• Transactions on Electrical and Electronic Materials
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• 제16권6호
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• pp.351-354
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• 2015

In this study, alumina plates 9~25 μm in size were used as thermal fillers, and epoxy resin was used as a polymer matrix. Oriented alumina plate/epoxy composites were prepared using a rolling method. The effect of ordering alumina plates increased with alumina plate size. The thermal conductivity and flexural strength of the composites were investigated. The horizontal thermal conductivity of the oriented composite was significantly higher than the vertical thermal conductivity. The horizontal thermal conductivity of the 75 wt% alumina content was 8.78 W/mk, although the vertical thermal conductivity was 1.04 W/mk. Ordering of the alumina plate using a rolling method significantly improved the thermal conductivity in the horizontal direction. The flexural strengths of the ordered alumina/epoxy composites prepared at different curing temperatures were measured.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 추계학술대회 논문집 전기물성,응용부문
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• pp.36-38
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• 2003

In this paper, the surface modificatioin of PDMS (polydimethyl-siloxane) which is a useful material of microfluidic devices is presented. PDMS-based devices can be fabricated by casting the polymer in a mold, but the porosity and the hydrophobicity of PDMS make difficult to use as bio-medical devices. To overcome these disadvantages, the PDMS surface is grafted with HEMA (2-Hydroxyethyle methacrylate) treatments and $O_2$ plasma process. The $O_2$ plasma process is performed for 20 sec after curing PDMS, and PDMS is put in the prepared HEMA without Monomethyle Ether Hydroquinone. Residual monomers and homopolymers of HEMA-treated PDMS surface are removed using soxhlet extractor. The PDMS surface modification using HEHA without Monomethyle Ether Hydroquinone is experimented, and compare to when additing $FeCl_2{\cdot}2H_2O$. A method with a soxhlet extractor compare to the existing rinse method. The hydrophilicity is confirmed by the measurement of a contact angle, and we observe whether the hydrophilicity is retained.

• 한국응용과학기술학회지
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• 제16권2호
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• pp.171-177
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• 1999

The objectives of this study is to investigate the optimum reaction conditions and to identify the product formula in the synthesis of a silicone/acrylic resin that curing in moisture at room temperature. By the addition polymerization of monomers, n-butyl acrylate, methyl methacrylate, n-butyl methacrylate, and 3-methacryloxypropyltrimethoxysilane. a quarter polymer was obtained. Among various initiators investigated in this study, 2.2'-azobisisobutyronitrille was found to be the most suitable initiator. The optimum reaction conditions found in this study are 70 wt% of initial solvent amount, 120 minutes of dropping time, 3 times of initiator addition, $82{\sim}105^{\circ}C$ of reaction temperature, and 8 hrs of reaction time. Also, number average molecular weight of $11700{\sim}33100$ and molecular weight distribution of $1.81{\sim}3.44$ were obtained.

• 한국응용과학기술학회지
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• 제17권1호
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• pp.7-13
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• 2000

Quater polymer(MBHA) containing two types of acrylic functional group, acetoacetoxyethyl methacrylate(AAM) and 2-hydroxyethyl acrylate was prepared. Then, the MBHA was blended with polyisocyanate type Desmodur IL as a curing agent. Thereafter the mixture was cured at room temperature to get high solid acrylic/polyisocyanate. The MBHA was synthesized at $150^{\circ}C$ for 6 hours typically, and the final conversion reached 87-88%. Lowering Tg and increasing AAM amount in the MBHA resulted in high value of conversion. There was no difference in conversion with the variations of OH values. From the results of physical property tests, MIHS coating was proved to be a good automotive top-coating material.

• Korean Chemical Engineering Research
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• 제47권6호
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• pp.669-675
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• 2009

연질 PVC 대체를 위한 비변색 타입의 무용제형 상온 액상수지를 폴리올을 경화제로 사용하는 폴리우레탄수지 구조제어 설계를 통한 프리폴리머 합성방법을 응용하여 제조할 수 있었다. Macro-glycol, 분자량 및 반응조건의 영향 등을 고찰하여 최적의 작업성과 물성을 가지는 무용제형 상온액상수지를 제조하였으며, 우수한 기계적인 특성과 함께 유색작업을 위한 안료의 분산성 등에서도 우수하였고, Tg가 $-40^{\circ}C$의 값을 나타내었다. 또한 자외선 노출이나 질소산화물에 의한 황변특성도 개선할 수 있었다.

