• Polymer(Korea)
• /
• v.24 no.4
• /
• pp.477-487
• /
• 2000

A series of poly(L-lactic acid) (PLLA)/poly($\beta$-hydroxynonanoate) (PHN) blend were prepared to study the miscibility and the crystallization behaviors. The thermal behaviors and characterization of PLLA/PHN blends Were studied using differential scanning calorimetry (DSC), XRD and polarizing optical microscopy (POM). The PLLA and PHN are partially miscible in amorphous region. The crystallinity of PLLA increased as the content of PHN increased, and T$_{g}$, T$_{c}$, and T$_{m}$ of PLLA shift as the content of PHN increased. Moreover, the number of PLLA spherulite increased as the content of PHN increased in the POM experiment. Thus, PHN acted as a nucleating agent to PLLA.

• Applied Chemistry for Engineering
• /
• v.17 no.6
• /
• pp.614-618
• /
• 2006

Recycling of asphalt including shingle is much important for economic aspects such as a decrease of treatment cost. This research was carried out in order to process the recycled shingle to asphalt concrete which is a pavement material. Pure asphalt and the mixture of recycled asphalt were tested in terms of the thermal characteristics, viscosity, and penetration. DSC analysis indicates that the thermal characteristics of separate shingle showed similar properties regardless of processing conditions. Melting of asphalt separated from shingle occurred at $170^{\circ}C$. The viscosity and penetration of the 1~5 wt% of mixed recycling asphalt and raw material asphalt are suitable for the pavement material standard.

• Transactions of the Korean hydrogen and new energy society
• /
• v.14 no.3
• /
• pp.258-267
• /
• 2003

A new kind of oxygen carrier material is tested for chemical-looping combustion. NiO, CoO, $Fe_2O_3$ is chosen as metal oxide and YSZ as a binder. Hydrogen fuel is reacted with metal oxide (reduction of metal oxide) and then the reduced metal is successively oxidized by air. Dissolution method is examined to prepare the oxygen carriers. The effects of reaction temperature are measured by a TGA, mechanical strength and regenerability after 10 cycle are examined. $Fe_2O_3/YSZ$ oxygen carrier is bested in mechanical strength and we consider that NiO/YSZ after 3rd cycle are good oxygen carrier in according to reactor design.

• Polymer(Korea)
• /
• v.36 no.3
• /
• pp.275-280
• /
• 2012

Poly(amic acid)s were successfully synthesized from 1,4-bis(4-aminophenoxy)benzene (1,4-APB) or 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane (HFBAPP) with pyromellitic dianhydride (PMDA), 3,3'-4,4'-benzopenonetetracarboxylic dianhydride (BPDA) and $p$-phenylenediamine ($p$-PDA) and then they were effectively converted into polyimide films by thermal imidization. The chemical structure and thermo-mechanical properties of polyimide films were examined using Fourier transform infrared spectroscopy (FTIR), thermo-gravimetric analyzer (TGA), thermo-mechanical analyzer, dynamic mechanical analyzer (DMA) and universal tensile machine (UTM). The moisture absorption, thermal and mechanical properties of polyimide films decreased with increasing the amount of 1,4-APB and HFBAPP. The polyimide films using HFBAPP showed lower properties than that of 1,4-APB at the same ratio, but it displayed better thermal properties and lower moisture absorption at the similar coefficient of thermal expansion (CTE) with a copper. On the basis of our finding, it is concluded that 4-component polyimide films could be utilized for base films for flexible copper clad laminates (FCCL) of flexible printed circuit boards.

• Fire Science and Engineering
• /
• v.22 no.1
• /
• pp.84-92
• /
• 2008

Disclosed is a study related to the thermal characteristics of Pinus densiflora and Quercus dentate identifying the presence of any significant difference in the above trees, which are native to Young Dong Province of Korea, according to different regions of the trees such as branches, barks, living leaves and dead leaves. For this purpose, we have carried out a cone calorimeter test focusing on the variables such as mass loss, heat release, ignition time, flame holding time and concentrations of CO and $CO_2$. The results showed that the total mass loss was greatest in tree branches, whereas the ignition time of dead leaves was fastest both in Pinus densiflora and Quercus dantata. The flame holding times of dead leaves and barks were about $640{\sim}1,016s$ and the total heat release of dead leaves was around 60.1 $MJ/m^2$, twice the total heat release of living leaves. In addition, the maximum exhaust concentrations of CO and $CO_2$ in tree branches of Quercus dentata was 2.82 times higher than those of Pinus densiflora, respectively. From the foregoing, it was confirmed that there exist region-specific differential thermal characteristics in Pinus densiflora and Quercus dentata.

