• Title, Summary, Keyword: Kissinger method

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Reactions and Properties of a RT-Castable PU Elastomer Modified with Oligomeric Diol (올리고머형 디올로 개질된 상온주형용 PU 엘라스토머의 반응과 물성)

  • Ahn, Won-Sool;Kim, Hoon-Seop
    • Elastomers and Composites
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    • v.43 no.1
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    • pp.18-24
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    • 2008
  • An oligomeric diol was utilized as a modifier for the reaction rate and mechanical properties of a RT-castable polyurethane elastomer. Both the reaction rate and the tensile strength of the blend samples, in which the modifier and the base resins were mixed with one-shot method, showed an exponential decrease as the increase of modifier concentration. Thermal analysis method of Kissinger was also effectively applied in the present study, showing good linearity in the plot of ln $(q/T^2_p)$ vs. $(1/T_p)$ and activation energy $E_a$ of 44.80 kJ/mol, which is similar to the general castable polyurethane. In the mechanical properties, remarkable decrease of strength was found by the addition of modifier concentration range up to about 20 phr, while characteristic elongation property of the elastomer, high elongation at lower strength, was observed over 20 phr of the modifier. Exponential decrease of the break strength of the blend sample exhibited that the mechanical properties of the blend might be considerably sensitive to the modifier concentration.

A Study of Crystallization and Fracture Toughness of Glass Ceramics in the $ZrO_2.SiO_2$ Systems Prepared by the Sol-Gel Method (졸-겔법으로 제조한 $ZrO_2.SiO_2$계 결정화유리의 결정화 및 파괴인성에 관한 연구)

  • 신대용;한상목;강위수
    • Journal of the Korean Ceramic Society
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    • v.37 no.1
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    • pp.50-56
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    • 2000
  • Precursor gels with the composition of xZrO2·(100-x)SiO2 systems (x=10, 20 and 30 mol%) were prepared by the sol-gel method. Kinetic parameters, such as activation energy, Avrami's exponent, n, and dimensionality crystal growth value, m, have been simultaneously calculated from the DTA data using Kissinger and Matusita equations. The crystallite size dependence of tetragonal to monoclinic transformation of ZrO2 was investigated using XRD, in relation to the fracture toughness. The crystallization of tetragonal ZrO2 occurred through 3-dimensional diffusiion controlled growth(n=m=2) and the activation energy for crystallization was calculated using Kissinger and Matusita equations, as about 310∼325±10kJ/mol. The growth of t-ZrO2, in proportion to the cube of radius, increased with increasing heating temperature and hteat-treatment time. It was suggested that the diffusion of Zr4+ ions by Ostwald ripening was rate-limiting process for thegrowth of t-ZrO2 crystallite size. The fracture toughness of xZrO2·(100-x)SiO2 systems glass ceramics increased with increasing crystallite size of t-ZrO2. The fracture toughness of 30ZrO2·70SiO2 system glass ceramics heated at 1,100℃ for 5h was 4.84 MPam1/2 at a critical crystaliite size of 40 nm.

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Effects of Nano-Sized Inorganic Fillers on Polymerization and Thermal Degradation of Polyurethane Composites (나노사이즈 무기분말이 폴리우레탄복합체의 중합 및 열분해반응에 미치는 영향)

  • Lee, Joon-Man;Ahn, Won-Sool
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.11 no.3
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    • pp.1027-1034
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    • 2010
  • Effects of inorganic nano-powders on the polymerization and thermal degradation kinetics as well as the mechanical properties of polyurethane nano-composites were studied by both the measurement of polymerization temperature as a function of time and non-isothermal thermogravimetric analysis (TGA) as well as the Instron test. As the results from polymerization studies, the reaction rates of MMT-filled PU composites were faster than those of Ce500-filled ones, and moreover, the activation energies using Kissinger method for the thermal degradation of composites were calculated as 139.34 kJ/mol for the Ce500-filled PU composites and 91.12 kJ/mol for MMT-filled one, respectivel, exhibiting that MMT nano-powder seemed to be acting as the catalyst for both polymerization and degradation of PU composites. UTM result, however, showed that tensile strength at break of MMT-filled composites was much higher than that of Ce500-filled ones above the concentrations range of 5 phr in the composites.

