• Title/Summary/Keyword: Thermosetting resin

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Development of Polymer-Modified Cementitious Self-Leveling Materials for Thin Coat

  • Kim, Wan-Ki;Do, Jeong-Yun;Soh, Yang-Seob
    • KCI Concrete Journal
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    • v.13 no.2
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    • pp.58-66
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    • 2001
  • Recently, polymer-modified mortar has been studied for proposed use on industrial floors as top coat with thin thickness, typically 5~15mm. The purpose of this study is to evaluate basic properties of self-leveling materials using polymer dispersions as kinds of SBR, PAE, St/BA with thin coat (under 3mm). Superplasticizer and thickener have been included in the mixes to reduce bleeding and drying shrinkage as well as to facilitate the workability required. The self-leveling materials using four types of polymer dispersion are prepared with polymer-cement ratio which respectively range from 50% and 75%, and tested for basic characteristics such as unit weight, air content, flow, consistency change and adhesion in tension. From the test results, the self-leveling materials using PAE emulsion at curing age of 28days are almost equal to those of conventional floor using urethane and epoxy resin. The adhesion in tension of self-leveling mortars using SBR latex and PAE emulsion at curing age of 3days is over 17 kgf/cm$^2$(1.67MPa). Consistency change is strongly dependent on the type of polymer dispersion. It is concluded that the self-leveling materials using polymer dispersions can be used in the same manner as conventional floor using thermosetting resin in practical applications, in the selection of polymer dispersions.

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The Change of Degree of Cure and Specific Heat Capacity According to Temperature of Thermoset Resin (열경화성 수지의 온도에 따른 경화도와 비열(Cp) 변화)

  • Shin, Dong-Woo;Hwang, Seong-Soon;Lee, Ho-Sung;Kim, Jin-Won;Choi, Won-Jong
    • Composites Research
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    • v.28 no.3
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    • pp.99-103
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    • 2015
  • This paper presents the cure kinetics studies on the cure reaction of thermosetting resin. Above all, change in degree of cure and specific heat capacity according to temperature are observed using DSC and MDSC. The results are analyzed by cure kinetics and specific heat capacity model. Glass transition temperature was also measured to apply to the specific heat capacity model. Model parameters were gained from the modeling result. As a result, behavior of specific heat capacity can be calculated mathematically.

Electrical and Mechanical Properties of Epoxy/Heterogeneous Inorganic Composites Materials for the Application of Electric Power GIS Appliances (친환경 GIS용 전력기기의 적용을 위한 에폭시 이종무기물 복합재료의 전기적, 기계적 특성)

  • Park, Jae-Jun
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.67 no.12
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    • pp.1633-1640
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    • 2018
  • Epoxy resin is a polar thermosetting polymer that is widely employed in different branches of industry and everyday life, due to their stable physical and chemical properties. Of all the polymer materials currently being used in the electrical insulation industry, epoxy resin is the most widely used kind, chosen as the base polymer material in the present study. Composites were prepared according to the mixing ratio (MS: MA, 1: 9, 3: 7, 5: 5, 7: 3, 9: 1)of mixture for Heterogeneous Minerals(Micro Silica:MS, Micro Alumina:MA) (MS+MA). We have investigated for AC electrical insulation breakdown characteristics and the dielectric properties (permittivity, dielectric loss, and conductivity) with frequency changes. The electrical AC insulation breakdown performance was improved with the increase of the mixing ratio of MS according to heterogeneous mineral material mixture(MS+MA). As Dielectric properties, the dielectric constant and dielectric loss increased with decreasing frequency and decreased with increasing MS content ratio of heterogeneous mineral mixture. Tensile strength and flexural strength according to the mixing ratio (MS + MA) of epoxy / heterogeneous mineral mixture were studied by mechanical properties. The performance of mechanical tensile and flexural strength was significantly improved as the fill contents ratio of MS increased.

