• Polymer(Korea)
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• v.27 no.3
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• pp.189-194
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• 2003

Interfacial evaluation, damage sensing and cure monitoring of single carbon fiber/thermo setting composite with different curing processes were investigated using electro-micromechanical test. After curing, the residual stress was monitored by measurement of electrical resistance and then compared to various curing processes. In thermal curing case, matrix tensile strength, modulus and interfacial shear strength were higher than those of ultraviolet curing case. The shrinkage measured during thermal curing occurred significantly by matrix shrinkage and residual stress due to the difference in thermal expansion coefficient. The apparent modulus measured in the thermal curing indicated that mechanical and interfacial properties were highly improved. The reaching time to the same stress of thermal curing was faster than that of UV curing case.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.13-13
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• 2004

나노테크놀러지 중의 한 가지인 나노임프린트 리소그래피 기술은 수 ∼ 수십 나노 급의 선폭을 가지는 스탬프(stamp)를 전자빔 리소그래피(electron beam lithography)를 이용하여 제작한 후 스탬프에 형성된 패턴과 동일한 형상을 원하는 곳에 모사하는 기술이다. 이 기술은 크게 열을 가하는 방식과 UV 경화성 수지를 이용한 방식으로 나뉜다. 열을 가하는 나노임프린트 리소그래피 방식의 경우는 열 경화성 수지를 이용하여 고온 조건에서 스탬프를 고압으로 눌러 원래의 형상을 모사하며, UV 나노임프린트는 광경화 반응을 이용하여 수지를 경화 시켜 모사하는 차이점이 있다.(중략)

• Polymer(Korea)
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• v.26 no.1
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• pp.80-87
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• 2002

A comparative study using electron-beam(EB) and thermal curing techniques was carried out to determine the effect of cure behavior and thermal stability of epoxy resins. In this work, benzylquinoxalinium hexafluoroantimonate(BQH) was used as a latent cationic catalyst for an epoxy resin. According to the thermogravimetric analysis(TGA), the decomposed activation energy based on Coats-Redfern method was higher in the case of thermal curing technique. This could be interpreted in terms of slow thermal diffusion rate resulted from high crosslink density of the thermally cured epoxy resin. However, the increase of hydroxyl group in the epoxy resin cured by EB technique was observed in near-infrared spectroscopy(NIRS) measurements, resulting in improving the stable short aromatic chain structure, integral procedural decomposition temperature, and finally ductile properties for high impact strengths.

• Proceedings of the Korean Society For Composite Materials Conference
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• 1999.04a
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• pp.99-102
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• 1999

• Polymer(Korea)
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• v.24 no.5
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• pp.690-700
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• 2000

In this study, an elastomer-assistered compression molding process was investigated by experiments as well as modeling for the long-fiber reinforced thermoset composites. The consolidation pressure generated by fixed-volume and variable-volume conditions was thermodynamically derived for both elastomer and curing prepregs, and was compared with the pressure measured during curing of epoxy matrix. Exhibiting non-linear viscoelastic characteristics in the compressive stress-strain tests, the measured stress was well compared with a modifed KWW (Kohlrausch-Williame-Watts) equation, which is based on the Maxwell viscoelastic model. Using the developed model equations, the consolidation pressure generated by the elastomer was successfully predicted for the compression molding process of thermoset composite materials in tile closed mold system.

• The Korean Journal of Rheology
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• v.10 no.2
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• pp.92-97
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• 1998

열잠재성 경화제인 N-benzylpyrazinium hexafluoroantimonate (BPH)를 이용하여 함 량에 따른 DGEBA계 에폭시 수지의 경화반응에서의 유변학적 특서 및 반응속도를 연구하 였다. 경화시의 활성화 에너지를 Barrett 방법을 이용한 동적 DSC 측정방법으로 조사 하였 다. DSC 실험 결과 BPH의 함량이 증가할수록 활성화 에너지는 감소함을 알수 있었다. Rheomter를 이용하여 DGEBA/BPH 계의 유변학적 특성을 등온경화와 tdmdhsrud화 조건하 에서 살펴보았다. BPH의 함량이 증가함에 따라 겔화점 도달시간 빠르게 나타나는데 이는 낮아진 활성화 에너지에 기인한 것으로 사료된다. 두 번째 damping 피크를 이용하여 유리 화점을 측정하여 Time-Temperature-Transformation (T-T-T) cure diagram을 작성한 결 과 열잠재성 경화제의 특성인 일정온도 이상에서 활성이 나타남을 확인할수있었다.

