• Title/Summary/Keyword: glass transition temperature$(T_g)$

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Study on volume reduction of radioactive perlite thermal insulation waste by heat treatment with potassium carbonate

  • Chou, Yi-Sin;Singh, Bhupendra;Chen, Yong-Song;Yen, Shi-Chern
    • Nuclear Engineering and Technology
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    • v.54 no.1
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    • pp.220-225
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    • 2022
  • Perlite is one of the major constituents of the radioactive thermal insulation waste (RTIW) originating from nuclear power plants and, for proper waste management, a significant reduction in its volume is required prior to disposal. In this work, the volume reduction of perlite is studied by high-temperature treatment method with using K2CO3 as a flux. The perlite is ground with 0-30 wt% K2CO3, and differential thermal analysis/thermogravimetric analysis is used to monitor the glass transition temperature (Tg) and weight loss. The Tg varied between ~772.2 and 837.1 ℃ with the minima at ~643.5 ℃ with the addition of ~10 wt% K2CO3. It is observed that compared to the pure perlite the volume reduction ratio (VRR) increases with the addition of K2CO3. The VRR of 11.20 is observed with 5 wt% K2CO3 at 700 ℃, as compared to VRR of 5.56 without K2CO3 at 700 ℃. The X-ray photoelectron spectroscopy and scanning electron microscopy are used to characterize perlite samples heat-treated without/with 5 wt% K2CO3 at 700 ℃. Moreover, the atomic absorption spectroscopy indicates that the proposed heat-treatment procedure is able to completely retain the radionuclides present in the perlite RTIW.

A Study on the Thermo-mechanical Characteristics and Adhesion Reliability of Anisotropic Conductive Films Depend on the Curing Methods of Epoxy Resins (에폭시 레진의 경화방법에 따른 이방성 전도필름의 접합신뢰성 및 열적기계적 특성 변화)

  • Gil, Man-Seok;Seo, Kyoung-Won;Kim, Jae-Han;Lee, Jong-Won;Jang, Eun-Hee;Jeong, Do-Yeon;Kim, Su-Ja;Kim, Jeong-Soo
    • Polymer(Korea)
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    • v.34 no.3
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    • pp.191-197
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    • 2010
  • To improve the curing method of anisotropic conductive film (ACF) at low temperature, it was studied to replace the thermal latent curing agent of imidazole compounds by the curing agent of cationically initiating type. Thermo-mechanical properties such as glass transition temperature, storage modulus, and coefficient of thermal expansion were investigated for the analysis of curing behavior. The reliability of ACF were observed in thermal cycle and high temperature-high humidity test. ACF using cationic initiator showed faster curing, lower CTE, and higher $T_g$ than the case of using imidazole curing agent, which is important for the high temperature stability. Furthermore, ACF using cationic initiator maintained a stable contact resistance in reliability test, although it was cured at low temperature and fast rate. With these results, it was confirmed that the curing method of epoxy had great effect on thermo-mechanical properties and reliability of ACF.

Synthesis of Characterization of Poly(alkylene oxide) Copolyols by Catioinc Ring Opening Polymerization and Their Azide Functionalized Copolyols (양이온 개환중합에 의한 폴리알킬렌 옥사이드 코폴리올의 합성과 아지드화 코폴리올의 특성 연구)

  • Lee, Jae-Myung;Seol, Yang-Ho;Kwon, Jung-Ok;Jin, Yong-Hyun;Noh, Si-Tae
    • Applied Chemistry for Engineering
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    • v.31 no.3
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    • pp.267-276
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    • 2020
  • Poly(epichlorohydrin) copolyol series (PECH copolyols) were synthesized via cationic ring-opening copolymerization (ROCP) of oxirane-based monomers and effects of reaction temperature, solvent type, and initiator were studied. As a comonomer, two types of alkylene oxides were used, and polymerization conditions were conducted both with diethylene glycol (DEG) as an initiator in methylene chloride (MC) solvent and tripropylene glycol (TPG) in toluene solvent. In order to induce the active monomer (AM) mechanism in the ring-opening copolymerization reaction, the monomer was injected by an incremental monomer addition (IMA) method using a syringe pump, and the polymerization was performed at -5 ℃. PECH copolyol, a synthesized ephichorohydrin (ECH)-based copolyol, was converted to glycidyl azide-based energy-containing copolyol (GAP copolyol) by azadizing the ECH unit through a substitution reaction. It was confirmed that the synthesized azide copolyol had little effects on changes of the solvent and the initiator. Also, the molecular weight increased 500 after the azide reaction, thereby the GAP copolyol was polymerized as designed. As the content of the comonomer increased, both the Tg and viscosity tended to decrease due to the influence of the alkyl chain length. It is possible to fundamentally prevent CH3N3 amount produced in the azide reaction process, and it is expected that a large-scale process could be achievable.

