• Title, Summary, Keyword: cure kinetics

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Cure Reactions of Epoxy/Anhydride/(Polyamide Copolymer) Blends

  • Youngson Choe;Kim, Wonho
    • Macromolecular research
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    • v.10 no.5
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    • pp.259-265
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    • 2002
  • The cure kinetics of blends of epoxy (DGEBA, diglycidyl ether of bisphenol A)/anhydride resin with polyamide copolymer, poly(dimmer acid-co-alkyl polyamine), were studied using differential scanning calorimetry (DSC) under isothermal condition. On increasing the amount of polyamide copolymer in the blends, the reaction rate was increased and the final cure conversion was decreased. Lower values of final cure conversions in the epoxy/(polyamide copolymer) blends indicate that polyamide hinders the cure reaction between the epoxy and the curing agent. The value of the reaction order, m, for the initial autocatalytic reaction was not affected by blending polyamide copolymer with epoxy resin, and the value was approximately 1.3, whereas the reaction order, n, for the general n-th order of reaction was increased by increasing the amount of polyamide copolymer in the blends, and the value increased from 1.6 to 4.0. A diffusion-controlled reaction was observed as the cure conversion increased and the rate equation was successfully analyzed by incorporating the diffusion control term for the epoxy/anhydride/(polyamide copolymer) blends. Complete miscibility was observed in the uncured blends of epoxy/(polyamide copolymer) up to 120 $^{\circ}C$, but phase separations occurred in the early stages of the curing process at higher temperatures than 120 "C. During the curing process, the cure reaction involving the functional group in polyamide copolymer was detected on a DSC thermogram.gram.

Study of Cure Kinetics of Vacuum Bag Only Prepreg Using Differential Scanning Calorimetry (시차주사열량계를 이용한 진공백 성형 프리프레그의 경화 거동 연구)

  • Hyun, Dong Keun;Lee, Byoung Eon;Shin, Do Hoon;Kim, Ji Hoon
    • Composites Research
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    • v.33 no.2
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    • pp.44-49
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    • 2020
  • The cure kinetics of carbon fiber-reinforced prepreg for Vacuum Bag Only(VBO) process was studied by differential scanning calorimetry (DSC). The total heat of reaction (ΔHtotal = 537.1 J/g) was defined by the dynamic scanning test using prepregs and isothermal scanning tests were performed at 130℃~180℃. The test results of isothermal scanning were observed that the heat of reaction was increased as the temperature elevated. The Kratz model was applied to analyze the cure kinetics of resin based on the test results. To verify the simulation model, the degree of cure from panels using different cure cycles were compared with the measurement. The simulation model showed that the error against the experimental value was less than 3.4%.

Effects of Carbon Black Content and Vulcanization Type on Cure Characteristics and Dynamic Mechanical Property of Styrene-Butadiene Rubber Compound

  • Changwoon Nah;Kim, Wan-Doo;Lee, Seag
    • Macromolecular research
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    • v.9 no.3
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    • pp.157-163
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    • 2001
  • The influences of carbon black loading and cure type on the cure characteristics including kinetics and dynamic mechanical properties were investigated for a styrene-butadiene rubber (SBR). The rate constants of accelerated sulfur vulcanization reaction at three different temperatures were determined using a cure rheometer, and they were compared with those from the direct measurement of sulfur concentration. The strain softening behavior under dynamic deformation, known as the Payne effect was also discussed depending on the carbon black loading and cure type.

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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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Autocatalytic Cure Kinetics of DGEBA/MDA/PGE-AcAm System (DGEBA/MDA/PGE-AcAm계의 자촉매 반응 속도론)

  • Lee, Jae-Yeong;Sim, Mi-Ja;Kim, Sang-Uk
    • Korean Journal of Materials Research
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    • v.8 no.9
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    • pp.797-801
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    • 1998
  • The cure kinetics for diglycidyl ether of bisphenol A(DGEBA)/4, 4'-methylene dianiline(MDA) system with or without lOphr of phenyl glycidyl ether(PGE)-acetamide(AcAm) was studied by autocatalytic cure expression. On the dynamic DSC curves, the exothermic peak temperature and the onset temperature of reaction decreased with the addition of PGE-AcAm. Regardless of the addition of PGE-AcAm, the shape of the conversion curve showed sigmoid, and this meant that DGEBA/MDA and DGEBA/MDA/PGE-AcAm systems followed autocatalytic cure reaction. When PGE-AcAm was added to DGEBA/MDA system, the cure rate increased about 1.2~1.4 times due to the catalytic role of hydroxyl groups in PGE-AcAm.

