• Title, Summary, Keyword: cure kinetics

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Cure Kinetics of a Bisphenol-A Type Vinyl-Ester Resin Using Non-Isothermal DSC

  • Ahn, WonSool
    • Elastomers and Composites
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    • v.53 no.1
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    • pp.1-5
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    • 2018
  • In the current research, the curing kinetics of a mixture system consisting of a Bisphenol-A type vinyl ester resin and styrene monomer was studied. Methylethylketone peroxide and cobalt octoate were used as the polymerization initiator and accelerator respectively. Thermograms with several different heating rates were obtained using non-isothermal differential scanning calorimetry. Activation energy values analyzed by the Flynn-Wall-Ozawa isoconversional method showed a three-step change with conversion ${\alpha}$: a slight decrease initially for ${\alpha}$ < 0.1, a constant value of 47.9 kJ/mol in the range 0.1 < ${\alpha}$ < 0.7, and a slow increase for 0.7 < ${\alpha}$. When assuming a constant activation energy of 47.9 kJ/mol, an autocatalytic model of the Sestak-Berggren equation was considered as the proper mathematical model of the conversion function, indicating an overall order of 1.2.

Cure Kinetics and Mechanical Interfacial Characteristics of Zeolite/DGEBA Composites (제올라이트/DGEBA 복합재료의 경화 동력학과 기계적 계면특성)

  • Soo-Jin Park;Young-Mi Kim;Jae-Sup Shin
    • Journal of the Korean Chemical Society
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    • v.47 no.5
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    • pp.472-478
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    • 2003
  • In this work, the zeolite/diglycidylether of bisphenol A(DGEBA) systems were investigated in terms of the cure kinetics and mechanical interfacial properties of the composites. The 4, 4-diamino diphenyl methane(DDM) was used as a curing agent for epoxy. Two types of zeolite(PZ) were prepared with 15 and 35 wt% KOH treatments(15-BZ and 35-BZ, respectively) for 24 h, and their surface characteristics were studied by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction(XRD). Cure kinetics of the composites were examined in the context of differential scanning calorimetry(DSC), and mechanical interfacial properties were investigated in critical stress intensity factor($K_{IC}$) and critical strain energy release rate($G_{IC}$). In the results of XPS and XRD, sodium ion(Na) of zeolite was exchanged for potassium ion(K), resulting from the treatment of KOH. Also, $Si_{2p}/Al{2p}$ composition ratios of the treated zeolite were increased, which could be attributed to the weakening of Al-O bond in framework. Cure activation energy($E_a$) of 15-BZ composites was decreased, whereas KIC and $G_{IC}$ were increased, compared with those of the pure zeolite/DGEBA composites. It was probably accounted that the acidity of zeolite was increased by surface treatments and the cure reaction between zeolite and epoxy was influenced on the increased acidity of zeolite.

Characteristics of Medical Polymer Based on Epoxy Resin System -Cure Characteristics for DGEBA/MDA/PGE- DMU System by Kissinger and Ozawa Equations- (에폭시 수지계 의료용 고분자 재료의 특성 연구 - Kissinger 식과 Ozawa 식에 의한 DGEBA/MDA/PGE-DMU 계의 경화특성 -)

  • Kim, Jang-Hoon;Lee, Jae-Young;Kim, Sang-Wook;Sim, Mi-Ja
    • Korean Journal of Materials Research
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    • v.11 no.9
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    • pp.727-732
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    • 2001
  • The cure kinetics of diglycidyl ether of bisphenol A (DGEBA)/4,4'- methylene dianiline (MDA) system with synthesized phenyl glycidyl ether-dimethylurea (PGE-DMU) was studied by Kissinger and Ozawa equations with DSC analysis in the temperature range of $20~300^{\circ}C$ To investigate the reaction mechanism between epoxy group of PGE and urea group of DMU, FT-lR spectroscopy analysis was used. The epoxide group of PGE reacted with the urea group of DMU and formed a hydroxyl group which acted as a catalyst on the cure reaction of other epoxide and amine groups. The activation energy of DGEBA/MDA system without PGE-DMU was 46.5 kJ/mol and those of the system with 5 and 10 phr of PGE- DMU were 43.4 and 37.0 kJ/mol, respectively. Ozawa method also showed the same tendency.

