• 대한치과기공학회지
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• 제38권3호
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• pp.193-199
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• 2016

Purpose: The purpose of this study was to know of photopolymerization effect of self-etch dual-cured resin cement on different transmittance and thickness of zirconia disks. Methods: The two types of transparent and opaque zirconia speciments were prepared. The five speciments of each groups were seperated with 0.5mm and 1.0mm thickness. Degree of conversion(DC) were studied by FT-IR spectroscopy using ATR method before and after irradidaion for 40 sec. Results: The relative DC was showed the higher results of ZS5 as compared with ZS10 (p < 0.05). And OP5 and OP10 were lower results than ZS10 (p < 0.05). Conclusion: The photopolymerization effect of dual-cured resin cement were affected by the transmittance and thickness of zirconia.

• Bulletin of the Korean Chemical Society
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• 제32권3호
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• pp.993-999
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• 2011

The photoreactive prepolymers with multifunctional cinnamate and bisphenol Atype cinnamate groups that could perform photodimerization without photoinitiators were synthesized by the reaction of t-cinnamic acids (CAs) and epoxy resins. Their photocure reaction rates and the extent of reaction conversion were measured with Fourier transform infrared spectroscopy, and these increased with the intensity of UVirradiation. The experimental data of these reaction rates showed the characteristics of nth-order kinetics reaction, and all kinetic constants of each photoreactive polymer with this equation were summarized. Although the GTR-1800-HCA and KWG1-EP-HCA with hydroxyl group substituted cinnamate showed lower reaction conversion rates and rate constant than GTR-1800-CA and KWG1-EP-CAwith an unsubstituted cinnamate group, GTR-1800-MCAand KWG1-EP-MCAwith methoxy group substituted cinnamate showed similar and higher reaction conversion rates than the former, respectively. These results were explained in terms of segmental mobility for photopolymerization by molecular interactions.

• Current Optics and Photonics
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• 제2권3호
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• pp.286-290
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• 2018

We investigated the dependence of the retardation dispersion on the polarization direction of ultraviolet (UV) light during the photopolymerization of self-organized smectic reactive mesogen (RM) molecules. RM retarder film that was photopolymerized with UV light linearly polarized parallel to the layer plane showed negative dispersion (ND) of retardation for a wide range of UV polymerization temperatures. On the other hand, film that was photopolymerized with unpolarized UV light showed negative dispersion in a narrow range of UV polymerization temperatures. With a certain UV polymerization temperature, the dispersion of retardation was converted from positive to negative, depending on the UV polarization.

• Macromolecular Research
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• 제11권5호
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• pp.311-316
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• 2003

The kinetics of photoinitiated polymerization of dimethacrylate macromonomers have been studied to determine the diffusion-controlled reaction parameters using attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). A predicted kinetic rate expression with a diffusion control factor was employed to estimate an effective rate constant and to define the reaction-controlled and diffusion-controlled regimes in the photopolymerization. An effective rate constant, k$_{e}$, can be obtained from the predicted kinetic rate expression. At the earlier stages of polymerization, the average values of kinetic rate constants do not vary during the reaction time. As the reaction conversion, $\alpha$, reaches the critical conversion, $\alpha$$_{c}$, in the predicted kinetic expression, the reaction becomes to be controlled by diffusion due to the restricted mobility of dimethacrylate macromonomers. A drop in value of effective rate constant causes a drastic decrease of reaction rate at the later stages of polymerization. By determining the effective rate constants, the reaction-controlled and diffusion-controlled regimes were properly defined even in the photopolymerization reaction system.m.m.

• Biotechnology and Bioprocess Engineering:BBE
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• 제8권4호
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• pp.240-245
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• 2003

The use of microfabricated microfluidic devices offers significant advantages over current technologies including fast analysis time and small reagent requirements. In the context of proteomic research, the possibility of using affinity-based separations for prefractionation of samples using microfluidic devices has significant potential. We demonstrate the use of microscale devices to achieve affinity separations of proteins using a device fabricated from borosilicate glass wafers. Photolithography and wet etching are used to pattern individual glass wafers and the wafers are fusion bonded at 650$^{\circ}C$ to obtain enclosed channels. A polymer has been successfully polymerized in situ and used either as a frit for packing beads or, when derivatized with Cibacron Blue 3GA, as a separation matrix. Both of these technologies are based on in situ UV photopolymerization of glycidyl methacrylate (GMA) and trimethylolpropane trimethacrylate (TRIM) in channels.

