• The Journal of Natural Sciences
• /
• v.8 no.2
• /
• pp.21-26
• /
• 1996

Commercially available Chines oriental lacquer was treated to get two fractions, hexane soluble fraction and hexane insoluble fraction. Hexane soluble fraction was subjected to thermal curing process. Films obtained from the lacquer under normal conditions and obtained from thermal curing were compared. The compounds in hexane soluble fraction were copolymerized with 1,6-diisocyanohexane, and toluendiisocyanate(TDI). Films obtained by thermal curing were highly brittle and hydrophobic while the films obtained under normal conditions were hydrophilic. Curing reaction did not occur when oxygen was not available.Some of the major component in the lacquer was isolated by HPLC and UV spectrum of each compound was recorded.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.24 no.5
• /
• pp.84-90
• /
• 2020

The adhesion strength of two konds of solid propellants(primary propellant/secondary propellant) was studied by coating agent of adhesion composition composed of organic solvent, curing agent, and cure catalyst. The coating agent using FeAA, cure catalyst, resulted propellant breaking at more 0.14 wt% and interface breaking at less 0.10 wt%. The TPB cure catalyst of confirmed the result of the interface breaking immediately after curing of the secondary propellant. In addition, the coating agent using TPB was found to increase the adhesion strength between the primary propellant and the secondary propellant over time.

• Journal of the Korea Institute of Building Construction
• /
• v.15 no.1
• /
• pp.25-33
• /
• 2015

In this study, initial crack index was evaluated by FEM analysis to find the crack propagation from hydration heat in precast concrete. As results, as the usage of hardening accelerator increased, initial compressive strength increased and setting time was shortened. Additionally, as amounts of hardening accelerators increased, the central temperature of concrete increased and the time to reach the highest temperature was shortened. It was demonstrated that the hardening accelerators accelerated the hydration reaction of cement, and caused the increase of hydration heat within the short period of time. Furthermore, the crack index for evaluating the heat level was performed by FEM. As results, there was no problem about the cracks, despite of the growth of initial high hydration heat. This is because of the increased tensile strength that is large enough to sustain the thermally induced-stress.

• Journal of Adhesion and Interface
• /
• v.2 no.3
• /
• pp.16-24
• /
• 2001

The curing behavior of a phenolic resin (F/p: 1.3, 1.9, 2.5 for resol resin, F/P: 0.5, 0.7, 0.9 for novolac resin) has been studied by FT-IR spectroscopy. In this study is to synthesis of resol and novolac type phenolic resin with different F/P molar ratios and to compare the level of cure at different curing temperature conditions ($130^{\circ}C$, $160^{\circ}C$, $180^{\circ}C$ for resol resin, $160^{\circ}C$, $170^{\circ}C$, $180^{\circ}C$ for novolac resin) for 3, 5, 7, 10, 20, and 60 (min.), respectively. The conversion (${\alpha}$) was determined by the ratio of the peak area with time to the peak area of non-baked phenolic QH ($3300cm^{-1}$) at spectra. It is concluded that the initial curing rate of resol and novolac resin was increased as the molar ratio of formaldehyde/phenol increased and as the curing temperature of resin increased. According to the analysis was by the homogenous first-order model, the initial curing rate of resol and novolac resin was increased as the molar ratio of formaIdehyde/phenol increased at specific curing temperature.

• Proceedings of the KWS Conference
• /
• 2010.05a
• /
• pp.78-78
• /
• 2010

모바일 정보통신기기를 중심으로 패키지의 초소형화, 고집적화를 위해 플립칩 공법의 적용이 증가되고 있고 있으며 접속피치의 미세화에 따라 솔더 및 언더필을 사용하는 C4 공법보다 ACA(Anisotropic Conductive Adhesive), NCA (Non-conductive Adhesive) 등의 접착제를 이용하는 칩본딩 공법에 대한 요구가 증가하고 있다. 특히, NCA 공법의 경우 산업 현장의 대량생산에 대응하기 위해서는 접착제의 속경화 특성이 요구되어 진다. 일반적으로 접착제의 경화거동은 DSC(Differential Scanning Calorimeter)를 사용해 확인하지만, 수초 이내에 경화되는 접착제의 경우는 적용되기 어렵다. 본 연구에서는 이러한 전자패키지용 접착제의 속경화 거동을 효과적으로 평가할 수 있는 방법을 조사 하였다. 실험에서 사용된 접착제는 에폭시계 레진 기반에 이미다졸계 경화제를 사용한 기본적인 포뮬레이션을 사용하였고, 경화시간은 160^{\circ}C에서 1분 이내에 경화되는 특성을 가지고 있다. 경화 거동을 확인하기 위해서 isothermal DSC와 DEA(Dielectric Analysis)의 두가지 방법을 사용해 비교하였다. 두 실험 방법 모두 $160^{\circ}C$를 유지하며 경화 거동을 확인하였고, DoC(Degree of Cure)의 측정오차를 비교 분석하였다. DEA는 이온 모빌리티 변화에 따른 유전손실율을 측정하는 방법으로 80~90% 이후의 경화도는 측정되지 않았지만, 수초 이내에 경화되는 속경화 특성을 평가하기에 적합한 것으로 확인되었다.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.16 no.6
• /
• pp.278-285
• /
• 2006