Preparation and Characterization of Plasticized Poly(vinyl chloride)-g-Poly(oxyethylene methacrylate) Graft Copolymer Electrolyte Membranes (가소화된 Poly(vinyl chloride)-g-Poly(oxyethylene methacrylate) 가지형 고분자 전해질막 제조 및 분석)

  • Seo, Jin-Ah;Koh, Jong-Kwan;Koh, Joo-Hwan;Kim, Jong-Hak
    • Membrane Journal
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    • v.21 no.3
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    • pp.222-228
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    • 2011
  • Poly(vinyl chloride)-g-poly(oxyethylene methacrylate) (PVC-g-POEM) graft copolymer was synthesized via atom transfer radical polymerization (ATRP) and used as an electrolyte for electrochromic device. Plasticized polymer electrolytes were prepared by the introduction of propylene carbonate (PC)/ethylene carbonate (EC) mixture as a plasticizer. The effect of salt was systematically investigated using lithium tetrafluoroborate ($LiBF_4$), lithium perchlorate ($LiClO_4$), lithium iodide (LiI) and lithium bistrifluoromethanesulfonimide (LiTFSI). Wide angle X-ray scattering (WAXS) and differential scanning calorimetry (DSC) measurements showed that the structure and glass transition temperature ($T_g$) of polymer electrolytes were changed due to the coordinative interactions between the ether oxygens of POEM and the lithium salts, as supported by FT-IR spectroscopy. Transmission electron microscopy (TEM) showed that the microphase-separated structure of PVC-g-POEM was not greatly disrupted by the introduction of PC/EC and lithium salt. The plasticized polymer electrolyte was applied to the electrochromic device employing poly(3-hexylthiophene) (P3HT) conducting polymer.

Synthesis of Eco-Friendly High Solid Acrylic Resins and Curing Properties of Acrylic Urethane Resin Coatings (환경 친화형 하이솔리드 아크릴수지의 합성과 아크릴 우레탄 도료의 경화 특성)

  • Kim, Jin-Wook;Lee, Dong-Chan;Choi, Joong-So
    • Korean Chemical Engineering Research
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    • v.55 no.5
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    • pp.586-592
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    • 2017
  • In this study, acrylic resins with solids content of 75% were prepared by addition polymerization of n-butyl acrylate (BA), methyl methacrylate (MMA), 2-hydroxypropyl methacrylate (HPMA) and acetoacetoxyethyl methacrylate (AAEM) monomers. At this time, the glass transition temperature ($T_g$) of the acrylic resin was changed to 20, 30 and $40^{\circ}C$, and the hydroxyl value (OH value) was changed to 60, 90 and 120. As a result, the viscosity of acrylic resin increased with increasing $T_g$ and hydroxyl (OH) value. The synthesized acrylic resin was designed to have a high cross-link density to maintain high elasticity and high durability. The crosslinked acrylic resin was used to prepare an acrylic urethane clear coating by curing reaction with a block isocyanate (Desmodur BL-3175). The physical properties of the clear paints were analyzed by measuring viscosity, adhesion, pencil hardness and $60^{\circ}$ specular gloss. Acrylic urethane clear coatings were prepared as specimens and evaluated for various properties to be applied as top coatings for coil coating. The prepared coatings were excellent in adhesion, excellent in $60^{\circ}$ specular gloss and pencil hardness, and eco-friendly.