Passivation Layer (Thermosetting Film)가 형성된 유기박막 트랜지스터의전기적 특성 변화에 대한 연구

  • Seong, Si-Hyeon;Kim, Gyo-Hyeok;Jeong, Il-Seop
    • Proceedings of the Korean Vacuum Society Conference
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    • 2013.02a
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    • pp.380-380
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    • 2013
  • 본 논문에서는 외기 환경 요인 중에서 H2O와 O2의 영향으로 성능이 저하되는 유기박막트랜지스터(OTFT)의 수명시간 향상을 위하여 필요한 passivation layer의 효과에 대하여 알아 보았다. OTFT에 기존의 액상 공정이나 증착 공정으로 단일 passivation layer또는 다층 passivation layer를 형성하는 방식과는 다르게 향후에 산업 전반에 적용이 기대되는 것을 고려하여 제작 공정의 간편성을 위하여 film 형태로 되어 있는 열경화성 epoxy resin film으로 passivation layer를 구현하는 방법을 사용하여 OTFT의 storage stability를 평가하였다. passivation layer가 없는 OTFT와 열경화성 epoxy resin film으로 passivation된 OTFT의 전기적 특성이 서로 비교 평가되었으며 또한 30일 동안 온도 $25^{\circ}C$ 상대습도 40%의 환경을 갖는 Desicator 안에서 소자를 보관하여 시간에 따른 전기적 특성 변화를 검증하여 epoxy resin film의 passivation layer으로의 적용가능성을 검증하였다. 결과적으로 30일 후의 passivation layer가 없는 OTFT의 전기적 특성은 매우 낮게 떨어진 반면에 epoxy resin film으로 passivation layer가 구현된 OTFT의 mobility는 $0.060cm^2$/Vs, VT는 -0.18 V, on/off ratio는 $3.7{\times}10^3$으로 초기의 소자 특성이 잘 유지되는 결과를 얻었다. OTFT는 Flexible한 polyethersulfone (PES)기판에 게이트 전극이 하부에 있는 Bottom gate 구조로 제작되었고 채널 형성을 위한 유기반도체 재료로 6,13-bis (triisopropylsilylethynyl) (TIPS) pentacene이 사용되었고 spin coating된 Poly-4-vinylphenol (PVP)가 게이트 절연체로 사용되었다. 이때 Au전극은 Shadow mask를 이용하여 증착하였다. 또한 OTFT의 채널 길이 $100{\mu}m$, 채널 폭 $300{\mu}m$의 영역에 Drop casting법을 사용하여 채널을 형성하였다. 물리적 특성은 scanning electron microscopy (SEM), scanning probe microscopy (SPM), x-ray diffraction (XRD)를 사용하여 분석하였고, 전기적 특성은 Keithley-4200을 사용하여 추출하였다.

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A STUDY ON THE CHEMICAL RECYCLING METHOD OF METAL BRACKET (금속(金屬) Bracket의 화학적(化學的) 재생처리(再生處理) 방법(方法)에 관(關)한 연구(硏究))

  • Bang, Sang-Yong;Lee, Dong-Joo
    • The korean journal of orthodontics
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    • v.20 no.1
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    • pp.103-110
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    • 1990
  • Metal brackets were recycled by variable methods for economic reason. Such recycling methods had a great effect on bracket slot width and bonding strength. Therefore, the recycling methods that don't change the properties of original bracket were suggested. In this study, debonded brackets were recycled with 30 kinds of solvents and bracket surfaces were examined by S.E.M. (Super IIIA, ISI International Scientific Instruments, Japan) and Stero Microscope (Sz-Tr, Olympus Tokyo, Japan) methods. The following results were obtained. 1. Thermosetting resin adhesives (eq. $Monolok^{(R)}$, $Concise^{(R)}$) were swelled most in sulfuric acid (assays 95%) and slightly in alcohol groups. 2. The solvent was exchanged every 24 hours during the brackets were recycled with sulfuric acid (assays 95%). As the passage of time, the adhesives were removed more clearly, and after 72 hours adhesives were nearly detached from bracket base. 3. Chemical recycled metal bracket surface showed no irregular structure by S.E.M. method.

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Effects of Interface Porosity on Dielectric and Piezoelectric Properties of BaTiO3-Polymer Composites of O-3 Type Connectivity (O-3형 BaTiO3-폴리머 복합체의 계면기공율 변화에 따른 유전 및 압전특성)

  • 이형규;김호기
    • Journal of the Korean Ceramic Society
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    • v.26 no.5
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    • pp.617-624
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    • 1989
  • Piezoelectric composites of O-3 connectivity were prepared by thermosetting barium titanate-phenolic resin composite under various cruing pressure. Among three kinds of pore in O-3 type ceramic-polymer composite, such as matrix pores, particle pores, and ceramic-polymer interface pores, the effect of interface porosity on the dielectric and piezoelectric constant was investigated. In pure barium titanate ceramics, the porosity factor of dielectric and piezoelectric constants were 5.7 and 5.0, respectively. However, in BaTiO3-polymer composite, the interface porosity factor of the piezoelectric constant was greater than that of the dielectric constant, interface porosity factor b in d33 was 9.8 and in r 4.6. On the other, piezoelectric voltage constant g33 was independent of the porosity of barium titanate ceramics. But in composite system, the piezoelectric voltage constant g33 was decreased with interface porosity.

