• Journal of the Semiconductor & Display Technology
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• v.13 no.4
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• pp.27-32
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• 2014

The cure properties of self-extinguishing epoxy resin systems with different charge transfer type latent catalysts were investigated, which are composed of YX4000H as a biphenyl epoxy resin, MEH-7800SS as a hardener, and charge transfer type latent catalysts. We designed and used five kinds of charge transfer type latent catalyst and compared to epoxy resin systems with Triphenylphosphine-Benzoquinone(TPP-BQ) as reference system. The cure kinetics of these systems were analyzed by differential scanning calorimetry with an isothermal approach, the kinetic parameters of all systems were reported in generalized kinetic equations with diffusion effects. The epoxy resin systems with Triphenylphosphine-Quinhydrone(TPP-QH), Triphenylphosphine-Benzanthrone(TPP-BT) and Triphenylphosphine-Anthrone(TPP-AT) as a charge transfer type latent catalyst showed a cure conversion rate of equal or higher rate than those with TPP-BQ. These systems with TPP-QH and Triphenylphosphine-Tetracyanoethylene(TPP-TCE) showed a critical cure reaction conversion of equal or higher conversion than those with TPP-BQ. The increases of cure conversion rates could be explained by the decrease of the activation energy of these epoxy resin systems. It can be considered that the increases of critical cure reaction conversion would be dependent on the crystallinity of the biphenyl epoxy resin systems.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.5
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• pp.84-90
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• 2020

The adhesion strength of two konds of solid propellants(primary propellant/secondary propellant) was studied by coating agent of adhesion composition composed of organic solvent, curing agent, and cure catalyst. The coating agent using FeAA, cure catalyst, resulted propellant breaking at more 0.14 wt% and interface breaking at less 0.10 wt%. The TPB cure catalyst of confirmed the result of the interface breaking immediately after curing of the secondary propellant. In addition, the coating agent using TPB was found to increase the adhesion strength between the primary propellant and the secondary propellant over time.

• Polymer(Korea)
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• v.33 no.4
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• pp.290-296
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• 2009

The morphology and mechanical properties of epoxy/polyamide/MPD/2E4MZ-CN reactive blends with various amount of catalyst were investigated. The cure behaviors, mechanical strengths, and morphological changes of the epoxy blend systems were analyzed by using DSC, UTM, and SEM, respectively. The amount of catalyst ranged from 0 to 3 phr, and the cure reaction occurred at $170^{\circ}C$ for 30 min. The maximum peaks in heat flow during cure reactions appeared at slightly lower temperature with increasing catalyst content, indicating that the cure reactions start at lower temperature by adding catalyst and polyamide rarely hinders the cure reaction paths. The co-continuous morphology was found in epoxy/polyamide(20 phr) blends and by adding catalyst to the blends much clearer and uniform co-continuous phase was observed. The surface tension of the mechanical test specimen was increased due to the AP plasma surface treatment, and then adhesion strength was increased by over 20% by adding 2 phr of catalyst to the blends. When considering morphological tuning of the blends by means of catalyst incorporation, it is expected that the increased elongation and adhesion strength can be achieved in the structural adhesive systems.

• Macromolecular Research
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• v.10 no.1
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• pp.34-39
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• 2002

Cure behavior of an epoxy resin was investigated at different cure temperatures (110, 120, 130, 140, and 150 $^{\circ}C$) and cure times in the presence of 2 wt% of an N-benzylpyrazinium hexafluoroantimonate (BPH) cationic catalyst by means of differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The glass transition temperature ( $T_{g}$) and chemical conversion (x) at the different temperatures were determined from DSC thermograms. The $T_{g}$ and x vs. In time data were superposed up to $T_{g}$ = 10$0^{\circ}C$ and x = 0.70 by shifting horizontally at a reference temperature of $T_{g}$ = 13$0^{\circ}C$. It is interesting that the $T_{g}$ and x of the superposed data increase rather slowly in the early stage of cure and rapidly thereafter. Therefore, the increase of the $T_{g}$ and x can be divided into two regions; $R_{I}$= -18.4(= $T_{go}$ ) ~5$^{\circ}C$ and $R_{II}$ = 5 ~ 10$0^{\circ}C$ in $T_{g}$, and $R_{I}$ : 0~0.24 and $R_{II}$ : 0.24~0.70 in x. The $R_{I}$ is closely related to the initiation reactions between BPH and epoxy and between hydroxy group and epoxy in this epoxy/catalyst system. From the kinetic analysis of the $T_{g}$-shift, activation energy was 12.5 kcal/mol. The relationship between $T_{g}$ and x was also considered. The gelation and vitrification times for different cure temperatures were obtained from DMA curves.urves. DMA curves.urves.