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Isothermal Cure Kinetics of Epoxy/Phenol-novolac/Latent Catalyst System (등온 DSC 열분석에 의한 Epoxy/Phenol-novolac/Latent Catalyst 조성물의 경화 동력학)

  • 박수진;서민강;이재락;이덕래
    • Textile Science and Engineering
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    • v.36 no.10
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    • pp.715-724
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    • 1999
  • The effects of different phenol-novolac resin contents and curing temperatures on isothermal cure kinetics of epoxy (diglycidyl ether of bisphenol-A)/ phenol-novolac/BPH (N-benzylpyrazinium hexafluoroantimonate) blend system were studied on a differential scanning calorimeter (DSC). Latent properties of blend system initiated by BPH, a cationic initiator, were analyzed at different temperatures by measuring the conversion as a function of curing time in isothermal DSC analysis. The BPH in this blend system appears to act as a thermally latent initiator. The isothermal cure kinetics of blend system using BPH suggest an autocatalytic kinetic mechanism, but vitrification occurs at higher conversions and curing becomes diffusion controlled. The kinetic rate constants, $k_1\;and\;k_2$ of blend system increased with increasing content of phenol-novolac resin at a fixed curing temperature, but the reaction order, m and n were independent of the phenol-novolac resin content and the curing temperature. The activation energies, $E_{a,1}$ and $E_{a,2}$ obtained from Arrhenius plot decreased with phenol-novolac resin content in the 20~40wt% range.

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A numerical study on the residual stress in LED encapsulment silicone considering cure process (경화공정을 고려한 LED 패키징 실리콘의 잔류음력에 대한 수치해석적 고찰)

  • Song, M.J.;Kim, K.B.;Kang, J.J.;Kim, H.K.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.323-327
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    • 2009
  • Silicone is recently used for LED chip encapsulment due to its good thermal stability and optical transmittance. In order to predict residual stress which causes optical briefringence and mechanical warpage of silicone, finite element analysis was conducted for both curing and cooling process during silicone molding. For analysis of curing process, a cure kinetics model was derived based on the differential scanning calorimetry(DSC) test and applied to the material properties for finite element analysis. Finite element simulation result showed that the curing as well as the cooling process should be designed carefully so as to reduce the residual stress although the cooling process plays the bigger role than curing process in determining the final residual stress state.

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Studies on Cure kinetics and Rheological Properties of Epoxy/Polyurethane Blend System (에폭시/폴리우레탄 블렌드계의 강화 동력학 및 유변학적 특성에 관한 연구)

  • 박수진;진중성;박병기
    • Textile Science and Engineering
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    • v.37 no.8
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    • pp.448-454
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    • 2000
  • The effects of composition ratios of epoxy resin (EP) and polyurethane (PU) blends on cure kinetics and reheological properties were investigated. In this work, 20 phr of DDM (4,4'- diamino diphenyl methane) was used as a curing agent for epoxy resin. And the composition of EP/PU was varied within 100/0∼100/40 phr. The cure activation energies ($E_{a}$), which were obtained from dynamic DSC data by Kissinger method, were increased in 40 phr of PU in EP than in pure EP. The rheological properties of blend system were investigated under isothermal condition using a rheometer. Crosslinking activation energies ($E_{c}$) were also determined from the Arrhenius equation based on gel time and curing temperature. As a result, both gelaton time and crosslinking activation energy increased with increasling the content of PU. These results could be explained by the increase in reactivity between the hydroxyl group in EP and isocyanate group in PU, resulting in an increase in the crosslinking density.

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A Kinetic Study of Biphenyl Type Epoxy-Xylok Resin System with Different Kinds of Catalysts

  • 한승;김환근;윤호규;문탁진
    • Bulletin of the Korean Chemical Society
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    • v.18 no.11
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    • pp.1199-1203
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    • 1997
  • The investigation of cure kinetics of biphenyl epoxy (4,4-diglycidyloxy-3,3,5,5-tetramethyl biphenyl)-xylok resin system with four different catalysts was performed by differential scanning calorimeter using an isothermal approach. All kinetic parameters of the curing reaction including the reaction order, activation energy and rate constant were calculated and reported. The results indicate that the curing reaction of the formulations using triphenylphosphine (TPP) and 1-benzyl-2-methylimidazole (1B2MI) as a catalyst proceeds through a first order kinetic mechanism, whereas that of the formulations using diazabicyloundecene (DBU) and tetraphenyl phosphonium tetraphenyl borate (TPP-TPB) proceeds by an autocatalytic kinetic mechanism. To describe the cure reaction in the latter stage, we have used the semiempirical relationship proposed by Chern and Poehlein. By combining an nth order kinetic model or an autocatalytic model with a diffusion factor, it is possible to predict the cure kinetics of each catalytic system over the whole range of conversion.

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Cure and Thermal Degradation Kinetics of Epoxy/Organoclay Nanocomposite

  • Park, Jae-Jun
    • Transactions on Electrical and Electronic Materials
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    • v.13 no.4
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    • pp.204-207
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    • 2012
  • Epoxy nanocomposite was synthesized through the exfoliation of organoclay in an epoxy matrix, which was composed of diglycidyl ether of bisphenol A (DGEBA), 4,4'-methylene dianiline (MDA) and malononitrile (MN). Organoclay was prepared by treating the montmorillonite with octadecyl trimethyl ammonium bromide (ODTMA). The exfoliation of the organoclay was estimated by wide angle X-ray diffraction (WAXD) analysis. In order to measure the cure rate of DGEBA/MDA (30 phr)/MN (5 phr)/organoclay (3 phr), differential scanning calorimetry (DSC) analysis was performed at various heating rates, and the data were interpreted by Kissinger equation. Thermal degradation kinetics of the epoxy nanocomposite were studied by thermogravimetric analysis (TGA), and the data were introduced to the Ozawa equation. The activation energy for cure reaction was 45.8 kJ/mol, and the activation energy for thermal degradation was 143 kJ/mol.