• Journal of the Korean Vacuum Society
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• v.7 no.3
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• pp.229-236
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• 1998

In this paper, thin films of Polyimide (PI) were fabricated by vapor deposition polymerization method (VDPM) of dry processes. The film's properties with curing temperature and electrical properties were studies. The synthesis of hexafluoroisopropyliden-2,2-bis[phthalic anhydride](6FDA) and 4, 4'-diamino diphenyl ether (DDE) was carried out by vapor deposition polymerization(VDP) with the same deposition rate. The evaporation temperature of 6FDA and DDE were $214^{\circ}C$ and $137^{\circ}C$, respectively, so as to preserve balance of stoichiometry. The polymic acid (PAA) made by VDPM were changed to PI by thermal curing. The uniformity and density of PI thin films were increased according to increasing curing temperature. The relative permittivity and dissipation loss factor were 3.7 and 0.008 at the frequency of 100Hz~200KHz, respectively, for the fabricated in the curing temperature of $300^{\circ}C$. Also, the resistivity was about 1.05$\times$$ 10^{15}$$\Omega$cm at $30^{\circ}C$.

• Proceedings of the KAIS Fall Conference
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• 2001.05a
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• pp.73-75
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• 2001

본 연구에서는 무용제 타입의 알킬(alkyl)기를 가진 친수성 4차 암모늄염인 대전방지제(Ultramer 5530)를 합성, 유/무광 수용성 수지와 배합하여 PVC 바닥재에 열경화 코팅을 행하였다. 대전방지 코팅액은 Ultramer 5530을 광택조절이 가능한 유/무광 수용성 수지에 무게 기준으로 5-20 wt%(이하 ‘part’로 표기)범위로 첨가, 배합하여 제조하였다. 대전방지 코팅 처리전 PVC 바닥재의 표면저항은 10/sup 12/Ω이었으나 코팅 후 표면저항은 유광 수지의 경우 최대 10/sup 8/Ω, 무광 수지의 경우 최대 10/sup 6/Ω까지 감소하였다. 유/무광 수지 모두 경화조건에 관계없이 일반적으로 Ultramer 5530의 첨가량이 증가할수록 코팅된 PVC 바닥재의 표면저항은 현저히 감소하였다. 경화온도 l00℃에서 1분간 경화한 콜이도막은 Ultramer 5530의 첨가량이 증가함에 따라 전기저항이 현저하게 감소하였으나 경도 및 부착률 등의 코팅도막 물성이 현저히 저하됨을 알 수 있었다. 이러한 물성 저하는 경화온도를 80℃로 낮추고 경화시간을 20분으로 늘리면 해결할 수 있었다. 본 연구결과, PVC 바닥재의 표면에 형성된 코팅도막의 물성은 Ultramer 5530의 첨가량을 8 part로 하고 120℃에서 1분간 열경화를 시켰을 때 가장 좋았다.

• Clean Technology
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• v.16 no.4
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• pp.245-253
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• 2010

Optimum conditions for UV-radiated photopolymerization of unsaturated polyester that could be used as protecting layer of large diameter pipe were investigated in this paper. UV photopolymerization method was selected to solve the problems, arising when thermal polymerization by organic peroxide was used, such as the instability of peroxide initiator, the evolution of volatile organic compound, and thermal deformation of product. Two of the photo-initiators (Irgacure 819 and Darocure 1173) well known for its penetrating ability deep into the polymer layer were selected, and the optimum conditions for photopolymerization (1.5 phr initiator content, 1:1.2 initiator ratio, Ga lamp for UV source) were found from the thermal and mechanical test results of the resultant UP polymers. In addition, composite materials containing UP polymer and glass fiber were tested for hardness, impact strength, and flexural strength to find that the impact strength of composite significantly improved.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.2
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• pp.119-124
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• 2013

In this study, the two-dimensional transient temperature of printed Ag nanoparticle ink during continuous wave laser sintering was calculated. Ag nanoparticle ink was printed on a glass substrate by inkjet printing. Then, a 532-nm continuous wave laser with different laser intensities was irradiated on the printed Ag nanoparticle ink for 60 s. During laser irradiation, the in-situ specific resistance of the sintered ink was measured. To obtain the transient temperature of the sintered ink during the laser sintering process, a two-dimensional transient heat conduction equation was derived by applying the Wiedemann-Franz law. It was found that the specific resistance of the sintered ink decreased with an increase in the sintering temperature of the printed ink.