• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
• /
• pp.548-548
• /
• 2012

Thermomechanical and surface chemical properties of composite films of poly(D, L-lactic-co-glycolic acid) (PLGA) were significantly improved by the addition of graphene oxide (GO) nanosheets as nanoscale fillers to the PLGA polymer matrix. Enhanced thermomechanical properties of the PLGA/GO (2 wt.%) composite film, including an increase in the crystallization temperature and reduction in the weight loss, were observed. The tensile modulus of a composite film with increased GO fraction was presumably enhanced due to strong chemical bonding between the GO nanosheets and PLGA matrix. Enhanced hydrophilicity of the composite film due to embedded GO nanosheets also improved the biocompatibility of the composite film. Improved thermomechanical properties and biocompatibility of the PLGA composite films embedded with GO nanosheets may be applicable to biomedical applications such as scaffolds.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2011년도 제40회 동계학술대회 초록집
• /
• pp.478-478
• /
• 2011

The thermomechanical and surface chemical properties of nanocomposite of poly( D, L-actic-co-glycolic acid) (PLGA) were improved significant due to concentration of graphene oxide (GO) nanosheets as nanoscale fillers to PLGA film. Thermomechanical properties of the PLGA/GO (2wt.-%.) nanocomposite were decreased crystallization and melting temperature, weight loss. The storage and loss moduli of the nanocomposite were enhanced by chemical bonding between the oxygenated functional groups of the GO nanosheets and the polymer chains in the PLGA matrix. Enhanced hydrophilicity of nanocomposite caused by embedded GO nanosheets also improved for good biocompatibility. Our findings indicate that thermomechanical properties and biocompatibility of nanocomposite embedded with GO nanosheets are attractive candidates for use in biomedical applications such as scaffolds.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
• /
• pp.376-376
• /
• 2016

Poly(ethylene oxide) (PEO)/functionalized bacterial cellulose nanowhiskers (f-BCNW) (0.1 wt%) composite nanofibers were fabricated by electrospinning process and the thermomechanical properties were significantly enhanced more than the PEO and PEO/bacterial cellulose nanowhiskers (BCNW) (0.1 wt%) composite nanofibers. The functionalization of BCNW (f-BCNW) was performed by microwave plasma treatment for effects of nitrogen functionalization of chemically-driven BCNW. The N-containing functional groups of f-BCNW enhanced chemical bonding between the hydroxyl groups of the polymer chains in the PEO matrix and diameter size of PEO/f-BCNW (0.1 wt%) composite nanofibers were decreased more than PEO and PEO/BCNW (0.1 wt%) composite nanofibers on the same concentration. The strong interfacial interactions between the f-BCNW nanofillers and polymer matrix were improved the thermomechanical properties such as crystallization temperature, weight loss and glass transition temperature (Tg) compared to PEO and PEO/BCNW composites nanofibers. The results demonstrated that N2 plasma treatment of BCNW is very useful in improving thermal stability for bio-applications.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2001년도 춘계학술대회 논문집
• /
• pp.833-836
• /
• 2001

The thermomechanical behaviors of the shape memory alloy were conducted through the finite element analysis of ABAQUS with UMAT user subroutine. The unified thermomechanical constitutive equation suggested by Lagoudas was adapted into the UMAT user subroutine to investigate the characteristics of the shape memory alloy. The three cases were solved to investigate the thermomechanical characteristics of the shape memory alloy. The material properties for the analysis were obtained by DSC and DMA techniques. According to the results, the thermomechanical characteristics, such as a shape memory effect and a pseudoelastic effect, could be obtained through the finite element analysis and the analysis results were revealed to agree well with the experimental results. Therefore, the finite element analysis using UMAT user subroutine is one of prominent analysis techniques to investigate the thermomechnical behaviors of the shape memory alloy quantitatively.

• Journal of Industrial and Engineering Chemistry
• /
• 제67권
• /
• pp.1-11
• /
• 2018

Polymer composites offered broad engineered applications, however their diversity get restricted owing to fluctuations in thermomechanical properties during heating or cooling hence great concern required prior their applications through thermomechanical analysis (TMA). Traditionally, TMA or dilatometry found to be simple, ideal, reliable, sensitive, excellent and basic thermal analytical technique. TMA provides valuable information on thermal expansion, glass transitions temperature (Tg), softening points, composition and phase changes on material of having different geometries simply by applying a constant force as a function of temperature. This compilation highlights the basics and experimental of TMA for both research and technical applications and also provide literature on TMA of polymers, hybrid composites, nanocomposites and their diverse applications.

