• 한국표면공학회지
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• 제50권5호
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• pp.373-379
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• 2017

Dry processes like evaporation and sputtering in vacuum chamber are difficult to make a uniform, large area and high quality film on thin PET substrate because of PET degradation and bad adhesion. On the other hand, wet processes like electro or electroless plating have complex processes and require high environmental cost. In this study, we successfully prepared $2{\mu}m$ Zn/Cu/Ni multilayers coated on $12{\mu}m$ polyethylene terephthalate (PET) substrate by using dry-wet mixing processes. Their surface electric resistances were evaluated around $0.2{\Omega}$ by using 4 probe measurements. Furthermore, their corrosion resistance also evaluated by natural potential test and compared with other wet, dry and mixing process samples.

• 한국터널지하공간학회 논문집
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• 제16권3호
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• pp.311-320
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• 2014

화재 시 고강도 콘크리트는 보통강도 콘크리트보다 강도의 감소가 빠르게 나타날 뿐만 아니라 단면손실을 발생시키는 스폴링(spalling)에 취약하다. 본 연구에서는 PET섬유가 혼입된 고강도 세그먼트 콘크리트를 대상으로 ISO834 화재곡선과 RABT 화재곡선 하에서 화재저항성을 평가하였다. 화재저항성을 시험한 결과, PET섬유가 혼입되지 않았을 경우에 ISO834 화재곡선과 RABT 화재곡선 하에서 콘크리트의 단면손실은 약 8 cm, 9.5 cm로 측정되었다. ISO834 화재곡선 하에서 PET섬유가 0.1% 혼입되었을 경우에는 단면손실이 발생하지 않았으나, RABT 화재곡선 하에서는 PET섬유가 0.1% 혼입되었을 경우에는 6.5 cm의 단면손실이 발생하였다. RABT 화재곡선 하에서는 PET섬유가 0.2% 혼입되었을 경우에 단면손실이 발생하지 않았다. 따라서 본 연구에서 사용한 세그먼트 콘크리트는 PET섬유의 혼입량이 0.1%일 때 ISO834 화재곡선 하에서 내화성능을 확보하였으며 RABT 화재곡선 하에서는 PET섬유의 혼입량이 0.2%일 때 내화성능을 가지는 것으로 나타났다. 그러나 단면손실이 발생하지 않았더라도 가열면으로부터 4 cm까지의 손상된 표면의 보수보강이 필요한 것으로 판단된다.

• Bulletin of the Korean Chemical Society
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• 제33권3호
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• pp.833-838
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• 2012

The thermal degradation products of polytrimethylene terephthalate (PTT) obtained by heating the sample in the temperature range of $250-360^{\circ}C$ under non-oxidative conditions was characterized using MALDI-TOF (matrix assisted laser desorption/ionization) mass spectrometry. The structures of the degradation products were determined and the relative compositions were estimated. The MALDI-TOF mass spectra of the thermally degraded PTT sample showed three main series of oligomer products with different end groups, which were carboxyl/carboxyl, carboxyl/allyl, and allyl/allyl. In contrast to the thermal degradation of polyethylene terephthalate (PET), the oligomers containing terephthalic anhydrides were not detected, whereas the formation of oligomers containing the unsaturated allyl ester group was confirmed by mass assignment. From these results, it was concluded that the thermal degradation of PTT proceeds exclusively through the ${\beta}$-CH hydrogen transfer mechanism, which is in accordance with the proposed reaction mechanism for the thermal degradation of polybutylene terephthalate (PBT).

• 한국염색가공학회지
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• 제8권3호
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• pp.36-51
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• 1996

In order to investigate the degradation behavior of PET fabrics, sodium diethylene glycolate (SDEG)-diethylene glycol (DEG) solutions were prepared and PET fabrics were treated in the solution. The dissolution rate constant and apparent activation energy of the PET fabrics were calculated by Eyring's and Arrhenius's equation respectively and measured dyeing properties, moisture and antistatic properties. Then compared SDEG-treated fabrics with NaOH-treated. The results were as follows; 1. PET fabrics decreased their weight in SDEG-DEG solution, and the decreasing rate showed a linear relationship to the treating time at constant temperature and concentration of SDEG-DEG solution. 2. The dissolution rate constant showed a linear relationship to the concentration of SDEGDEG solution and an exponential relationship to treating temperature. 3. Apparent activation energy of dissolution was 23.45 kcal/mol. 4. The K/S values and the ΔL values of fabrics treated with SDEG-DEG solution are higher and lower respectively than fabrics treated with NaOH. 5. SDEG-DEG solution treatment improved fabric's moisture regain and it reached almost maximum at about 40% weight loss. 6. In the both reagent the light, wet and sublimation fastness of fabrics are similar. 7. SDEG-DEG solution gave more electrical discharge effect to the fabrics than that of NaOH. 8. NaOH treated PET microfiber have crater-like surface, while SDEG-DEG solution give bathochromic effect to the PET microfiber because which has wrinkles on the surface.

