• Title, Summary, Keyword: latent thermal initiator

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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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Cure Kinetics and Thermal Properties of Epoxy Resin Initiated by Methylanilinium Salts as a Latent Cationic Curing Agent (잠재성 양이온 경화제로서 methylanilinium 염에 의해 개시된 에폭시 수지의 경화 동력학 및 열적 특성)

  • 김택진;박수진;이재락
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.34-37
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    • 2000
  • The effect of novel N-crotyl-N,N-dimethyl-4-methylanilinium hexafluroantimonate (CMH) curing agent on cure behavior and thermal properties of DGEBA epoxy cationic system was investigated. From DSC measurements of DGEBA/CMH system, it was shown that this system exhibits an excellent thermal latent characteristic in a given temperature and reveals complex cure behavior as indicated by multiple exotherms. The conversion and conversion rate of DGEBA/CMH system increased with increasing the concentration of initiator due to high activity of CMH. Viscoelastic properties during gel formation of DGEBA with CMH were investigated by rheological techniques under isothermal condition. The gel time obtained from the modulus crossover. point t(G')=G", was affected by high curing temperature and concentration of CMH, resulting in high degree of network formation in cationic polymerization. The thermal stabilities were discussed in terms of the activation energy for decomposition and thermal factors determined from TGA measurements.ents.

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Cure Behaviors of Epoxy Resin Initiated by Methylanilinium Salts as Latent Cationic Curing Agent (잠재성 양이온 경화제인 Methylanilinium염에 의해 개시된 에폭시 수지의 경화 거동)

  • 박수진;김택진;이창진;이재락;박정규
    • Polymer Korea
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    • v.25 no.2
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    • pp.168-176
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    • 2001
  • The effect of novel N-crotyl-N,N-dimethyl-4-methylanilinium hexafluoroantimonate (CMH) curing agent as a thermal latent initiator on thermal behaviors, rheological properties, and thermal stability of diglycidylether of bisphenol A (DGEBA) epoxy cationic system was investigated. From DSC measurements of DGEBA/CMH system, it was shown that this system exhibits an excellent thermal latent characteristic at a given temperature. The conversion and conversion rate of DGEBA/CMH system increased with increasing the concentration of initiator, due to high activity of CMH. Rheological properties of the system were investigated under isothermal condition using a rheometer The gelation time was obtained from the analysis of storage modulus (G'), loss modulus (G"), and damping factor (tan $\delta$). As a result, the reduction of gelation time was affected by high curing temperature and concentration of CMH, resulting in high degree of network formation in cationic polymerization, due to difference of activity. The thermal stability of the cured epoxy resin was discussed in terms of the activation energy for decomposition and thermal factors determined from TGA measurements.ents.

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Studies on Cure Behaviors and Rheological and Mechanical Properties of Epoxy/Polyurethane Blend System initiated by Latent Thermal Catalyst (열잠재성 촉매에 의한 에폭시/폴리우레탄 블랜드계의 경화거동, 유변학적 및 기계적 물성에 관한 연구)

  • Gang, Jun-Gil;Gwon, Su-Han;Park, Su-Jin
    • Journal of the Korean Chemical Society
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    • v.46 no.3
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    • pp.233-240
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    • 2002
  • In this work, the cure kinetics and rheological and mechanical properties of diglycidylether of bispheonol A (DGEBA, EP)/polyurethane (PU) blends were investigated. The 1 wt% N-benzylpyrazinium hexafluoroantiminate (BPH) was used as a latent thermal catalyst. Latent properties were performed by measurement of the conversion as a function of reaction temperature using DSC. And the rheological properties of the blend systems were investigated under isothermal conditions using a rheometer. Crosslinking activating energies (Ec) were also determined from the Arrhenius equation based on gel time and curing temperature. The impact strengths were measured as mechanical properties of the casting specimens. The BPH in the blend systems could be an excellent latent thermal catalyst without any co-initiator. The rheological results showed that Ec was highest when PU content was 30 wt% which was in good agreement with the impact strengths. This was probably due to the intermolecular hydrogen bonding between the hydroxyl group in PU and EP, resulting in increasing the crosslinking density.