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Cure Kinetics of DGEBA/MDA/SN/HQ Thermosetting Matrix (열경화성 DGEBA/MDA/SN/HQ 매트릭스의 경화반응 속도)

  • Lee, Jae-Yeong;Sim, Mi-Ja;Kim, Sang-Uk
    • Korean Journal of Materials Research
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    • v.5 no.6
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    • pp.667-672
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    • 1995
  • Cure kinetics of DGEBA(diglycidyl ether of bisphenol A)/MDA(4, 4'-methylene dianiline)/SN(succinonitrile) system and DGEBA/MDA/SN/HQ(hydroquinone) system was studied by Kissinger equation and Fractional life method through DSC in the temperature range of 85∼150$^{\circ}C$. As cure temperature was increased, reaction rate increased and reaction order was almost constant. The reaction rate of the system with HQ as a catalyst was more higher and activation energy of that was lower about 20% than those of the system without HQ. Starting temperature of cure reaction for DGEBA/MDA/SN/HQ system decreased about 30$^{\circ}C$ than that of DGEBA/MDA/SN system.

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Studies on Cure Kinetics and Rheological Properties of Difunctional Epoxy/Polysulfone Blend System (이관능성 에폭시/폴리썰폰 블렌드의 경화 동력학 및 유변학적 특성에 관한 연구)

  • 박수진;김현철;이재락
    • Polymer Korea
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    • v.25 no.2
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    • pp.177-185
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    • 2001
  • In this work, the cure kinetics and rheological properties of difunctional epoxy(diglycidylether of bisphenol A, DGEBA)/polysulfone (PSF) blends were investigated using differential scanning calorimeter and rheometer. From the DSC results of the blends, the temperature of the exothermic peak and cure activation energy (E) using a half-width method were increased with increasing the PSF content to neat epoxy resin up to 30 wt%. However, a marginal decrease in the blend system was shown in E. The conversion ($\alpha$) and conversion rate (d$\alpha$/dt) were decreased as the content of PSF increases. Rheological properties of the blend system were investigated under isothermal condition using a rheometer. Cross-linking activation energy (E$_{c}$) was determined from the Arrhenius equation based on gel time and curing temperature. As a result, the E$_{c}$ showed a similar behavior with E which could be resulted from high viscosity of PSF and the phase separation between DGEBA and PSF.PSF.f PSF and the phase separation between DGEBA and PSF.PSF.

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Cure Kinetics, Thermal Stabilities and Rheological Properties of Epoxy/phenol Resin Blend System Initiated by Cationic Thermal Latent Catalyst (양이온 열잠재성 개시제에 의한 에폭시/페놀 수지 브랜드 시스템의 경화 동력학.열안정성 및 유변학적 특성)

  • 박수진;서민강;이재락
    • The Korean Journal of Rheology
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    • v.11 no.2
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    • pp.135-142
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    • 1999
  • The effects of 1 wt.% N-benzylpyrazinium hexafluoroantimonate (BPH) as a thermal latent initiator and blend compositions composed of 0, 5, 10, 20 and 40 wt.% of phenol-novolac resin to epoxy resin were investigated in terms of cure kinetics, thermal stabilities and rheological properties. Thermal latent properties of BPH were measured from the conversion as a function of reaction temperature on a dynamic DSC. This cationic BPH system turned out to be an effective thermal latent initiator in the epoxy-phenol curing system. And the increase of phenol-novolac resin concentration led to the decrease in the latent temperature and to the increase of cure activation energy ($E_a$) of the blend system. The thermal stability and activation energy ($E_t$) for decomposition, gel-time and activation energy ($E_c$) for cross-linking from rheometer increased within the composition range of 20~40 wt.% of phenol-novolac resin. This implies that the three-dimensional cross-linking may take place among hydroxyl group within phenol resin, epoxide ring within epoxy resin and BPH.