• 폴리머
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• 제29권5호
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• pp.475-480
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• 2005

폴리(에틸렌 나프탈레이트)(PEN)의 가공 특성 향상을 위하여 윤활제 첨가와 폴리(에틸렌 테레프탈레이트)(PET)와의 블렌딩에 의한 상호에스테르 교환반응 유발에 따른 용융 점도 변화에 대하여 고찰하여 보았다. PEN에 윤활제로 calcium stearate(CaST)를 첨가한 결과, 점도를 낮출 수 있었으나 $2wt\%$ 이상의 CaST첨가는 PEN의 열분해를 촉진하여 기계적 물성이 현저히 감소됨을 확인하였다. PEN에 PET를 $10wt\%$ 첨가하여 상호에스테르 교환반응을 유발시킨 PEN/PET블렌드는 PEN보다 낮은 점도를 가지며 이에 $1wt\%$의 CaST윤활제를 같이 첨가하면 CaST가 윤활제 역할을 하는 동시에 상호에스테르 교환반응 촉진제로 작용하여 추가적인 점도 감소가 일어남을 확인하였다.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2003년도 제27회 추계학술대회
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• pp.44-44
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• 2003

As a basic measurement tool in the areas of animal models of human disease, gene expression and therapy, and drug discovery and development, small animal PET imaging is being used increasingly. An ideal small animal PET should have high sensitivity and high and uniform resolution across the field of view to achieve high image quality. However, the combination of long narrow pixellated crystal array and small ring diameter of small animal PET leads to the degradation of spatial resolution for the source located at off center. This degradation of resolution can be improved by determining the depth of interaction (DOI) in the crystal and by taking into account the information in sorting the coincident events. Among a number of 001 identification schemes, dual layer phsowich detector has been widely investigated by many research groups due to its practicability and effectiveness on extracting DOI information. However, the effects of each crystal length composing dual layer phoswich detector on DOI measurements and image qualities were not fully characterized. In order to minimize the DOI effect, the length of each layer of phoswich detector should be optimized. The aim of this study was to perform simulations using a simulation tool, GATE to design the optimum lengths of crystals composing a dual layer phoswich detector. The simulated small PET system employed LSO front layer LuYAP back layer phoswich detector modules and the module consisted of 8${\times}$8 arrays of dual layer crystals with 2 mm ${\times}$ 2 mm sensitive area coupled to a Hamamatsu R7600 00 M64 PSPMT. Sensitivities and variation of radial resolutions were simulated by varying the length of LSO front layer from 0 to 10 mm while the total length (LSO + LuYAP) was fixed to 20 mm for 10 cm diameter ring scanner. The radial resolution uniformity was markedly improved by using DOI information. There existed the optimal lengths of crystal layers to minimize the variation of radial resolutions. In 10 cm ring scanner configuration, the radial resolution was kept below 3.4 mm over 8 cm FOV while the sensitivity was higher than 7.4% for LSO 5 mm : LuYAP 15 mm phoswich detector. In this study, the optimal length of dual layer phoswich detector was derived to achieve high and uniform radial resolution.

• 폴리머
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• 제24권1호
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• pp.58-64
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• 2000

