• Macromolecular Research
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• 제12권6호
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• pp.564-572
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• 2004

Modem applications could benefit from multifunctional materials having anisotropic optical, electrical, thermal, or mechanical properties, especially when coupled with locally controlled distribution of the directional response. Such materials are difficult to engineer by conventional methods, but the electric field-aided technology presented herein is able to locally tailor electroactive composites. Applying an electric field to a polymer in its liquid state allows the orientation of chain- or fiber-like inclusions or phases from what was originally an isotropic material. Such composites can be formed from liquid solutions, melts, or mixtures of pre-polymers and cross-linking agents. Upon curing, a 'created composite' results; it consists of these 'pseudofibers' embedded in a matrix. One can also create oriented composites from embedded spheres, flakes, or fiber-like shapes in a liquid plastic. Orientation of the externally applied electric field defines the orientation of the field-aided self-assembled composites. The strength and duration of exposure of the electric field control the degree of anisotropy created. Results of electromechanical testing of these modified materials, which are relevant to sensing and actuation applications, are presented. The materials' micro/nanostructures were analyzed using microscopy and X-ray diffraction techniques.

• 한국세라믹학회지
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• 제37권8호
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• pp.805-810
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• 2000

The formation, microstructure and properties of MoSi2/SiC ceramic composites by polymer pyrolysis were investigated for the application of heating element material. Polymethylsiloxanes were mixed with Si, SiC, MoSi2 as filler and ceramic composites prepared by pyrolysis in N2 atmosphere at 1320~145$0^{\circ}C$ were studied. Dimensional change, density variation and phases were analyzed and correlated to the resulting material properties. Microstructures of ceramic composite prepared by polymer pyrolysis were composed of MoSi2, SiC and silicon oxycarbide glass matrix. Depending on the pyrolysis conditions, ceramic composites with a density of 86~90 TD%, a fracture strength of 213~284 MPa, a thermal expansion coefficient of 4~7$\times$10-6 were obtained. The electrical resistivity of the specimen decreased with increasing of temperature up to 50$0^{\circ}C$.

• 폴리머
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• 제32권4호
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• pp.353-358
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• 2008

EPDM에 maleic anhydride를 그래프트시켜 말레화 EPDM(MEPDM)을 제조하고 여기에 양 말단에 hydroxyl기를 갖는 $\alpha$,$\omega$-poly(dimethylsiloxane)(PDMS)을 반응시켜 MEPDM-g-PDMS 공중합체를 제조하였다. MEPDM-g-PDMS와 HDFE 및 4-ethoxybenzoic acid로 표면처리된 MWCNT를 internal mixer에 가하고 $180^{\circ}C$에서 컴파운딩하여 MEPDM-g-PDMS/HDPE/CNT 복합체를 제조하였다. 복합체에서 CNT의 모폴로지를 전자현미경으로 측정한 결과 표면처리된 CNT를 사용한 경우가 분산이 균일하게 이루어졌으며 입자의 응집현상도 감소되는 것으로 나타났다. 온도변화에 따른 전기저항은 용융온도부근에서 전기저항이 급격히 증가하였으며 EtO-CNT의 함량을 15%로 하여 제조한 복합체의 경우가 PTC intensity가 2.3으로 가장 우수한 PTC 특성을 나타내었다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.350-354
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• 2009

In this work, polymer - inorganic composites have prepared using polymer such as polyethylene glycol (PEG)/poly (methyl methacrylate, PMMA) and inorganic nanofillers materials such as TiO2 nanotubes (TiNTs)/carbon nanotubes (CNTs). The extensive structural, morphological and ionic properties revealed that the high surface area and tubular feature of nanofillers improved the interaction and cross-linking to polymer matrix which is significantly enhanced the ionic conductivity and electrical properties of composite electrolytes. Comparably high conversion efficiency ~4.5% has been observed by using the newly prepared PEG-TiNTs composite solid electrolyte as compared with PMMA-CNTs electrolyte based DSSCs (~3%). The detailed comparative properties would be discussed in term of their structural, morphology, ionic and photovoltaic properties.

