• Title, Summary, Keyword: cure behaviors

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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.

Cure Behaviors and Mechanical Interfacial Properties of Epoxy/Polyurethane Blends (에폭시/우레탄 블렌드의 경화거동과 기계적 계면특성에 관한 연구)

  • Seok Su-Ja;Lee Jae-Rock;Park Soo-Jin
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.104-107
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    • 2004
  • In this work, the blend of diglycidylether of bisphenol A (DGEBA) and modified polyurethane (PU) was prepared and characterized in the cure behaviors and mechanical interfacial properties. The N-benzylpyrazinium hexafluoroantimonate was used as a cationic initiator for cure, and the content of PU was varied within 0-20 phr. The cure behaviors and mechanical interfacial properties were studied by DSC, near­IR, and the critical stress intensity actor $(K_{IC})$ measurements. Also thermal stabilities were carried out by TMA and TGA analyses. As a result, the cure activation energy $(E_a)$ and the conversion $(\alpha)$ were slightly increased with increasing the PU content, and a maximum value was found at 10 phr PU. The mechanical interfacial properties measured from $K_{IC}$ showed a similar behaviors with the results of conversion. These results were probably due to the increase of the hydrogen bonding between the hydroxyl groups of DGEBA and isocyanate groups in PU.

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Studies on Cure Behavior and Thermal Stability of Epoxy/PMR-15 Polyimide Blend System (에폭시/PMR-15 폴리이미드 블렌드계의 경화동력학 및 열안정성에 관한 연구)

  • Lee, Jae-Rock;Lee, Hwa-Young;Park, Soo-Jin
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.265-268
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    • 2002
  • In this work, the blend system of epoxy and PMR-15 polyimide is investigated in terms of the cure behaviors and thermal stabilities. The cure behaviors are studied in DSC measurements and thermal stabilities are also carried out by TGA analysis. DDM (4, 4'-diamino diphenyl methane) is used as curing agent for EP and the content of PMR-15 is varied within 0, 5, 10, 35, and 20 phr to neat EP. As a result, the cure activation energy ($E_a$) is increased at 10 phr of PMR-15, compared with that of neat EP. From the TGA results of EP/PMR-15 blend system, the thermal stabilities based in the initial decomposed temperature (IDT) and integral procedural decomposition temperature (IPDT) are increased with increasing the PMR-15 content. The fracture toughness, measured in the context of critical stress intensity factor ($K_{IC}$) and critical strain energy release rate ($G_{IC}$), shows a similar behavior with $E_a$. This result is probably due to the crosslinking developed by the interactions between intermolecules in the polymer chains.

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Cure Monitoring of Thick HSPE/Vinylester Composites with Dielectrometry (유전율 분석법에 의한 두꺼운 HSPE/Vinylester 복합재료의 경화 거동 관찰)

  • 이승구;김동철;주창환
    • Textile Science and Engineering
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    • v.38 no.5
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    • pp.214-221
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    • 2001
  • HSPE/vinylester 50-ply laminates, thicker than 1 inch, were fabricated by compression molding. To investigate the consolidation procedure of thick HSPE/vinylester composites, a dielectrometric(DEM) cure monitoring with dielectric sensors the thermocouples was utilized. Behaviors of the ion viscosity(a reciprocal of ion conductivity) as a dielectric parameter was monitored and evaluated with the resin viscosity. minimum viscosity temperature and cure temperature were analyzed from the dynamic cure experiments. To obtain the proper compaction of composites, step cure process including an intermediate dwell step at 8$0^{\circ}C$ was set-up to coincide the viscosity window between inner and outer layers of the composite. From the result of DEM analysis, the optimum cure cycle for a thick HSPE/vinylester composite in compression molding was established. In addition, the effects of molding pressure on the properties of composites were evaluated.

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Effects of Foaming Temperature and Carbon black Content on the Cure Behaviors and Foaming Characteristics of the Natural Rubber Foams (발포온도와 카본블랙 함량이 천연고무 발포체의 가황거동 및 발포특성에 미치는 영향)

  • Choi, Kyo-Chang;Kim, Joon-Hyung;Yoon, Jin-Min;Kim, Soo-Yeon
    • Elastomers and Composites
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    • v.41 no.3
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    • pp.147-156
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    • 2006
  • To investigate the influence of the foaming temperature and carbon black content on the cure behaviors and foaming characteristics of the foams. natural rubber (NR) was foamed at five temperature zones (145, 150, 155, 160 and $165^{\circ}C$) and different feeding ratios of the carbon black. A decreasing trend of the scorch time, $t_{s2}$ and cure time, $t_{90}$ was observed upon increasing foaming temperature and carbon black content. The optimal temperature for vulcanization and foaming of NRs in this study was considered to be $165^{\circ}C$ where density of the loomed NRs is lower than those at other four temperature regions. The rule rate index of the NRs foamed at $145^{\circ}C$ is smaller than those at 150, 155, 160 and $165^{\circ}C$. The results of the expansion ratio and micrographs of the foamed NRs were founded to support the density characteristics. The thickness of each of the struts formed inside the rubber matrix decreases with increasing the foaming temperature, while it increases with increasing the carbon black content.

