• Polymer(Korea)
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• v.26 no.5
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• pp.615-622
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• 2002

Weather-resistant coatings were prepared by mixing a synthesized mill-base and let-down silicone/acrylic resin in weight ratios of 4 : 6, 3 : 7, and 2 : 8. The weatherability of the prepared coatings was tested. The thermal stability, general physical properties, and weatherability of the films of the coatings were improved with silicone content. Among the three mixing ratios mentioned, the ratio of 2 : 8 was the most suitable for the preparation of weather-resistant Coatings. The coatings containing 30 wt% of silicone proved to be a high weather-resistant coating.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.340-341
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• 2008

본 논문에서는 미세 패턴을 구현하기 위해 폴리머 소재의 조성에 따른 공정의 영향에 대해서 연구를 하였다. 제작된 본딩 필름은 난연계 에폭시수지와 고내열 특성을 위해서 경화제 조화 성분 폴리머를 이용하였다. 또한, CTE 값을 향상하기 위해서 필러로서 SiO2 분말을 이용하였다. 조성물은 혼합하여 슬러리를 만들고, 테입 캐스터를 이용하여 필름을 제작하였다. 제작된 필름은 150 및 160도의 온도에서 가열 가압하여 경화하였다. 제작된 수지는 유전율 3.2의 유전율과 loss tan 6값이 0.015값을 나타내었다. 또한 제작된 본딩 필름의 조화특성 연구를 위해서 경화조건, 스웰링 조건, 디스미어 시간에 따른공정 변화의 영향에 대해 고찰하였으며 제작된 시편의 조도는 SEM으로 관찰하여 조화성분 함량에 따른 최적 조건을 선정하였다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.1
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• pp.80-87
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• 2020

The purpose of this study is to investigate the physical properties and self-healing effects of hardener-free epoxy-modified mortars(EMMs) using ground granulated blast furnace slag(GGBFS). The EMMs with GGBFS were prepared with various polymer-binder ratios and GGBFS contents, and tested for strengths, adhesion in tension, water permeation and self-healing effects. The conclusions obtained from the test results are summarized as follows. The compressive strength of the EMMs with GGBFS is reduced with increasing polymer-binder ratios because of reduction of the degree of hardening in the EMMs, and is somewhat inferior to that of unmodified mortars. In the flexural and tensile strengths, the flexural strength of the EMMs is almost constant with increasing polymer-binder ratios. However, the tensile strength of the EMMs is gradually increased with increasing polymer-binder ratios. Regardless of the GGBFS contents, the adhesion in tension of the EMMs increases sharply with increasing polymer-binder ratios. The water permeation of the EMMs is remarkably reduced with increasing polymer-binder ratios and GGBFS contents. The self-healing effect of the hardener-free EMMs with GGBFS is improved with increasing water immersion period at a GGBFS content of 20%.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.3
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• pp.330-337
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• 2021

3D printing is not only at the fundamental study and small-scale level, but has recently been producing buildings that can be inhabited by people. Buildings require a lot of cost and labor to work on the form work, but if 3D printing is applied to the building, the construction industry is received attention from technologies using 3D printing as it can reduce the construction period and cost. 3D printing technology for buildings can be divided into structural and non-structural materials, of which 3D printing is applied to non-structural materials. Because 3D printing needs to be additive manufacturing, control such as curing speed and workability is needed. Since cement mortar has a large shrinkage due to evaporation of water, cement polymer dispersion is used to improve the hardening speed, workability, and adhesion strength. The addition of polymer dispersion to cement mortar improves the tensile strength and brittleness between the cement hydrate and the polymer film. Cement mortar using polymer materials can be additive manufacturing but it has limited height that can be additive manufacturing due to its high density. When light-weight materials are mixed with polymer cement mortar, the density of polymer cement mortar is lowered and the height of additive manufacturing, so it is essential to use light-weight materials. However, the use of EVA redispersible polymer powder and light-weight materials, additional damage such as cracks in cement mortar can occur at high temperatures such as fires. This study produced a test specimen incorporating light-weight materials and EVA redispersible polymer powder to produce exterior building materials using 3D printing, and examined flame resistance performance through water absorption rate, length change rate, and cone calorimeter test and non-flammable test. From the test result, the test specimen using silica sand and light-weight aggregate showed good flame resistance performance, and if the EVA redispersible polymer powder is applied below 5%, it shows good flame resistance performance.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05b
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• pp.15-18
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• 2004

피뢰기에 뇌 또는 이상전압과 같은 정격이상의 고장전류가 유입되어 발생하게 되는 순간적인 열 충격과 내부압력 상승은 폭탄이 내부에서 터지는 것과 같은 엄청난 양의 충격에너지이다. 본 연구에 있어서 폴리머 피뢰기의 제조에 사용된 모듈용 브레이드 복합재료는 압력해소 및 폭발 비산하지 않도록 하는 기능을 수행하도록 설계되어있다. 기존의 폴리머 피뢰기에 적용된 복합재료보다 충격에너지를 흡수하는 구조물에 유리한 브레이드 복합재료를 피뢰기 모듈의 제조에 도입한 것은 매우 의미 있는 일이라 판단된다. 따라서 본 연구에서는 열경화성 브레이드 복합재료를 제조하기 위하여 프리폼을 먼저 제작한 다음 금형에 삽입한 후 진공상태에서 수지를 주입하여 경화시키는 RTM공법을 이용하였다. 본 연구의 목적은 브레이드 패턴 및 방압개소 설계 등의 기초적인 자료조사 및 실험을 통하여 폴리머 피뢰기의 폭발 비산을 방지할 수 있는 압력해소 성능을 위한 기초 자료를 확보하고자 하는 것이다. 브레이드 복합재료의 기본적인 경화거동을 등온 및 동적 DSC를 이용하여 고찰하였고, 기본적인 전기적 특성을 평가하였으며, 방압개소를 가진 폴리머 피뢰기 모듈의 고장전류시험시 예상되는 열 충격에 대한 성능을 검증하기 위하여 열팽창계수를 측정하였다.

