레탄 수지의 구조에 따라 염색성이 달라지는 현상을 확인하였으며, 특히 반응성 염료를 사용할 경우 인공피혁에서 일반적으로 문제가 되는 견뢰도 저하의 현상이 나타나지 않았다.

• Polymer(Korea)
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• v.29 no.5
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• pp.481-485
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• 2005

In this work, the thermal and mechanical properties of vapor grown carbon nanofibers (VGCNFs)-reinforced difunctional epoxy (EP) composites were investigated in the presence of the 0, 0.1, 0.5, 1.0, and $2wt\%$ VGCNFs. The thermal properties of the VGCNFs/EP composites were studied by thermo-mechanical analysis (TMA) and dynamic mechanical analysis (DMA). The mechanical properties of the VGCNFs/EP composites were also examined by universal testing machine (UTM), falling impact test, and the friction and wear tests. From experimental results, the thermal and mechanical properties of the VGCNFs/EP composites were improved with increasing the VGCNFs contents. This was due to the increase of crosslinking structure of the composites, resulting in improving the mechanical interlockings between VGCNFs and epoxy resins in the present composite system.

• Polymer(Korea)
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• v.24 no.3
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• pp.350-357
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• 2000

Curing behaviors of glass/epoxy prepreg for printed circuit boards (PCB) were studied by using dielectrometer and differential scanning calorimeter. This prepreg was showed the lowest ionic viscosity at about 115$^{\circ}C$, and then the ionic viscosity was gradully increased up to 15$0^{\circ}C$. This indicated that the curing reaction of this prepreg started at 115$^{\circ}C$ and the molecular weight was increased by the accelerated thermal cross-linking reaction. The loss factor and tan $\delta$ values were also measured and discussed. The dielectric behaviors of this prepreg system were also measured according to the cure cycle for PCB. This material was found to be thermally stable up to about 30$0^{\circ}C$ and then was showed an abrupt decomposition beyond this temperature.

• Polymer(Korea)
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• v.31 no.2
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• pp.123-129
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• 2007

Toughening mechanisms and mechanical properties of three different polyolefin-based composite systems we studied using the tensile, Izod impact and double-notch lout-point-bending (DN-4PB) test, which is well known be an effective tool for probing the failure mechanism (s) around the subcritically propagated crack tip. Microscopy observations such as optical microscopy and transmission electron microscopy were carried out lot the test samples. A detailed investigation clearly shows that a variety of toughening mechanisms, i.e., shear yielding, craze, particle-matrix debonding, rubber particle cavitation, crack deflection and bifurcation, are observed around crack tip damage zone. These toughening mechanisms are responsible for the observed, improved fracture toughness. Based on this study, DN-4PB technique is sufficient to obtain the information needed to describe the fracture behavior of polyolefin-based composites as well as their corresponding toughening mechanisms.

• Polymer(Korea)
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• v.31 no.2
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• pp.117-122
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• 2007

In this work, the mechanical and electrical properties, and thermal stability of vapor-grown carbon nanofibers/polyimide (VGCNFs/PI) composite film synthesized by in-situ polymerization were investigated in terms of tensile properties, volume resistivity and thermogravimetric analysis (TGA), respectively. From the results, the addition of VGCNFs with a certain amount into polyimide led to obvious improvement in tensile strength. The volume resistivity of the films was decreased with increasing the VGCNFs content and the electrical percolation threshold appeared between 1 and 3 wt% of VGCNFs content, which was probably caused by the formation of interconnective structures among the VGCNFs in a composite system. The thermal stability of the film was higher than that of pure PI one. This result indicated that the crosslinking of VGCNFs/PI Composites was enhanced by well-distribution of YGCNFs in PI resin, resulting in the increase of the thermal stability of the resulting composites.