폴리부틸렌테레프탈레이트 (poly(butylene terephthalate), PBT)와 파라아세톡시벤조산 (p-acetoxybenzoic acid, ABA)의 조성비를 4/6, 5/5, 6/4로 하고, 온도를 각각 250, 260, 27$0^{\circ}C$로 하여 용융 에스테르 교환반응시킴으로써 poly(butylene terephthalate-co-oxybenzoate) (PBOT)를 합성하였다. 이에 대한 양성자 핵자기 공명 분광($^1$H FT-NMR) 분석을 통해서 분자내 서열 분석을 해본 결과 연속된 oxybenzoate 단위의 수는 1.2에서 1.5사이의 값을 가졌다. 이 값은 같은 조성비 및 같은 반응온도에서 합성된 폴리에틸렌테레프탈레이트(poly(ethylene terephthalate), PET)/ABA (PEOT)쌍에 비해 상대적으로 큰 값임을 알 수 있었다. 이와 같은 블록길 이상의 차이는 열분해 거동에 영향을 미치며 그 결과 폴리옥시벤조에이트(POB), PBT 및 PEOT가 1단계의 열분해를 하는 반면 PBOT는 2단계의 열분해 거동을 나타내었다. 또한 PBOT는 PBT-rich 상, PBT와 ABA의 랜덤분포 상 및 ABA-rich 상의 3상 구조를 가지는 것으로 추측되었다.

• Macromolecular Research
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• 제17권3호
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• pp.149-155
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• 2009

The thermal decomposition behavior and degradation characteristics off our different thermotropic liquid crystalline polymers (TLCPs) were studied. The thermal decomposition behavior was determined by means of thermogravimetric analysis (TGA) at different heating rates in nitrogen and air. The order of the thermal stability was as follows: multi-aromatic polyester > hydroxybenzoic acid (HBA)/hydroxynaphthoic acid (HNA) copolyester > HNA/hydroxyl acetaniline (HAA)/terephthalic acid (TA) copolyester > HBA/Poly(ethylene terephthalate) (PET) copolyester. The activation energies of the thermal degradation were calculated by four multiple heating rate methods: Flynn-Wall, Friedman, Kissinger, and Kim-Park. The Flynn-Wall and Kim-Park methods were the most suitable methods to calculate the activation energy. Samples were exposed to an accelerated degradation test (ADT), under fixed conditions of heat ($63{\pm}3^{\circ}C$), humidity ($30{\pm}4%$) and Xenon arc radiation ($1.10\;W/m^2$), and the changes in surface morphology and color difference with time were determined. The TLCPs decomposed, discolored and cracked upon exposure to ultraviolet radiation.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 2002년도 추계 학술발표회 논문집
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• pp.185-186
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• 2002

폐 플라스틱은 석유 물질인 탄화수소로 구성하고 있지만 효과적으로 재활용되지 못하고 대부분 매립, 소각 등의 방법으로 처리하고 있다. 플라스틱은 다양한 용도로 사용되기 때문에 플라스틱의 이용과 소비의 증가는 필연적이다. 예로 미국 가정의 폐 플라스틱은 63% 폴리에틸렌, 11% 폴리프로필렌, 11% 폴리스타이렌, 7% PET 그리고 7% PVC가 발생되는데 이들 화합물 구조가 포화탄화수소형이기 때문에 70% 정도가 방향족 화합물인 석탄에 비해 수소첨가 반응이 요구되지 않는다.(중략)

• Korean Chemical Engineering Research
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• 제50권6호
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• pp.1015-1020
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• 2012

석탄 및 pet coke (petroleum coke)는 그 이용이 제한적이지만 공급이 풍부한 에너지원이므로, 가스화공정에 적용하여 고급연료인 수소나 액체연료를 생산할 수 있다. 본 연구에서는 열천칭반응기와 실험실규모의 유동층반응기(내경 0.02 m, 높이 0.6 m)에서 갈탄, 무연탄, pet coke의 수증기 가스화 반응특성을 조사하였다. 가스화 온도 $600{\sim}900^{\circ}C$, 수증기 분압 0.15~0.95 atm 및 수증기/연료 비의 조업변수가 가스화반응속도 및 생성가스의 발열량에 미치는 영향을 조사하였다. 기체-고체 반응모델로서 modified volumetric reaction model을 적용하여 가스화반응의 거동을 묘사하고 kinetic 인자들을 도출하였다. 가스화 반응온도가 높을수록 생성가스 중의 수소농도와 가스의 발열량은 증가하였다. 생성가스 발열량은 무연탄 > 갈탄 > pet coke의 순으로 높게 나타났는데, 반응온도 $900^{\circ}C$, 수증기분압 95%의 조건에서 10.0 > 6.9 > 5.7 $MJ/m^3$로 각각 얻어졌다. 본 연구를 통하여 갈탄과 pet coke에 대해 가스화공정의 잠재적인 연료로서의 가능성을 확인하였다.