Cure Kinetics for the Acid Anhydride-cured Epoxy System Using a Near-infrared Reflection Spectroscopy (근적외선 분광분석을 통한 산무수물경화 에폭시 시스템의 경화 동력학)

  • 곽근호;박수진;이재락
    • Polymer Korea
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    • v.24 no.1
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    • pp.65-71
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    • 2000
  • The latent properties and cure kinetics of an acid anhydride-cured epoxy resin have been investigated by a near-infrared (NIR) reflection spectroscopy. The assignments of the latent properties and cure behaviors were performed by the measurements of the NIR reflectance for epoxide and hydroxyl groups at different temperatures. A comprehensive analysis of the origin, location, and shifts during reaction of all major NIR absorption peaks in the spectral range from 4000 to 7100 $cm^{-1}$ / was provided. The extent of reaction was determined from NIR absorption band at the 4530 $cm^{-1}$ / depending on epoxide concentration and cure temperature.

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Influence of the Cure Systems on Long Time Thermal Aging Behaviors of NR Composites

  • Choi, Sung-Seen;Kim, Jong-Chul;Lee, Seung-Goo;Joo, Yong-L.
    • Macromolecular research
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    • v.16 no.6
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    • pp.561-566
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    • 2008
  • NR composites with different curing systems were aged thermally at 60, 70, 80, and $90^{\circ}C$ for 2-185 days in a convection oven, and the changes in the crosslink density were investigated as a function of the accelerated thermal aging. The overall crosslink densities increased with increasing aging time irrespective of the aging temperatures and curing systems. The changes in crosslink density were enhanced by increasing the aging temperature. The degree of the increased crosslink density was in the following order: "the conventional cure system > the semi-EV system > the EV system". For short term thermal aging, the change in crosslink density with the aging time was complicated, particularly for low temperature aging. The activation energies of the change in crosslink density with thermal aging using the conventional and semi-EV cure systems increased and then remained relatively constant with increasing aging time, whereas that of the specimen with an EV cure system tended to increase linearly. The experimental results were explained by the dissociation of the existing polysulfidic linkages and the formation of new cross links through the crosslinking-related chemicals remaining in the sample.

Cure Behaviors and Mechanical Interfacial Properties of Epoxy/Polyurethane Blends Initiated by Latent Thermal Catalyst (열잠재성 개시제에 의한 에폭시/폴리우레탄 블렌드의 경화거동 및 파괴인성)

  • Park, Soo-Jin;Seok, Su-Ja;Kang, Jun-Gil;Kwon, Soo-Han
    • Elastomers and Composites
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    • v.39 no.1
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    • pp.42-50
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    • 2004
  • In this work, the diglycidylether of bisphenol A (DGEBA) and modified polyurethane (PU) blends were initiated by N-benzylpyrazinium hexafluoroantimonate (BPH). The cure and fracture toughness of neat DGEBA with the addition of PU were investigated. The cure properties of DGEBA/PU blend system were examined by DSC and near-IR measurements. The fracture touhtness were investigated by measuring the critical stress intensity factor ($K_{IC}$) and the critical strain energy release rate ($G_{IC}$). According to the results, the maximum values of owe activation energy ($E_a$) and conversion (${\alpha}$) were found at 10 phr of PU. Also the $K_{IC}$ showed a similar behavior with the results of conversion. These results were probably due to increase of crosslinking density in the blends resulted from increase of the hydrogen bonding between the hydroxyl groups of DGEBA and isocyanate groups of PU.

Effects of Reactive Compatibilizers on the Morphology and Properties of Natural Rubber/SiO2 Composites

  • Lee, Min Young;Park, Jin Young;Song, Ki Chan;Kim, Su Kyung
    • Elastomers and Composites
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    • v.51 no.2
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    • pp.106-112
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    • 2016
  • Maleimidopropyltriethoxysilane grafted natural rubber (MISNR) was prepared by reaction of maleic anhydride grafted natural rubber and 3-aminopropyl triethoxysilane. MISNR was used as the compatibilizer of natural rubber/silica composites. The composites were prepared by two-step mixing procedures. The final mixtures were cured with optimum cure condition, which was established by a rheometer. Effects of the amounts of compatibilizer in the composites on the cure characteristics, morphology, thermal stability, and physical and mechanical behaviors were investigated. The composites having MISNR had shown cure characteristics and physical and mechanical properties superior to those without MISNR. Silica particles in the former appeared to be more uniform and reduced in size compared with the latter. The effects of the types of silica were also evaluated.