Synthesis of Polyurethane Foam/Organonanoclay/Phosphates Composites and its Characterization (폴리우레탄폼/유기나노점토/포스페이트 복합체의 합성과 그 특성)

  • Park, Kyeong-Kyu;Lee, Sang-Ho
    • Elastomers and Composites
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    • v.46 no.4
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    • pp.343-351
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    • 2011
  • We prepared polyurethane foam/cloisite30B/phosphates composites and characterized their rise time, density, cell morphology, and thermal properties. The composites were synthesized with polyadipatediol-cloisite30B composite (f=2.0), polyether-polyol (f=4.6), polymeric 4,4-diphenyl methane diisocyanate (f=2.5), and D-580 (phenyl polyoxyalkenyl phosphate). As a blowing agent, cyclopentane and distilled water were used at various concentrations of D-580 from 0 to 2.81 wt%. The rise times of PUF/Closite30B/Phosphate composites blown with distilled water were faster than those blown with cyclopentane by 30%. The composites blown with cyclopentane had spherical-shape cells and the cell diameter was decreased with increasing D-580 wt%. While $T_g$ of the composites blown with cyclopentane linearly decreased with increasing the D-580 content, the $T_g$ of the composites blown with distilled water increased with the D-580 content. All PUF/Closite30B/Phosphate composites began to decompose from $250^{\circ}C$. The composites blown with cyclopentane showed the second thermal decomposition at temperatures higher than $500^{\circ}C$. The thermal stability of all composites increased with the D-580 content. The effect of D-580 on the thermal stability of the composites was measured higher at the composites blown with distilled water.

Studies on the Thermomechanical Characteristics of the Blend Film of Chitosan/Gelatin (키토산/젤라틴 블랜드 필름의 열적특성에 관한 연구)

  • Kim, Byung-Ho;Park, Jang-Woo;Hong, Ji-Hyang
    • Korean Journal of Food Science and Technology
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    • v.37 no.4
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    • pp.567-573
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    • 2005
  • Compatability of films made of chitosan, gelatin, and their blends prepared by aqueous solution casting was investigated using a thermogravimetric analyzer(TGA) and a dynamic mechanical analyzer (DMA). TGA showed gelatin is more thermally stable than chitosan, and thermal stability of chitosan in blends was higher than that of pure chitosan due to interaction among functional groups of component polymers in blend. Glass transition temperature $(T_g)$ of blends was dependent on chitosan content of blends. Blend films exhibited good miscibility. Moisture and glycerol contents of blend strongly affected thermal properties of two component polymers.

A Study on Physicochemical Properties of Epoxy Coatings for Liner Plate in Nuclear Power Plant (원자력발전소 격납건물 철재면 에폭시 도장시편의 물리화학적 특성 평가)

  • Lee, Jae-Rock;Seo, Min-Kang;Lee, Sang-Kook;Lee, Chul-Woo;Park, Soo-Jin
    • Applied Chemistry for Engineering
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    • v.16 no.6
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    • pp.809-814
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    • 2005
  • In this work, the thermal properties of epoxy coating system on the liner plate in the containment structure of nuclear power plants had been examined by irradiation and design basis accident (DBA) conditions. The effect of immersion in hot water on adhesion strength of the coating system had been also studied. The glass transition temperature ($T_g$) and thermal stability of ET-5290/carbon steel A 32 epoxy coating systems were measured by DSC and TGA analyses, respectively. Contact angle measurements were used to determine the effect of immersion on the surface energetics of epoxy coating system, with a viewpoint of surface free energy. Adhesion tests were also executed to evaluate the adhesion strength at interfaces between carbon steel plate and epoxy resins. As a result, it was found that the irradiation led to an improvement of internal crosslinked structure in cured epoxy systems, resulting in significantly increasing the thermal stability, as well as the $T_g$. Also, the immersion in hot water made a role in the post-curing of epoxy resins and increased the mechanical interlocking of the network system, resulting in increasing the adhesion strength of the epoxy coating system.