• Polymer(Korea)
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• v.38 no.2
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• pp.171-179
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• 2014

Low temperature cure prepregs are being developed for use in the preparation of large-structured fiber-reinforced polymer (FRP) composites with good performance. Cure behavior and chemorheology of low temperature cure epoxy resin system, based on epoxy resin, curing agent, and accelerators, were investigated to provide a matrix resin suitable for the prepreg preparation. Characteristics of cure reaction were studied in both dynamic and isothermal conditions by means of differential scanning calorimetry and rheometry. The low temperature cure epoxy resin system suggested in this study as a matrix resin was curable at $80^{\circ}C$ for 3 h, and showed the gel times of 120 and 20 min at 80 and $90^{\circ}C$, respectively. Thermal and mechanical properties of the cured sample were almost the same as high temperature cure counterparts.

• Magazine of the Korea Concrete Institute
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• v.6 no.3
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• pp.131-141
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• 1994

This study was carried out to develop a procedural method to produce high strength polymer concrete using unsaturated polyt.ster resin and to examine its mechanical properties. Various mechanical properties were analyzed with respect to materials and additives. A method to produce high strength polymer concrete was successfully developed. Comperssive strength of $1,291~1,445 kg/cm^2$, splitting tensile strength of $106~145 kg/cm^2$ and flexural strength of $182~235 kg/cm^2$, at age of 7days wer-e achieved from the cylinderical ;md beam specimen prepared with the method. Modulus of elasticity. Poisson's rntio and the ultirnate corn pressive strain of cylinderical specimen were $2.8~3.8{\times}10^5\;kg/cm^2$. 0.21~0.32, and 0.005~0. 0065, respectively. Modulus of elasticity of the polymer concrete was smaller than that of hlgh strength cement concrete while the maximum compressive strain was very larger than that of high strength cement concrete.

• Applied Chemistry for Engineering
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• v.20 no.6
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• pp.622-627
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• 2009

Using an alkali-solution developable photosensitive resin and a carbon black as a conductive filler, photo-patternable pastes for polymer thick film resistor were fabricated and evaluated. A photo solder resist (PSR), which is usually used as protecting layer of printed circuit board (PCB), was used as a photosensitive resin so that ultraviolet exposure and alkali-aqueous solution development of paste were possible. After fabricating the photosensitive polymer resistor paste, the electrical properties of thick film resistors were measured using PCB test boards. Sheet resistance was decreased with increasing amount of carbon black, but the developability was limited in excess loading of carbon black. The sheet resistance was also reduced by re-curing and the change rate was smaller in higher carbon black loading. Moreover, finely patterned meander-type thick film resistors were fabricated using photo-process and large resistance up to several tens of sheet resistance could be obtained in small area by this technique.

• Journal of the Microelectronics and Packaging Society
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• v.13 no.3 s.40
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• pp.39-45
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• 2006

This study was investigated the thermal properties of underfill with various epoxy resins using thermal analysis methods such as differential scanning calorimetry (DSC), thermo gravimetry analysis (TGA), dynamic mechanical analysis (DMA) and thermo-mechanical analysis (TMA). And, the adhesion strength of the underfills/FR-4 substrate was evaluated. The glass transition temperature (Tg) of underfill which was composed the cycolaliphatic epoxy resin was lower than that of underfill which was not composed the cycolaliphatic epoxy resin. The thermal degradation of underfill was composed of two processes, which involved chemical reactions between the degrading polymer and oxygen from the air atmosphere. The coefficient of thermal expansion (CTE) of underfill which was composed the cycolaliphatic epoxy resin was higher than that of underfill which was not composed the cycolaliphatic epoxy resin. The excessive curing temperatures caused a weak boundary layer of epoxy resin, which resulted in a deterioration of mechanical properties in the epoxy resin and thus led to poor adhesion property between the underfill/FR-4 substrate.

• Polymer(Korea)
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• v.25 no.1
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• pp.15-24
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• 2001

In this study, the effects of different glycol molar ratios of unsaturated polyester(UPE) resins on the curing behaviors were investigated. The cross linking process was checked or monitored by differential scanning calorimetry(DSC) and by viscoelastic properties of rigid-body pendulum model. The knife-edge from which the pendulum is suspended, is immersed in a reaction mixture, and the change of the viscoelastic behavior brings on those of the period(T) and logarithmic decrement(${\Delta}$) of the damped free oscillations of the pendulum. The values of T and ${\Delta}$ obtained are related to the dynamic modulus(E') and modulus loss(E'). The information on the viscoelastic behavior of unsaturated polyester(UPE) resins during the curing process are shown to illustrate the usefulness of the techniques. As the content of NPG in a propylene glycol(PG)/NPG glycol mixture increased, both the cycle time during cure and the change of damping during cure of UPE resin decreased.