• 한국광학회지
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• 제9권1호
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• pp.31-37
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• 1998

Acrylamide의 광중합(photopolymerization)반응에 의해 형성되는 acrylamide photopolymer를 제작하고 홀로그램 형성과정을 설명하였다. MB(methylene blue) 색소에 의한 빛의 흡수 및 표백과정과 TEA(triethanolamine)에 의해 라디칼중합을 하는 acrylamide 중합과정에 대해 자세히 논하였다. Beer-Lambert의 광화학 표백 모델(photochemical bleaching model)을 이용하여, photopolymer의 흡수곁수와 표백률상수(bleaching rate constant)를 구하였다. 그리고 acrylamide photopolymer의 홀로그램 특성에 기여하는 홑몸체(monomer)의 양과 회절효율과의 관계 및 노출량에 따른 회절효율을 측정하였다. 고분자 결정(polymer crystal)의 grain에 의한 산란효과와 정착(fixing)방법에 대해서도 논하였다.

• 대한치과의사협회지
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• 제57권3호
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• pp.175-184
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• 2019

Increasing the aesthetic needs of patients and decreasing the use of amalgam had led to increased demand for dental resin composite. Thereby, light curing unit (LCU) has become an essential equipment in dental clinic. To ensure long-term prognosis of photopolymerized materials, LCU should have a uniform and consistent radiant output and an emission spectrum that includes the active wavelength range of photoinitiators. In addition, when the correct use and thorough maintenance and repair of LCU are performed, the higher success rate of restoration using photopolymerization materials will be achieved.

• 접착 및 계면
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• 제13권1호
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• pp.38-44
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• 2012

본 연구는 왁스를 함유한 자외선 경화형 코팅제의 경화 물성, 표면 모폴로지, 코팅 표면 물성을 Photo-DSC, SEM, 진자경도, 연필경도 및 광택도를 이용하여 평가하였으며, 특히 왁스의 종류(파라핀 왁스, PE 왁스)에 따른 제반 코팅 물성을 조사하였다. 그 결과 왁스의 종류는 코팅 도막의 광택도와 표면 경도에 큰 영향을 주는 것으로 나타났으며, 유동성이 우수하며 부드러운 고체상의 파라핀 왁스를 사용한 경우에는 저광택의 소광성을 보여주었다. Photo-DSC의 ${\Delta}H$는 왁스를 함유한 코팅 시스템이 함유하지 않은 시스템 보다 높게 나타났는데, 특히 파라핀 왁스를 사용한 경우의 ${\Delta}H$가 PE 왁스를 사용한 경우에 비해 높게 나타났다. 이는 파라핀 왁스가 PE 왁스에 비해 더 효과적으로 공기 중의 산소를 차단하여 경화성이 높아진 것임을 의미한다. 또한 왁스의 산소 차단 효과는 경화속도와 밀접한 관계가 있는 것으로 확인되었다.

• 폴리머
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• 제31권2호
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• pp.153-159
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• 2007

생분해성 분자 날인 고분자는 바이오센서 약물 전달 등의 생의학적 분야에 적응이 가능하다. 그러므로, 본 연구에서는 생분해성 고분자인 $poly(\varepsilon-caprolactone)$ (PCL) 매크로머를 가교제로 사용하여 theophylline 분자 날인 고분자를 광중합을 통해 제조하고 물성을 조사하였다. PCL 매크로머는 말단에 아크릴기를 갖도록 합성하였으며 FT-IR과 $^1H-NMR$로 확인하였다. PCL 매크로머의 합성수율은 약 78 mol%였다. Theophylline의 제거 및 재결합 실험은 UV/Vis분광기를 이용하여 용액 내 theophylline의 농도를 확인함으로써 이루어졌다. Theophylline분자 날인 고분자의 생분해성 실험을 $37^{\circ}C$의 PBS 용액 내에서 진행한 결과 우수한 생분해성을 보였다.

• 청정기술
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• 제16권4호
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• pp.245-253
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• 2010

대구경 강관 표면 보호를 위해 사용되는 필라멘트 와인딩 공정에 불포화 폴리에스터 (unsaturated polyester: UP)를 이용한 자외선 (ultraviolet) 경화 방법을 적용하고자, UP를 이용한 최적의 UV 경화 조건을 찾아보았다. 기존의 유기계 과산화물을 개시제로 사용한 열경화 방법에서는 개시제의 불안정성, 휘발성 유기물 발생, 열에 약한 대상물질의 변형 등 문제점이 발생하므로 이에 대한 개선책으로 UV 경화방법을 시도하였다. UV 경화에 사용되는 다양한 개시제 중에서 비교적 침투력이 높아서 두꺼운 고분자 층 형성이 가능한 개시제 2 종(Irgacure 819 및 Darocure 1173)을 선정하여 이들의 조합비율에 따라 경화된 UP 고분자에 대한 열역학적, 기계적 물성을 비교 분석하여 우수한 경화조건 (개시제 함량 1.5 phr, 혼합 비율 1:1.2, UV 램프로는 갈륨램프)을 찾아내었다. 또한 UP 광경화수지의 경도, 충격강도, 굴곡강도 향상을 위해 유리섬유를 수지 내에 적층하여 복합재료를 제조하고 이들의 특성을 비교한 결과 충격강도가 매우 향상되었다.