Composition-Some Properties Relationships of Non-Alkali Multi-component La2O3-Al2O3-SiO2 Glasses (무알칼리 다성분 La2O3-Al2O3-SiO2 유리의 조성과 몇 가지 물성의 관계)

  • Kang, Eun-Tae;Yang, Tae-Young;Hwang, Jong-Hee
    • Journal of the Korean Ceramic Society
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    • v.48 no.2
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    • pp.127-133
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    • 2011
  • Non-Alkali multicomponent $La_2O_3-Al_2O_3-SiO_2$ glasses has been designed and analyzed on the basis of a mixture design experiment with constraints. Fitted models for thermal expansion coefficient, glass transition temperature, Young's modulus, Shear modulus and density are as follows: ${\alpha}(/^{\circ}C)=8.41{\times}10^{-8}x_1+5.72{\times}10^{-7}x_2+2.13{\times}10^{-7}x_3+1.09{\times}10^{-7}x_4+1.10{\times}10^{-7}x_5+1.15{\times}10^{-7}x_6+2.72{\times}10^{-8}x_7+2.41{\times}10^{-7}x_8-1.08{\times}10^{-8}x_1x_2+4.28{\times}10^{-8}x_3x_7-2.02{\times}10^{-8}x_3x_8-1.60{\times}10^{-8}x_4x_5-2.71{\times}10^{-9}x_4x_8-2.19{\times}10^{-8}x_5x_6-3.89{\times}10^{-8}x_5x_7$ $T_g(^{\circ}C)=7.36x_1+15.35x_2+20.14x_3+8.97x_4+13.85x_5+4.22x_6+28.21x_7-1.44x_8-0.84x_2x_3-0.45x_2x_5-1.64x_2x_7+0.93x_3x_8-1.04x_5x_8-0.48x_6x_8$ $E(GPa)=2.04x_1+14.26x_2-1.22x_3-0.80x_4-2.26x_5-1.67x_6-1.27x_7+3.63x_8-0.24x_1x_2-0.07x_2x_8+0.14x_3x_6-0.68x_3x_8+0.29x_4x_5+1.28x_5x_8$ $G(GPa)=0.35x_1+1.78x_2+1.35x_3+1.87x_4+9.72x_5+29.16x_6-0.99x_7+3.60x_8-0.48x_1x_6-0.50x_2x_5+0.08x_3x_7-0.66x_3x_8+0.94x_5x_8$ ${\rho}(g/cm^3)=0.09x_1+0.51x_2-4.94{\times}10^{-3}x_3-0.03x_4+0.45x_5-0.07x_6-0.10x_7+0.07x_8-9.60{\times}10^{-3}x_1x_2-8.20{\times}10^{-3}x_1x_5+2.17{\times}10^{-3}x_3x_7-0.03x_3x_8+0.05x_5x_8$ The optimal glass composition similar to the thermal expansion coefficient of Si based on these fitted models is $65.53SiO_2{\cdot}25.00Al_2O_3{\cdot}5.00La_2O_3{\cdot}2.07ZrO_2{\cdot}0.70MgO{\cdot}1.70SrO$.

Effects of the Degree of GO Reduction on PC-GO Chemical Reactions and Physical Properties (그래핀 옥사이드(GO)의 환원정도가 PC-GO 화학반응 및 물성에 미치는 영향)

  • Park, Ju Young;Shin, Jin Hwan;Kim, Youn Cheol
    • Applied Chemistry for Engineering
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    • v.26 no.1
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    • pp.53-58
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    • 2015
  • Polycarbonate (PC)/graphene oxide (GO) composites with 3 phr of GO were prepared by using a twin screw extruder at 240, 260, and $280^{\circ}C$ after mixing the solution with chloroform. It was confirmed by DSC and TGA that the glass transition temperature ($T_g$) of PC/GO composites were not changed and the thermal stability was the best in case of the extrusion temperature at $260^{\circ}C$. Thermo mechanical properties of PC/GO composites according to extrusion temperatures were measured by dynamic mechanical analysis (DMA). Storage moduli of PC/GO composites were higher than that of pure PC and there was no detectable changes at varying the extrusion temperature. Based on these results, the extrusion temperature of PC/GO composites was fixed at $260^{\circ}C$. The degree of the chemical reaction of PC/GO composites with respect to the GO reduction time was confirmed by the C-H stretching peak at $3000cm^{-1}$ and the degree of the chemical reaction was similar to that of GO when the reduction time was 1 h. A decrease in the complex viscosity as a function of the GO reduction time was detected by dynamic rheometer, which may be originated from the enhancement of GO dispersion by PC-GO reaction. The GO dispersion was confirmed by scanning electron microscope (SEM).