• 터널과지하공간
• /
• 제4권2호
• /
• pp.102-118
• /
• 1994

Thermomechanical analysis is conducted on the radioactive repository in deep rock mass considering the in-situ stress, excavation and thermal loading of a radioactive waste. Thermomechanical properties of a discontinuous rock mass are estimated by a theoretical method so called sequential analysis. Using the estimated properties as input for finite element analysis, the influence on temperature distribution and thermal stress is analyzed within the scope of 2-dimensional steady state and transient heat transfer and coupled thermal elastic plastic behaviour. Granitic rock mass is taken for this analysis. The analysis is done for two different rock mass conditions, i.e. continuous-homogeneous and highly jointed conditions, for the purpose of comparison. In the case of steady state, the extent of disturbed zone around the storage tunnel due to the heat production of the spent-fuel canister varies depending on the thermomechanical properties of the rock mass. In the case of transient analyses, the response of the jointed rock mass to the thermal loading after radioactive waste disposal varies significantly with time, resulting in dramatic changes in the both size and location of disturbed zone.

• 산업기술연구
• /
• 제1권
• /
• pp.53-60
• /
• 1981

A study has been performed on the effect of TMT(thermomechanical treatment) on the mechanical properties of steel and aluminum alloys. Improvement of the mechanical properties on steel by HTMT is due to refinement of prior austenite grain size, martensite lath size and the distribution of fine carbide precipitates and on aluminum alloy by ITMT is due to grain size refinement, homogeneous distribution of small second phase particles and retardation of the recrystallization.

• 열처리공학회지
• /
• 제4권4호
• /
• pp.24-33
• /
• 1991

The effects of thermomechanical treatments on microstructure and fatigue properties of 7050 Al alloy were investigated. The precipitation kinetics changed to a faster rate due to cold deformation employed in this special TAHA thermomechanical treatments including pre-aging, plastic deformation and two step final-aging. The G.P. zones in the under-aged condition were cut by dislocations and dissolved during the plastic deformation. During the low cycle fatigue, the T6' condition showed cyclic hardening behavior whereas the TMT5, TMT27 and T76 conditions showed cyclic softening at above 0.7% total strain amplitudes. The ${\Delta}K_{th}$ value of TMT27 was improved more than two times, compared with that of T76 condition. The T6' with small shearable precipitates resulted in the markedly high ${\Delta}K_{th}$ value. This is thought to be resulted from dislocation reversibility and roughness-induced crack closure due to planarity of slip.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 1999년도 제3회 압연심포지엄 논문집 압연기술의 미래개척 (Exploitation of Future Rolling Technologies)
• /
• pp.390-398
• /
• 1999

The thermomechanical control process(in hot rolling strip mill) was employed to produce 2.25Cr-1Mo steel, which is to be construction material for the steam generator for power plant. Although the Conventional processes has been the primary means of producing the 2.25Cr-1Mo steel, an alternative method was used to meet the specification of ASTM heat treatment for A387-22-Classl using autotempering after coiling in hot rolling strip mill. The microstructures, tensile properties at various temperatures, and creep-rupture properties have been investigated to compare the properties with those of materials produced by the conventional process and to certify the application of the thermomechanical control process to an actual process of manufacturing 2.25-Cr-1Mo steel, this in turn, will reduce the cost of the process. About 14 to 34% glanular bainite (remainder proetectoid ferrite) formed in a coil, and this variety of volume fraction stems from the different cooling rates, which varies with position of the coil after coiling. Tensile testing from room temperature to 700$^{\circ}C$ indicated that strength increases with test temperature showing peaks at around 600$^{\circ}C$. Creep-rupture properties have been being investigated at the temperature of 500$^{\circ}C$ with 27.5, 32kg/$\textrm{mm}^2$ loads and have showed no rupture for over 1000 hours.

• 폴리머
• /
• 제33권2호
• /
• pp.97-103
• /
• 2009

기능화 탄소나노튜브인 4-cumylphenol-MWNT(CP-MWNT)를 이용하여 초고분자량 폴리에틸렌(ultra high molecular weight polyethylene (UHMWPE))/CP-MWNT 복합체 필름을 용액 삽입법을 이용하여 제조하였다. 0에서 2.00 wt%까지의 서로 다른 CP-MWNT의 농도에 따라 만들어진 복합체 필름의 열적, 기계적, 기체 투과도 및 광학 투명성 등의 변화를 시차주사열량계, 열중량분석기, 전계 방사형 주사전자현미경과 인장시험기를 사용하여 측정하였다 복합체 필름은 기능화된 탄소나노튜브를 소량 첨가하여도 열역학적 특성이 향상되는 것을 확인할 수 있으며 0.50에서 1.00 wt%의 농도에서 최대값을 가진다. CP-MWNT의 농도가 1.00 wt%일 때 필름의 산소 기체 차단성은 최대 향상을 나타내었다. 전체적으로는 CP-MWNT가 첨가된 복합체 필름의 열적-기계적 성질 및 기체 투과도 등은 순수한 UHMWPE보다 더 향상되었다.