DGEBA-MDA-SN-Hydroxyl Group System and Composites -Cure Kinetics and Mechanism in DGEBA/MDA/SN/HQ System- (DGEBA-MDA-SN-Hydroxyl계 복합재료의 제조 -DGEBA-MDA-SN-HQ계의 경화반응 속도론 및 메카니즘-)

  • Shim, Mi-Ja;Kim, Sang-Wook
    • Applied Chemistry for Engineering
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    • v.5 no.3
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    • pp.517-523
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    • 1994
  • The effects of cure kinetics and mechanism of DGEBA(diglycidyl ether of bisphenol A)/MDA(4,4'-methylene dianiline) with SN(succinonitrile) and HQ(hydroquinone) as an additive and accelerator were investigated. Cure kinetics was evaluated by Kissinger equation and fractional-life method through DSC analysis. The activation energy has hydroxyl group as an accelerator, the activation energy and the starting cure-temperature were lower than those of DGEBA/MDA/SN system. Cure mechanism of those systems was investigated through FT-IR according to the various SN contents. The ratio was SN : HQ = 4 : 1. It has been known that the cure reactions of an epoxy-diamine system are composed of primary amine-epoxy reaction, secondary amino-epoxy reaction and epoxy-hydroxyl group reaction. But in DGEBA/MDA/SN system, primary amino-CN group reaction and CN group-hydroxyl group reaction were added to the above mentioned reactions. These reactions attributed to the long main chain and the low crossliking density. And in DGEBA/MDA/SN/HQ system, hydroxyl group of HQ formed a transition state with epoxide group and amime group and also opened the ring of the epoxide group rapidly, then amino-epoxy reaction took place easily.

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Thermal Characterization for HTPE IM Propellants (HTPE 둔감 추진제의 열특성)

  • Yoo, Ji-Chang;Kim, Jun-Hyung;Kim, Chang-Kee;Seo, Tae-Seok
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • pp.177-180
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    • 2009
  • This study was investigated to know the thermal decomposition for the propellant ingredients and 2 kinds of HTPE propellants. The thermal analysis of the propellant ingredients used in this study showed that the thermal stability of these materials decreases in the following order : AP > HTPE > AN > BuNENA. In addition, propellant HTPE 002 containing AN showed that an endothermic process at around $125^{\circ}C$ corresponding to the solid-solid phase change($II{\rightarrow}I$) of AN was followed by the exothermic process due to decomposition of BuNENA/AN until $200^{\circ}C$. The critical temperature, $T_c$, of thermal explosion for the propellants HTPE 001 and HTPE 002, were obtained from the non-isothermal curves at various heating rates, by using Semenov's thermal explosion theory. Kissinger's method was employed to obtain the activation energy of the thermal decomposition, and it was used to calculate the $T_c$.

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Study on Cure Behavior of Low Temperature and Fast Cure Epoxy with Mercaptan Hardener (Mercaptan 경화제에 의한 저온속경화 에폭시의 경화거동에 관한 연구)

  • Eom, Se Yeon;Seo, Sang Bum;Lee, Kee Yoon
    • Polymer(Korea)
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    • v.37 no.2
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    • pp.240-248
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    • 2013
  • The curing behaviors of diglycidyl ether of bisphenol A (DGEBA) with mercaptan hardener were studied by the comparison with amine-adduct type hardener. Curing behaviors were evaluated by DSC at dynamic and isothermal conditions. In the DSC, the dynamic experiments were based on the method of Kissinger's equation, and the isothermal experiments were fitted to the Kamal's kinetic model. Activation energy of epoxy/amine-adduct type hardener was ca. 40 kcal/mol. As the functional group of mercaptan hardener, -SH increased, on epoxy/mercaptan hardeners, the activation energies decreased from 28 to 19 kcal/mol. Epoxy/amine-adduct type hardener was initiated at $90^{\circ}C$ or higher. However, epoxy/mercaptan hardeners reduced the initiation temperatures below $80^{\circ}C$ and shortened the durations of curing reaction within 10 min. We found out that the reaction kinetics of epoxy with mercaptan hardener followed the autocatalytic reaction models, and the maximum reaction rates were shown at the conversions of 20~40%.