• Composites Research
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• 제27권3호
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• pp.90-95
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• 2014

복합재료의 경화 시 발생하는 수축 변형률은 복합재료 구조물 내에 잔류응력을 발생시키며 이러한 잔류응력은 spring-in, spring-out, warpage와 같은 구조물 변형의 원인이 된다. 본 연구에서는 Hexcel사의 "Hexply M21EV/34%/UD268NFS/IMA-12K" prepreg를 사용하였다. 시험편의 경화에 따른 cure shrinkage 변화를 DSC(differential scanning calorimetry)와 TMA(thermomechanical analyzer)를 이용하여 측정하였다. 수지의 수축률은 $140{\sim}240^{\circ}C$ 구간에서 $20^{\circ}C$ 간격으로 질소 분위기에서 측정하였다. 경화도는 dynamic과 isothermal DSC scanning을 통하여 측정된 반응열을 이용하여 산출하였으며, DSC 시험은 Argon 분위기에서 수행하였다. 시험결과, 열경화성 수지는 27~80% 경화도에서 급격한 수축이 일어났으며, 경화온도가 높을수록 더 낮은 경화도에서 수축이 시작되는 것을 알 수 있었다.

• 폴리머
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• 제30권2호
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• pp.135-139
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• 2006

인체 뼈의 주성분인 수산화인회석(hydroxyapatite, HAP)이 충전된 고분자 복합체를 제조하고 이들의 치과적 물성을 분석하여 치과용 수복재료로의 응용성을 확인하고자 하였다. 복합체 제조에 사용된 기질인 아크릴계 단량체는 가시광선으로 경화시켰다. 실험 결과, HAP는 무게비로 65%까지 첨가되었으며 중합깊이는 6.0 mm 정도로서 일반적 치과용 수복재료로의 응용이 가능함을 확인하였다. 제조된 고분자 복합체의 중합전환율은 HHP 첨가량이 늘어날수록 약간 감소하였으며 중합수축률은 HAP 변화량에의 의존성이 거의 없었다. 복합체의 기계적 물성은 HAP함량이 증가할수록 간접인장강도는 증가하였고 굴곡강도는 큰 변화가 없었다. 그러나 그 값들은 치의학에서 규정한 값들을 상회하여 치과용 재료로의 응용 가능성이 매우 높음을 확인할 수 있었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 C
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• pp.1403-1405
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• 1994

In this study, the piezoelectric transducers with 1-3 connectivity have maded. A piezoelectric ceramic PZT prepared by Wet-Dry Combination method is used as a filler in Eccogel polymer matrix. The pulse-echo response for 1-3 type composite transducers were carried out in water. It was observed that the transmitting and receiving sensitivity of 1-3 type composite transducers were improved in comparison with that or solid PZT transducer. The reason is for that 1-3 composites have a hish piezoelectric voltage coefficients, The period of pulse-echo response for the transducer is in a good agreement with the resonant frequency of self-maded composite transducer.

• Elastomers and Composites
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• 제33권5호
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• pp.355-362
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• 1998

전도성 충전제인 카본블랙이 미치는 영향을 올바로 이해하므로서 전도성 카본블랙을 충전하여 도전성 고분자 복합재료를 제조하고자 하였다. 고분자 수지로 ABS(Acrylonitrile Butadiene Styrene copolymer), PC(Polycabonate), PC/ABS 를 사용하여 전도성 카본블랙 3종류를 사용하여 비교하였다. 실험결과 섬유사슬모양의 전도성 카본블랙을 충전한 PC는 상당히 가능성을 보였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계합동학술대회 논문집
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• pp.224-228
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• 2002

In this study, the piezoelectric ceramics PZT powder was synthesized by the Wet-Dry combination method. Flexible 1-3 type composite specimens were fabricated with the piezoceramics PZT filler phase and Eccogel polymer matrix phase. This paper represents the pulse-echo response of the 1-3 type composite transducer to check it out to investigate a basic property regarding a level limit switch. The acoustic impedance of 1-3 type composite was improved than that of single phase PZT ceramics. The pulse-echo response of transducer fabricated with the self-made 1-3 type composites resonator was better than that of the solid PZT transducer.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 B
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• pp.727-729
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• 1992

In this study, the piezoelectric composites with 1-3 connectivity have been studied. A piezoelectric ceramics PZT prepared by Flux method is used as a filler in a epoxy Eccogel polymer matrix. The piezoelectric coefficients were increased as PZT volume% increases, and resonance frequency was moved to lower frequency as the sample thickness increased. The acoustic matching impedance with water is lowered than single phase PZT ceramics.