• Carbon letters
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• 제25권
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• pp.43-49
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• 2018

This study suggests the novel thermoplastic toughening agent, which can be applied in the monomer forms without increasing the viscosity of the epoxy resin and polymerized during the resin curing. The diazide (p-BAB) and dialkyne (SPB) compounds are synthesized and mixed with the epoxy resin and the carbon fiber reinforced epoxy composites are prepared using vacuum infusion process (VIP). Then, flexural and drop weight tests are performed to evaluate the improvement in the toughness of the prepared composites to investigate the potential of the novel toughening agent. When 10 phr of p-BAB and SPB is added, the flexural properties are improved, maintaining the modulus as well as the toughness is improved. Even with a small amount of polytriazolesulfone polymerized, due to the filtering effect of the solid SPB by the layered carbon fabrics during the VIP, the toughening and strengthening effect were observed from the novel toughening agent, which could be added in monomer forms, p-BAB and SPB. This suggests that the novel toughening agent has a potential to be used for the composites prepared from viscosity sensitive process, such as resin transfer molding and VIP.

• Carbon letters
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• 제14권4호
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• pp.218-227
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• 2013

A supercritical carbon dioxide (SCC) process of dispersion of multi-walled carbon nanotubes (MWCNTs) into epoxy resin has been developed to achieve MWCNT/epoxy composites (CECs) with improved mechanical, thermal, and electrical properties. The synthesis of CECs has been executed at a MWCNT (phr) concentration ranging from 0.1 to 0.3 into epoxy resin (0.1 mol) at 1800 psi, $90^{\circ}C$, and 1500 rpm over 1 h followed by curing of the MWCNT/epoxy formulations with triethylene tetramine (15 phr). The effect of SCC treatment on the qualitative dispersion of MWCNTs at various concentrations into the epoxy has been investigated through spectra analyses and microscopy. The developed SCC assisted process provides a good dispersion of MWCNTs into the epoxy up to a MWCNT concentration of 0.2. The effects of SCC assisted dispersion at various concentrations of MWCNTs on modification of mechanical, thermal, dynamic mechanical thermal, and tribological properties and the electrical conductivity of CECs have been investigated.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 추계학술발표대회 논문집
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• pp.265-268
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• 2002

In this work, the blend system of epoxy and PMR-15 polyimide is investigated in terms of the cure behaviors and thermal stabilities. The cure behaviors are studied in DSC measurements and thermal stabilities are also carried out by TGA analysis. DDM (4, 4'-diamino diphenyl methane) is used as curing agent for EP and the content of PMR-15 is varied within 0, 5, 10, 35, and 20 phr to neat EP. As a result, the cure activation energy ($E_a$) is increased at 10 phr of PMR-15, compared with that of neat EP. From the TGA results of EP/PMR-15 blend system, the thermal stabilities based in the initial decomposed temperature (IDT) and integral procedural decomposition temperature (IPDT) are increased with increasing the PMR-15 content. The fracture toughness, measured in the context of critical stress intensity factor ($K_{IC}$) and critical strain energy release rate ($G_{IC}$), shows a similar behavior with $E_a$. This result is probably due to the crosslinking developed by the interactions between intermolecules in the polymer chains.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 1999년도 추계학술발표대회 논문집
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• pp.73-76
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• 1999

Near infrared spectroscopy techniques were used to study the cure reactions of epoxy resin system based on diglycidyl ether of bisphenol A(DGEBA) resins cured with 4, 4' diaminodiphenyl sulfone (DDS) hardner. Stoichiometric DGEBA/DDS resin formulation was involved in this study. The infrared absorption spectra of the prepared formulation were obtained on an FTIR spectrometer operating in the region of 11000 to 4000$cm^{-l}$. The chemical group peaks of interest in a DFEBA/DDS spectrum were identified by a comparative study with individual spectra of DGEBA and DDS monomers. Where necessary, special model compounds were used to identify unknown bands, such as the primary amine band at 4535$cm^{-l}$. The absorption bands of interest were integrated to quantify the areas and then converted to molar concentrations. This series of quantitative analyses of the major chemical groups led us to understand not only the reaction mechanism but also the cure kinetics. In this paper, the reaction mechanisms observed in stoichiometric DGEBA/DDS resin formulation and the various properties of the resin system as a function of cure temperature are described.

• Composites Research
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• 제27권6호
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• pp.231-235
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• 2014

오토클레이브 성형은 성형제품의 품질은 우수하나 생산비용이 비싸다는 단점이 있다. 생산비용 중에서도 큰 비중을 차지하는 것이 성형툴의 제작공정이다. 따라서 본 연구에서는 생산비용 절감을 위한 선행 연구로서 성형툴의 재질 및 표면상태에 따라 L-shape 제품의 성형후 Spring-in을 Abaqus user subroutine을 이용하여 계산하였고, 열팽창계수와 마찰계수에 따른 결과를 나타내었다. 또한 성형툴 제작시 재질 및 표면상태의 기준점을 제시하여 생산비용을 줄이는데 기여하고자 한다.