A Study on the Kinetics of Thermal Degradation of Polyethylene (폴리에틸렌 열분해의 속도론적 연구)

  • Kim, Myung Soo;Oh, Sea Cheon;Lee, Hae Pyeong;Kim, Hee Taik;Yoo, Kyong Ok
    • Applied Chemistry for Engineering
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    • v.10 no.4
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    • pp.548-556
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    • 1999
  • The thermal degradation of polyethylene has been studied using a nonisothermal thermogravimetric technique under a nitrogen atmosphere condition at several heating rates from 10 to $50^{\circ}C/min$. To obtain information on the kinetic parameters, the dynamic thermogravimetric analysis curve and its derivative have been analyzed by a variety of analytical methods such as Kissinger, Freeman-Carroll, Flynn-Wall, Coats-Redfern, Chatterjee-Conrad, Friedman, Horowitz-Metzger, Ozawa and Denq methods. The comparative works for the kinetic results obtained from various methods should be performed to determine the kinetic parameters, because three are tremendous differences in the calculated kinetic parameters depending upon the mathematical method taken in the analysis. From this work, it was found that the apparent activation energy of HDPE was larger than those of LDPE and LLDPE.

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Fabrication of Inorganic Filler-Polyurethane Composite Foam and Postcure Effect on Mechanical Properties (무기분말-폴리우레탄 복합체폼의 제조 및 후처리가 기계적 물성에 미치는 영향)

  • Ahn, Won-Sool;Lee, Boo-Youn
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.12 no.5
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    • pp.2451-2456
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    • 2011
  • Inorganic micropowder(Ce500)-filled polyurethane composite foams were fabricated and the effects of postcure on the mechanical properties were studied by the measurement of polymerization temperature, TGA, and UTM test. Temperature for the maximum reaction rate of 20wt% Ce500-filled sample reached upto ca. $100^{\circ}$ within 10min. and, for the same sample, double mode thermal decomposition was observed around two distinguished temperatures of $250^{\circ}$ and $350^{\circ}C$. The activation energies for the decomposition were calculated using Kissinger method as 117.4 and 139.4 kJ/mol, respectively. While break strength and hardness of the sample seemed nearly affected by postcure time at $160^{\circ}C$, elongation, however, was significantly changed upto 1.72 times after 7hrs treatment. As the results, the condition of 7hrs at $160^{\circ}$ was considered as the optimum postcure condition for the Ce500-filled PU composite foam samples.

Curing Behavior and Morphology of DGEBA/NMA/2,4,6-tris(dimethylaminomethyl) phenol System (DGEBA/NMA/2,4,6-tris(dimethylaminomehyl)phenol 시스템의 경화거동 및 Morphology)

  • 김민영;김성호;최영선;김원호;황병선
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.118-121
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    • 2001
  • The investigation of cure kinetics and morphology studies on DGEBA/PEI/Anhydride system were performed by differential scanning calorimetry and scanning electron microscopy. Autocatalystic kinetics model was applied by isothermal scan test. Ozawa method and Kissinger method was applied by temperature scan. Activation energy was 95kJ/mol for neat DGEBA/NMA, 120kJ/mol for DGEBA/PEI(10p.h.r.)/NMA. The generation of secondary phase of PEI was observed and its size was grown up by increasing contents of PEI.

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A Study on Annealing of Fe-Si-B-Ni Amorphous Alloy (Fe-Si-B-Ni 비정질 합금의 어닐링에 관한 연구)

  • Kim, Shin-Woo;Song, Yong-Sul;Baek, Mu-Hum
    • Korean Journal of Materials Research
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    • v.13 no.11
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    • pp.721-724
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    • 2003
  • A Fe-Si-B-Ni amorphous alloy manufactured by one roll melt-spinning method showed the crystallization temperature difference of a maximum $10^{\circ}C$ according to each lot. This temperature difference had a considerable influence on the annealing process to be conducted for obtaining the proper inductance of the alloy. The proper annealing temperature of the alloy was $480^{\circ}C$ and the annealing time increased as the crystallization temperature increased. The activation energy measured by Kissinger method increased as the crystallization temperature increased. Therefore, the annealing process must be adjusted by the crystallization temperature difference of the amorphous alloy.