• Journal of the Semiconductor & Display Technology
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• v.19 no.1
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• pp.29-35
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• 2020

The cure characteristics of three kinds of naphthalene type epoxy resins(NET-OH, NET-MA, NET-Epoxy) with a 2-methyl imidazole(2MI) catalyst were investigated for preparing sheet epoxy molding compound(SEMC) for wafer level package(WLP) applications, comparing with diglycidyl ether of bisphenol-A(DGEBA) and 1,6-naphthalenediol diglycidyl ether(NE-16) epoxy resin. The cure kinetics of these systems were analyzed by differential scanning calorimetry with an isothermal approach, and the kinetic parameters of all systems were reported in generalized kinetic equations with diffusion effects. The NET-OH epoxy resin represented an n-th order cure mechanism as like NE-16 and DGEBA epoxy resins, however, the NET-MA and NET-Epoxy resins showed an autocatalytic cure mechanism. The NET-OH and NET-Epoxy resins showed higher cure conversion rates than DGEBA and NE-16 epoxy resins, however, the lowest cure conversion rates can be seen in the NET-MA epoxy resin. Although the NETEpoxy and NET-MA epoxy resins represented higher cure reaction conversions comparing with DGEBA and NE-16 resins, the NET-OH showed the lowest cure reaction conversions. It can be figured out by kinetic parameter analysis that the lowest cure conversion rates of the NET-MA epoxy resin are caused by lower collision frequency factor, and the lowest cure reaction conversions of the NET-OH are due to the earlier network structures formation according to lowest critical cure conversion.

• Restorative Dentistry and Endodontics
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• v.17 no.1
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• pp.36-54
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• 1992

The purpose of this study was to compare the shear bond strengths to ground dentin surfaces of four dentinal bonding agents in 193 teeth. Various dentin surfaces treated with four dentin bonding agents were attached with two restorative composite resins. The effectiveness of the bonding were tested by the monitoring the shear bond strength. The shear bond strengths were measured after 2 hours and 24 hours after surface conditioning with four dentin bonding agents. Effects of EDTA, the additive illumination, and sealer treatments without primer on bond strength to dentin surfaces were assessed. In addition the effects of the thickness of specimens ranging from 0.65 mm to 1.95 mm and the ratio of catalyst and base paste on the bond strength of chemical cure composite resin were estimated. The shear bond strength was determined by testing specimens in the Instron universal testing machine (Model No. 1122) at a crosshead speed of 1.0 mm/min. Following condusions were drawn: 1. The highest mean shear bond strengths of chemical cure composite resin to dentin conditioning with dentin bonding agents aged 2 hours were obtained, and then that was decreased with time followed by EDTA treatment. 2. In light cure composite resin, the shear bond strength was increased following dentin conditioning with bonding agents with time, irradiation time and EDTA treatment except in SB group. 3. The thicker the composite resin specimen was, the less the shear bond strength in chemical cure composite resin was. 4. In light cure composite resin, there was a little change in shear bond strength following dentin conditioning with bonding agents. 5. In chemical cure composite resin, the shear bond strength was the highest in the ratio of 1/1 of catalyst and base part. 6. Without a dentin primer, shear bond strength to dentin conditioned only with UB sealer was the highest among four sealers in light cure composite resin.

• Journal of the Korean Applied Science and Technology
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• v.24 no.4
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• pp.339-346
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• 2007

The influence of adding urea to phenol-formaldehyde (PF) resins as a co-polymer component were investigated aiming at synthesizing useful phenol-urea-formaldehyde resins. Urea was added at 10% by total resin weight. Several methods for the addition of urea to the PF resins during synthesizing resins to see the co-polymerization occurs between urea and PF resins. The urea was added at the beginning, at three different middle stages, and at the end of PF resin synthesis. The copolymerized methylene bridges between phenol and urea molecules were not observed by $^{13}C-NMR;$ no signal around 50ppm. The curing of urea-modified PF resins, evaluated by dynamic mechanical analysis(DMA), showed some differences among the resins. DMA gel times ranged from 2.75 min to 3.25 min and the resins made with earlier urea additions showed slightly shorter gel times. The longest cure time and gelation time was observed for the resin PFU. Catalyst effects on the DMA cure time values of resins were not significant with different amounts of catalyst or different types of catalyst for all resins tested. Gel times of urea-modified PF resins shortened the most by triacetin catalyst.

• Proceedings of the Korean Fiber Society Conference
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• 1999.10a
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• pp.9-12
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• 1999

• Applied Chemistry for Engineering
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• v.24 no.3
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• pp.320-326
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• 2013

In this study, various polyimide films were synthesized via low temperature cure in order to understand changes in their physical properties when using 4,4'-oxydianiline (ODA) as a diamine and dianhydride molecules with different backbones on a single diamine such as 4,4'-Oxydiphthalic anhydride (ODPA), 4,4-hexafluoroisopropylidene diphthalic dianhydride (6FDA), and 3,3', 4,4'-benzophenone tetracarboxylic dianhydride (BTDA). After the synthesis of poly(amic acid), polyimide films were fabricated by adding 1,4-diazabicyclo [2.2.2]octane (DABCO), a low-temperature catalyst, at various wt% to poly(amic acid)s. Changes of optical and thermal properties were compared and analyzed between polyimide films without catalyst and polyimide films with catalyst by FT-IR, UV-Vis transmittance, DSC/TGA, and WAXD analysis. Wide-angle X-ray diffraction (WAXD) analysis revealed that the mean intermolecular distance decreased with the use of a catalyst by the type of dianhydride. Thus, while the optical properties of the films improve by a low-temperature cure performed using a catalyst, their thermal properties decrease. These changes can be explained by the changes in the morphological structure of the films triggered by a catalyst-induced reduction in the mean intermolecular distance. Moreover, the results show that the type of dianhydride determines the degree of change in the optical and thermal properties in each types of polyimide, demonstrating that changes in the optical and thermal properties are directly associated with the backbone of the polyimide structure.

• 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.