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Non-isothermal TGA Study on Thermal Degradation Kinetics of ACM Rubber Composites (비등온 TGA를 이용한 ACM 고무복합재료의 열분해 거동 연구)

  • Ahn, WonSool;Lee, Hyung Seok
    • Elastomers and Composites
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    • v.48 no.2
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    • pp.161-166
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    • 2013
  • Thermal degradation behavior of chlorine cure-site ACM and carboxylic cure-site ACM rubbers was studied by non-isothermal TGA thermal analysis. Carboxylic cure-site ACM rubber exhibited comparatively more thermally stable than chlorine cure-site ACM, showing higher peak temperature, at which maximum reaction rate occurred. Activation energies from Kissinger method were calculated as 118.6 kJ/mol for the chlorine cure-site ACM and 105.5 kJ/mol for the carboxylic cure-site ACM, showing similar values from Flynn-Wall-Ozawa analysis over the conversion range of 0.1~0.2. From the analysis of the reaction order change, both samples seemed thermally decomposed through the multiple reaction mechanism as is the common rubber materials.

Studies on Cure Behaviors, Dielectric Characteristics and Mechanical Properties of DGEBA/Poly(ethylene terephthalate) Blends

  • Park, Soo-Jin
    • Macromolecular research
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    • v.17 no.8
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    • pp.585-590
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    • 2009
  • The cure behaviors, dielectric characteristics and fracture toughness of diglycidylether of bisphenol-A (DGEBA)/poly(ethylene terephthalate) (PET) blend system were investigated. The degree of conversion for the DGEBA/PET blend system was measured using Fourier transform infrared (FTIR) spectroscopy. The cure kinetics were investigated by measuring the cure activation energies ($E_a$) with dynamic differential scanning calorimetry (DSC). The dielectric characteristic was examined by dielectric analysis (DEA). The mechanical properties were investigated by measuring the critical stress intensity factor ($K_{IC}$), critical strain energy release rate ($G_{IC}$), and impact strength test. As a result, DGEBAIPET was successfully blended. The Ea of the blend system was increased with increasing PET content to a maximum at 10 phr PET. The dielectric constant was decreased with increasing PET content. The mechanical properties of the blend system were also superior to those of the neat DGEBA. These results were attributed to the increased cross-linking density of the blend system, resulting from the interaction between the epoxy group of DGEBA and the carboxyl group of PET.

Finite Element Analysis of Residual Stress Evolution during Cure Process of Silicone Resin for High-power LED Encapsulant (고출력 LED 인캡슐런트용 실리콘 레진의 경화공정중 잔류응력 발달에 대한 유한요소해석)

  • Song, Min-Jae;Kim, Heung-Kyu;Kang, Jeong-Jin;Kim, Kwon-Hee
    • Journal of the Korean Society for Precision Engineering
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    • v.28 no.2
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    • pp.219-225
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    • 2011
  • Silicone resin is recently used as encapsulant for high-power LED module due to its excellent thermal and optical properties. In the present investigation, finite element analysis of cure process was attempted to examine residual stress evolution behavior during silicone resin cure process which is composed of chemical curing and post-cooling. To model chemical curing of silicone, a cure kinetics equation was evaluated based on the measurement by differential scanning calorimeter. The evolutions of elastic modulus and chemical shrinkage during cure process were assumed as a function of the degree of cure to examine their effect on residual stress evolution. Finite element predictions showed how residual stress in cured silicone resin can be affected by elastic modulus and chemical shrinkage behavior. Finite element analysis is supposed to be utilized to select appropriate silicone resin or to design optimum cure process which brings about a minimum residual stress in encapsulant silicone resin.