Thermally Induced Cationic Polymerization of Glycidyl Phenyl Ether Using Novel Xanthenyl Phosphonium Salts

  • Gupta, Mukesh Kumar;Singh, Raj Pal
    • Macromolecular research
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    • v.17 no.4
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    • pp.221-226
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    • 2009
  • The present study firstly describes the synthesis of novel, thermo-latent initiators based on xanthenyl phosphonium salts with different counter anions and phosphine moieties and secondly examines their efficiency in the bulk polymerization of glycidyl phenyl ether(GPE). The polymerization was performed with phosphonium salt initiators($I_{SbF6}$, $I_{PF6}$, $I_{AsF6}$ and $I_{BF4}$) at ambient temperature to $200^{\circ}C$ for 1 h. The order of initiator activity was $I_{SbF6}>I_{PF6}>I_{AsF6}>I_{BF4}$. To examine the effect of the phosphine moiety on the initiator activity, polymerization was carried out with $I_{SbF6}(Ph_{3}P)$ and $II_{SbF6}(Bu_{3}P)$ at ambient temperature to $170^{\circ}C$ for 1 h. The order of reactivity was $I_{SbF6}>II_{SbF6}$. In general, the conversion percentage increased with increasing polymerization temperature. The thermal stability of these salts was measured by thermo gravimetric analysis(TGA). The solubility of phosphonium salts in various organic solvents and epoxy monomers was also investigated.

Synthesis and Latent Characteristics of Thermal Cationic Latent Catalysts by Change of Substituent (치환기 변화에 따른 열잠재성 양이온 촉매의 합성과 잠재특성 연구)

  • Park, Soo-Jin;Heo, Gun-Young;Lee, Jae-Rock;Shim, Sang-Yeon;Suh, Dong-Hack
    • Polymer Korea
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    • v.25 no.4
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    • pp.558-567
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    • 2001
  • The syntheses of thermal latent catalysts have been carried out by modifying the substituent of pyrazinium salts. The thermal latent properties and cure behaviors of difunctional epoxy resin (diglycidylether of bisphenol-A, DGEBA) with 1 wt% of catalyst as an initiator were investigated by dynamic DSC method. As a result, the synthesized catalysts showed the good latent thermal properties in epoxy system. With increasing the basicity of substituted catalyst, the cure temperature and activation energy of epoxy system were increased, whereas the activity was decreased. This was probably due to the fact that the activity and cure behavior were controlled by ring strain and basicity of substituent. Consequently, the catalyst activity modified by methyl group as an electron donor was decreased in increasing of basicity in an initiation step of epoxy cure system. This is due to a decreasing of stabilities of both leaving group of pyrazinium salts and benzyl cation. However, the catalyst activity modified by cyano group as an electron acceptor was increased in increasing the stability of benzyl cation resulting from organic effects and resonance.

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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.

Rheological Properties and Cure Kinetics of Cycloaliphatic/DGEBA Epoxy Blend System Initiated by Cationic Latent Curing Agent (잠재성 경화제를 이용한 Cycloaliphatic/DGEBA계 에폭시 블렌드 시스템의 유변학적 특성 및 경화 동력학)

  • 곽근호;박수진;이재락;김영근
    • The Korean Journal of Rheology
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    • v.10 no.4
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    • pp.227-233
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    • 1998
  • The effects of 1 mol% N-benzylpyrazinium hexafluoroantimonate(BPH) as a thermal latent initiator and blend compositions composed of cycloaliphatic and DGEBA epoxies were investigated in the rheological properties and cure kinetics. Latent properties were performed by measurement of the conversion as a function of reaction time using isothermal DSC at $150^{\circ}C$ and $50^{\circ}C$ Rheological properties of the blend systems were investigated in terms of isothermal experiments using a rheometer. The gelation time was obtained from the evaluation of storage modulus (G'), loss modulus (G") and damping factor (tan$\delta$)). Cross-linking activation energy ($E_c$) was also determined from the Arrhenius equation based on gel time and curing temperature. As a result, the gel time and cross-linking activation energy increased with increasing DGEBA composition. The cure activation energies ($E_a$) were obtained by Kissinger method using dynamic DSC thermograms. In this work, the cure activation energy decreased with increasing CAE concentration, which might be resulted from the short repeat units, simple side-groups and viscosity of reaction media.edia.

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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.