• Tribology and Lubricants
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• v.30 no.6
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• pp.343-349
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• 2014

Currently, in order to resist the scratching of the fuel rod surface while fabricating the fuel assembly of the light-water nuclear reactor, we use a solution of nitrocellulose, an explosive material, as a dry lubricant along with its solvent. However, the demand for developing safe and harmless aqueous alternative materials for environment-conservation and field-worker safety has increased. In this study, we demonstrate the preparation of a novel aqueous resin composite using a formulation of aqueous polymeric resin, alcoholic solvent, and water. Subsequently, we characterize this composite on the basis of hardness, adhesive property, and water solubility using plates similar to the fuel rod material. The insertion test of a fuel rod coated with the YS-3 composite shows load values of $18.8-20.5kg/cm^2$, which is comparable with $18.8-20.5kg/cm^2$ of the nitrocellulose coating agent. In addition, the depth and width of longitudinal scratches caused by the YS-3 composite test are 50% higher than those of the standard. We can develop a harmless and safe aqueous dry lubricant to replace the existing NC products through field testing of 264 pieces of fuel rods, after producing 350 kg of the YS-3 prototype. The scratch test for the rod surface showed that weight of chip of YS-3 prototype was smaller than that of NC before and after solvent treatment, indicating the properties of YS-3 prototype was comparable to the counterpart.

• Polymer(Korea)
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• v.33 no.2
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• pp.175-182
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• 2009

Waterborne polyurethanes (WPUs) based on isophorone diisocyanate and mixed polyols of poly(tetramethylene glycol) (PTMG)/polycarbonate diol (PCD) were synthesized. The variation of mechanical and dyeing properties and alkali resistance of the WPU films were analyzed according to the polycarbonate (PC) content. The tensile strength of the films increased and the elongation at break decreased with the PC content in the WPU film. The incorporation of PC component in the WPU film did not affect the alkaline hydrolysis behavior. The synthesized WPU solutions were used as impregnating resins for the production of PET artificial leathers. The prepared WPU resins showed the good color fastness to washing, rubbing, and light of the artificial leather fabrics. The improvement of the properties became greater with the PC content in the WPU resin.

• Composites Research
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• v.35 no.3
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• pp.175-181
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• 2022

Due to the increasing number of wireless communication devices in mmWave frequency bands, there is a high demand for electromagnetic interference (EMI) shielding and heat dissipating materials to avoid device malfunctions. This paper proposes an EMI shielding composite film with a high heat dissipation characteristic. To achieve this, a conductive grid is integrated with a polymer-based composite layer including magnetic and heat dissipating filler materials. A high shielding effectiveness (>40 dB), low reflection shielding effectiveness (<3 dB), high thermal conductivity (>10 W/m·K), thin thickness (<500 ㎛) are simultaneously achieved with a tailored design of composite layer compositions and grid geometries in 5G communication band of 26.5 GHz.

• Korean Chemical Engineering Research
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• v.61 no.1
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• pp.109-115
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• 2023

The extraction and adsorption characteristics for three phenolic ketones with high physicochemical similarity among phenolic compounds, which are alcohol fermentation inhibitors in lignocellulosic biomass hydrolysates, were investigated. The most suitable basic extractant for selectively separating acetosyringone from three phenol ketones by reactive extraction was found to be trioctylphosphine oxide. In addition, it was found that adsorption using XAD16, a polymer neutral resin adsorbent, or physical extraction using hexane, was a suitable separation method for separation of 4'-hydroxyacetophenone (HAP) and acetovanillone (AVO). A five-step fractionation process including extraction and adsorption mentioned above has been first proposed to separate and concentrate the three phenol ketones present at equal mass percentages. When physical extraction with n-hexane and re-extraction with an aqueous NaOH solution were used as the steps 4 and 5 in the fractionation process respectively, it was possible to obtain almost 70% or more of the purity of three phenolic ketones.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.2D
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• pp.209-216
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• 2009

This study was conducted to develop a thin paving technique using polymer epoxy resin materials which is considered as a durable pavement materials. The mechanical performance characteristics of the polymer epoxy resin materials were also evaluated to confirm the validity as a pavement materials. To estimate the performance properties of the materials, bending tests and bonding tests were performed using freeze-thaw and ultra-violet rays to accelerate the aging of materials. In addition, HYUNStay, a commercial structural analysis program for cable-stayed bridges, was used to compare the effect of paving materials between the polymer epoxy resin materials and the conventional ones on the reduction of cable tension and on the stability of the main tower. According to the test results, it is noted that the thin paving technique using polymer epoxy resin materials can improve the performance and durability of pavement compared to the conventional one.