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Physical remediation of ballast gravels contaminated by oil pollutants (도상자갈 표면 유류 오염물질의 물리적 제거방안 연구)

  • Cho, Young-Min;Lee, Jae-Young;Jung, Woo-Sung;Park, Duck-Shin;Kang, Hae-Sook;Kim, Hee-Man;Lim, Jong-Il
    • Proceedings of the KSR Conference
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    • 2007.11a
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    • pp.1386-1391
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    • 2007
  • The ballast gravels are often contaminated by various pollutants, like diesel fuel, lubricants, and heavy metals. Especially, the gravels near the switching are apt to be polluted by the lubricant. Because this lubricant can pollute the soil of track, the contaminated ballast gravels should be cleaned immediately. In this study, a physical desorption method was used to remove the oil contaminants from the surface of the ballast gravels. Thermosetting resin was used as a media for physical remediation of ballast gravels. The total petroleum hydrocarbon of the gravels was monitored over time. In addition, scanning electron microscopic images were obtained to observe the removal of the oily pollutants from the surface of the gravels.

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Measurement of the Degree of Cure of Thermosetting Resin Matrix Composite Materials (열경화성수지 복합재료의 경화정도의 측정에 관한 연구)

  • 김진수;이대길
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.9
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    • pp.2154-2164
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    • 1995
  • In this study, a dielectric cure monitoring system which consists of an electric circuit, a sensor and a personal computer was developed to on-line monitor the dielectric properties of carbon fiber epoxy composite materials. Also, the kinetic model of carbon fiber epoxy composite materials was developed by curve fitting of differential scanning calorimetry data. The start and end points of cure and the relationship between the dissipation factor and the degree of cure were obtained by comparing the dissipation factor from the dielectric properties with the degree of cure from the DSC data. The relationship between the dissipation factor and the degree of cure was tested under various temperature profiles.

Experimental and microstructural evaluation on mechanical properties of sisal fibre reinforced bio-composites

  • Kumar, B. Ravi;Hariharan, S.S.
    • Steel and Composite Structures
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    • v.33 no.2
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    • pp.299-306
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    • 2019
  • The natural fibre composites are termed as bio-composites. They have shown a promising replacement to the current carbon/glass fibre reinforced composites as environmental friendly materials in specific applications. Natural fibre reinforced composites are potential materials for various engineering applications in automobile, railways, building and Aerospace industry. The natural fibre selected to fabricate the composite material is plant-based fibre e.g., sisal fibre. Sisal fibre is a suitable reinforcement for use in composites on account of its low density, high specific strength, and high hardness. Epoxy is a thermosetting polymer which is used as a resin in natural fibre reinforced composites. Hand lay-up technique was used to fabricate the composites by reinforcing sisal fibres into the epoxy matrix. Composites were prepared with the unidirectional alignment of sisal fibres. Test specimens with different fibre orientations were prepared. The fabricated composites were tested for mechanical properties. Impact test, tensile test, flexural test, hardness test, compression test, and thermal test of composites had been conducted to assess its suitability in industrial applications. Scanning electron microscopy (SEM) test revealed the microstructural information of the fractured surface of composites.

The Recovery of Carbon Fiber from Carbon Fiber Reinforced Epoxy Composites Applied to Railway Vehicles (철도차량용 폐 복합소재로부터 탄소섬유 회수)

  • Lee, Suk-Ho;Kim, Jung-Seok;Lee, Cheul-Kyu;Kim, Yong-Ki;Ju, Chang-Sik
    • Journal of the Korean Society for Railway
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    • v.12 no.6
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    • pp.1059-1066
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    • 2009
  • Recently, the amount of thermosetting plastic wastes has increased with the production of reinforced plastic composites and causes serious environmental problems. The epoxy resins, one of the versatile thermosetting plastics with excellent properties, cannot be melted down and remolded as what is done in the thermoplastic industry. In this research, a series of experiments that decompose epoxy resin and recover carbon fibers from carbon fiber reinforced epoxy composites applied to railway vehicles was performed. We experimentally examined various decomposition processes and compared their decomposition efficiencies and mechanical property of recovered carbon fibers. For the prevention of tangle of recovered carbon fibers, each composites specimen was fixed with a Teflon supporter and no mechanical mixing was applied. Decomposition products were analyzed by scanning electron microscope (SEM), gas chromatography mass spectrometer (GC-MS), and universal testing machine (UTM). Carbon fibers could be completely recovered from decomposition process using nitric acid aqueous solution, liquid-phase thermal cracking and pyrolysis. The tensile strength losses of the recovered carbon fibers were less than 4%.