Coating mixtures of the resin B-H for the application to the desulfurization system of power plant were coated on carbon steels and cured at the temperature of $65^{\circ}C{\sim}80^{\circ}C$. After being contacted with 70wt% $H_2SO_4$ solution of $100^{\circ}C\;and\;120^{\circ}C$ for several hours, their composition, Vicker's hardness and microstructures by SEM were examined. Corrosion resistance of the coating mixtures to $H_2SO_4$ solution was related to the content of $SO_3$ in the coated specimens after corrosion test. The lower curing temperature and the shorter curing time the coated specimens went through, the higher corrosion resistance to acid they showed, but the more cracks were developed at higher temperature. It was realized that the corrosion resistance to sulfaric acid solution was increased on the condition of curing temperature above $65^{\circ}C$ and curing time above 12 hours at least.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2009.05a
• /
• pp.497-498
• /
• 2009

Unsaturated polyester(UP) and epoxy resin require 8${\sim}$11 hours long harding times and heating systems used by reinforcement liner. This study is to evaluate the effects of low temperature harding property of UP with methyl methacrylate(MMA) monomer mixing proportions.

• Elastomers and Composites
• /
• v.40 no.3
• /
• pp.166-173
• /
• 2005

Effect of thermal aging on the weight loss and water absorption of epoxy adhesives was investigated in the presence of three types of different hardeners, such as D-230, G-5022, and HN-2200. Thermal and mechanical properties of the cured epoxy resins were also studied througth the glass transition temperature and shear adhesion strength measurements. Weight losses of DGEBA/D-230 and DGEBA/HN- 2200 systems were not varied. However, the weight of DGEBA/G-5022 system was significantly decreased with increasing the thermal aging time. The water absorption of the specimens was increased as the thermal aging time increased except that using G-5022. DEGBA/HN-2200 system showed higher $T_g$ value than those of other systems, due to the formation of the fine three-dimensional network structure containing aliphatic ring. Shear adhesion strength of all systems was increased with increasing the thermal aging tine, which is attributed to increased degree of cure and fine three-dimensional network structure formation. And $T_g$ values and shear adhesion strength of all specimens exposed to water was decreased as the immersion time increased.

• Proceedings of the KAIS Fall Conference
• /
• 2006.11a
• /
• pp.269-271
• /
• 2006

Pyromellitic anhydride(PMDA)와 4,4-Oxydianiline(ODA)로부터 Polyimide의 전구체인 Poly(amic acid)(PAA)를 합성하고, 이를 열을 가하여 Polyimide되는 반응을 적외선 분광법을 이용하여 추적하였다. 이미드화 반응은 $175^{\circ}C$에서 1시간, $185^{\circ}C$에서 1시간, $195^{\circ}C$에서 1시간, $215^{\circ}C$에서 1시간, $235^{\circ}C$에서 1시간 경화시킴으로 완결됨을 확인하였다.

• The Korean Journal of Rheology
• /
• v.10 no.2
• /
• pp.92-97
• /
• 1998

열잠재성 경화제인 N-benzylpyrazinium hexafluoroantimonate (BPH)를 이용하여 함 량에 따른 DGEBA계 에폭시 수지의 경화반응에서의 유변학적 특서 및 반응속도를 연구하 였다. 경화시의 활성화 에너지를 Barrett 방법을 이용한 동적 DSC 측정방법으로 조사 하였 다. DSC 실험 결과 BPH의 함량이 증가할수록 활성화 에너지는 감소함을 알수 있었다. Rheomter를 이용하여 DGEBA/BPH 계의 유변학적 특성을 등온경화와 tdmdhsrud화 조건하 에서 살펴보았다. BPH의 함량이 증가함에 따라 겔화점 도달시간 빠르게 나타나는데 이는 낮아진 활성화 에너지에 기인한 것으로 사료된다. 두 번째 damping 피크를 이용하여 유리 화점을 측정하여 Time-Temperature-Transformation (T-T-T) cure diagram을 작성한 결 과 열잠재성 경화제의 특성인 일정온도 이상에서 활성이 나타남을 확인할수있었다.