• 한국환경과학회지
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• 제27권11호
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• pp.1023-1028
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• 2018

Shape memory materials are widely used in high-tech industries. Although shape memory polymers have been developed, they have a disadvantage, only unidirectional resilience. Shape memory polymers with bi-directional recovery resilience have been actively studied. In this study, a bidirectional shape memory polyurethane was synthesized using poly(${\varepsilon}$-caprolactone) diol, methylene dicyclohexyl diisocyanate, and hydroxyethyl acrylate. The first physical curing occurred between hard segments and hydrogen bondings when the solution was dried. The second curing in acrylate groups was performed by UV exposure. A degree of curing was analyzed by infrared spectroscopy. The shape memory properties of 2 step-cured polyurethanes were investigated as a function of UV curing time.

• 정보저장시스템학회논문집
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• 제11권2호
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• pp.36-40
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• 2015

The demand for flexible devices including solar cells, memories and batteries has increased rapidly over the past decades. In most flexible devices, polymer-based materials are used to enable the mechanical deformations such as bending or folding. Shape Memory Polymers (SMPs) is a high molecular compound polymer with flexibility and shape recovery characteristics. In this work, flexible shape memory device was fabricated by simply coating the conducting material, carbon nano-tube (CNT), on a shape memory polymer. Furthermore, durability of the device under various type of mechanical deformations was assessed. It is believed that the result of this work will aid in realization of a stretchable and wearable electronic device for practical applications.

• 한국항공우주학회지
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• 제45권12호
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• pp.1007-1012
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• 2017

본 연구에서는 우주 안테나 설계용 형상기억 폴리머 시편의 전개 시험을 수행하였다. Poly(cyclooctene)을 dicumyl peroxide를 이용하여 가교시켜 PCO 형상기억 폴리머를 제조하고, 이를 이용하여 지름이 120 mm인 전개형 안테나의 축소 모델을 제작하였다. 전개 성능 시험을 위하여 원형 형태의 형상기억 폴리머 시편을 반으로 접어 임시 형상을 만든 후 두 개의 히터로 형상기억 폴리머의 유리 전이 온도보다 $15^{\circ}C$ 높은 온도로 시편을 가열하였다. 먼저 시편을 수평 설치하여 전개 실험을 수행하였다. 시편의 전개 영상을 디지털 카메라를 사용하여 촬영한 후 트래커 프로그램을 이용하여 분석하였다. 중력의 효과를 최소화하기 위하여 수직 설치하여 다시 실험을 수행하였다. 두 실험의 결과를 비교하여 형상기억 폴리머 시편의 전개 성능을 고찰하였다.

• Elastomers and Composites
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• 제45권3호
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• pp.188-198
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• 2010

형상 기억 고분자(shape memory polymers, SMPs)는 일정한 온도 또는 특정 자극이 주어졌을 때 가해진 일시적인 변형으로부터 처음 상태로 되돌아 오는 고분자를 말한다. 이러한 형상 기억 고분자는 각종 산업에서 자가 조립 또는 자가 수리가 가능한 스마트 고분자로 분류되어 고부가가치를 지니고 있다. 특히 형상 기억 고분자의 방열 성능, 전기 전도 성능, 물리적 성능, 광학 성능 등은 다양한 충전제를 도입함으로써 향상될 수 있다. 본 논문에서는 형상 기억 고분자의 기본 원리 및 최근의 형상 기억 고분자 나노 복합재료에 대해 알아본다.

• 대한기계학회논문집A
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• 제21권10호
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• pp.1609-1618
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• 1997

Thermo-mechanical behaviors of polymer matrix composite(PMC) with continuous TiNi fiber are studied using theoretical analysis with 1-D analytical model and numerical analysis with 2-D multi-fiber finite element(FE) model. It is found that both compressive stress in matrix and tensile stress in TiNi fiber are the source of strengthening mechanisms and thermo-mechanical coupling. Thermal expansion of continuous TiNi fiber reinforced PMC has been compared with various mechanical behaviors as a function of fiber volume fraction, degree of pre-strain and modulus ratio between TiNi fiber and polymer matrix. Based on the concept of so-called shape memory composite(SMC) with a permanent shape memory effect, the critical modulus ratio is determined to obtain a smart composite with no or minimum thermal deformation. The critical modulus ratio should be a major factor for design and manufacturing of SMC.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2005년도 추계종합학술대회
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• pp.825-828
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• 2005

In this paper, we propose a new nonvolatile unit memory cell and proposal peripheral circuit using the polymer material. Memory that relies on bistable behavior- having tow states associated with different resistances at the same applied voltage - has attracted much interest because of its nonvolatile properties. Such memory may also have other merits, including simplicity of structure and manufacturing, and the small size of memory cells. We have plotted the load line graphs for the use of a polymer memory character, hence we have designed in the band-gap reference shape of a write/erase drive, and then designed in the 2-stage differential amplifier shape of a sense amplifier in the consideration of a low current characteristic of a polymer memory cell. The simulation result shows that is has high gain about 80dB by sensing the very small current.

• Fibers and Polymers
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• 제7권4호
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• pp.328-332
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• 2006

Poly(ethylene terephthalate) (PET) and poly(ethylene glycol) (PEG) copolymers cross-linked with pentaerythritol, a four-way cross-linker, are prepared to compare their mechanical and shape memory properties with the one cross-linked by glycerol. Composition of PEG and pentaerythritol is varied to search for the one with the best mechanical and shape memory properties. The highest shape recovery rate is observed for the copolymer composed of 30 mol% PEG-200 and 2.5 mol% pentaerythritol. Four-way cross-linking by pentaerythritol significantly improves shape recovery rate and retention of high shape recovery rate after repeated use compared to the one cross-linked by glycerol, a three-way cross-linker, and difference and advantage of additional cross-linking point are discussed.

• Composites Research
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• 제31권6호
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• pp.347-354
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• 2018

형상기억고분자 복합재료는 가볍고, 변형률이 크며, 좋은 가공성과 비용적인 측면에서의 장점으로 우주환경에서 사용되는 전개형 안테나 재료로의 활용이 검토되고 있다. 본 연구에서는 탄소나노튜브를 보강재로 하여 물성이 향상된 형상기억고분자 복합재료를 제조하고, 이를 사용하여 전개형 안테나를 제작하였다. 탄소나노튜브를 형상기억고분자 기지재 안에 분산시키기 위해 다양한 방법이 사용되었고 물성적인 측면에서 우수한 분산 방법을 탐색하였다. 이렇게 제조된 형상기억고분자 복합재료의 형상기억거동을 평가하였고 형상기억고분자 복합재료 안테나의 전개 거동을 분석하였다.

• 제어로봇시스템학회논문지
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• 제10권11호
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• pp.976-980
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• 2004

This study has introduced how to make conducting shape memory polyurethane(CSMPu) as a possible application to smart actuators. Different from conventional polyurethane, CSMPu can have a high conductivity and then electric power supplies enough energy to deform. To prepare conducting polyurethane, carbon nanotubes were incorporated into shape memory polyurethane. Basic experiments to reveal its characteristics have been conducted for a development of actuators. From the results conducted in the present study, optimized conditions for the process of actuating deformation were found. Thermo-electric characteristics such as the relation between temperature and specific resistance and trend curves of resistance variations according to elongations were measured. These data provided a strong possibility of CSMPu as a smart actuator.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 추계학술대회 논문집
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• pp.809-810
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• 2012