• Polymer(Korea)
• /
• v.33 no.4
• /
• pp.313-318
• /
• 2009

Copolyimides were synthesized from bis (3-aminophenyl) sulfone (APS) and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) containing a fluorine substituent ($-CF_3$) with different mole ratios of 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride (DSDA) containing a sulfone group (-$SO_2$-). The PI films were obtained from poly (amic acid) (PAA) by solution casting through thermal imidization on a glass plate. Wide-angle X-ray diffraction (XRD), scanning electron microscopy (FE-SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), universal tensile machine (UTM) measurements, and UV-Vis spectrometry were used to assess thermo-mechanical properties, morphology, and optical transparency. Thermal properties and optical transparency decreased with increasing DSDA mole fraction. In contrast, mechanical properties increased with increasing DSDA mole fraction. As compared to conventional PI films, however, the PI copolymer films in this work were found to exhibit better optical transparency.

• Composites Research
• /
• v.30 no.3
• /
• pp.215-222
• /
• 2017

The effect of a multi walled carbon nanotubes (MWNCT) on the adhesive properties and thermal properties of epoxy were studied by double lap-shear tests. Epoxy/MWCNT resins were prepared from a different amount of the MWCNT incorporated into the epoxy resins (araldite 2011). Steel plates and carbon fiber reinforced plastics (CFRP) were chosen as materials. Mechanical tests were performed by a universal testing machine (UTM). The analysis of thermal properties were conducted by a thermogravimetric analyzer (TGA) and a differential scanning calorimetry (DSC). The fracture surface morphology was examined using a scanning electron microscopy (SEM) and optical microscope. Compared to neat epoxy, it was found that the mechanical properties of epoxy/MWCNT resins are increased.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1996.11a
• /
• pp.151-156
• /
• 1996

수소동위원소 교환반응에 이용되는 스티렌-디비닐벤젠 고분자 촉매 담체를 제조하였다. 중합반응시 일정한 용매계에서 용매/모노머 함량비와 팽윤제/침전제 함량비를 변화시켜 담체의 표면특성에 미치는 영향을 확인하였다. 가교도가 33%일 경우 용매/모노머가 2.0 이하에서 팽윤제/침전제의 함량비가 증가할수록 10~30$\AA$의 반경을 갖는 기공의 분포가 증가하였다. 담체의 열적안정성을 확인하기 위한 열 중량 분석에서는 온도를 일정한 비율로 단시간에 증가시킬 경우에는 담체의 가교도에 관계없이 35$0^{\circ}C$ 근처에서 거의 유사한 degradation을 보였지만 온도를 매우 천천히 증가시켜 장시간 노출시킬 경우 가교도에 따라서 degradation의 정도와 경향이 다르게 나타남을 확인하였다.

• Electronics and Telecommunications Trends
• /
• v.23 no.5
• /
• pp.111-123
• /
• 2008

플렉시블 기판은 플렉시블 디스플레이의 공정성, 성능, 신뢰성, 가격을 결정하는 가장 중요한 부품으로서 산업적인 주목을 받고 있다. 플렉시블 기판 중에서는 플라스틱이 가공의 용이성, 저중량, 연속공정의 적합성으로 인해 적용이 광범위하게 검토되고 있지만, 광학용 기판으로서는 많은 소재적/공정적 문제점을 안고 있다. 이를 해결하기 위해 플라스틱 기판의 특성(주로 열적 안정성)을 향상시키거나, 플라스틱 기판에 적합한 저온 형성용 유/무기 소재 및 공정을 개발하는 연구가 많이 진행되고 있으나, 수요 업체의 요구수준에는 미치지 못하고 있다. 본 자료에서는 디스플레이용 기판으로서 플라스틱의 문제점을 살펴보고 이를 개선하기 위한 최근의 소재 및 수요 업체의 동향을 알아 본다.

• Fire Science and Engineering
• /
• v.20 no.3 s.63
• /
• pp.35-41
• /
• 2006

In this study, we presented the problems in the insulation cover of 22.9kV transformer bushing through investigating actual conditions. After thermal stress applied to the insulation cover, deterioration patterns, thermogravimetric and infrared characteristics were analyzed, and the results were applied to the cause analysis of accidents and judgement of safety. The insulation covers are used to protect exposed terminals of transformer, but they had improper size and length. Therefore, they could not show efficient insulation function. In case that thermal stress of $150^{\circ}C$ was applied to the insulation covers, plastic insulation covers(A, B, D, E) damaged severely, whereas rubber insulation cover(C) showed normal shapes. In the result of thermogravimetric analysis, the thermal gravity of plastic covers(A) decreased about 33.3% at $307.8^{\circ}C\;to\;405.9^{\circ}C$. and he thermal gravity of rubber covers (C) decreased about 53.7% at $258.8^{\circ}C\;to\;32.9^{\circ}C$. In the result of FT-IR analysis, plastic covers showed peaks characteristic of $CH_2,\;CH_3$, C=O and C=C bonds, whereas rubber covers showed peaks characteristic of OH, $CH_2,\;CH_3$, C=O, C=N and C=C bonds.