• Composites Research
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• 제18권4호
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• pp.21-26
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• 2005

탄소나노튜브 및 탄소나노섬유/에폭시 복합재료의 비파괴 손상감지능 및 응력전달 메카니즘이 전기-미세기계적 실험법을 통하여 조사되었다. 전기-미세기계적 실험법은 균일한 반복하중 하에서 전기저항을 측정함으로써 탄소나노복합재료의 감지반응을 평가하는 것이다. 큰 탄소섬유 부피 분율이 있는 복합재료가 에폭시 자체나 작은 부피 분율에 비하여 매우 큰 인장강도 특성을 보여주었다. 탄소나노섬유 복합재료는 제한된 온도범위 내에서 습도 감지능을 보여주었다. 형상비가 작은 탄소나노섬유 복합재료는 많이 첨가된 부피량에 기인하여 보다 큰 겉보기 탄성계수를 보여 주었다. 열처리된 전기 방사된 PVDF 나노섬유는 증대된 결정화에 기인하여 미처리의 경우보다 큰 기계적 특성을 보여 주었으며, 그 반면에 응력 감지능은 열처리의 경우에 감소를 보여 주었다. 전기 방사된 나노섬유는 또한 응력전달 뿐만 아니라 습도 및 온도에 대한 감지능도 나타내었다. 탄소나노튜브. 탄소나노섬유 및 전기 방사된 PVDF 나노섬유는 나노복합재료의 다기능에 응용할 수 있을 것이다.

• Composites Research
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• 제26권1호
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• pp.14-20
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• 2013

CNT를 포함하는 전기방사된 PVDF를 작동기 제조의 소재로 사용하였다. 기계적, 전기적특성과 함께 작동기 성능을 평가하기 위해 전기화학적 환경 내에서 전기화학 및 작동기 거동을 조사하였다. 전기방사된 시트의 특징 중 하나인 유연함을 가지며 분산이 잘 되어 접촉면이 많은 이점이 있기 때문에 작동기 제작방법으로 적합하다고 생각되었다. 전기방사는 여러 가지 요인들로 방사형태가 각각 다르게 나타났다. 본 연구에서는 콜렉터를 드럼형태를 사용하여 방사된 나노섬유의 방향성을 가지게 하였으며 형태를 확인하기 위해 전자현미경을 통해 나노섬유가 정렬된 형상을 확인하였다. 전자침 X-ray 미세분석기를 사용하여 PVDF내에 CNT가 함침 되어 나노섬유가 정렬 된 상태를 확인하였으며, 이러한 형태가 미치는 기계적, 전기적 물성에 영향을 평가하기 위해 인장시험을 통해 인장강도와 전기 저항도를 측정하였다. 정렬된 방향의 나노섬유 시트가 정렬의 직각 방향의 시트보다 상대적으로 기계적 그리고 전기적 물성이 좋게 나타났다. 전기방사된 CNT/PVDF 나노섬유 시트가 작동기로 사용 되었을 때 캐스팅으로 제작된 PVDF 시트의 작동기보다 좋은 효율을 확인하기 위해 전기화학적 환경 내에서 작동기 시험을 진행하여, 작동기 효율과 전기적 용량을 측정하였다. 전기방사된 CNT/PVDF 나노섬유 시트는 CNT와 PVDF간의 접촉면이 많기 때문에, 우수한 작동성을 나타내었다.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2003년도 가을 학술발표회 논문집
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• pp.271-272
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• 2003

Electrospinning is a novel process for forming fibers with submicron scale diameters through the action of electrical force. In the previous study, we performed study on the ultrafine PVDF nanofiber production in the stable spinning condition. Recently it would be great interest to fabricate IP(inorganic particle) assemblies in nanofibe. since such IP/nanofiber hybrid materials might be used in a nonwoven form as nanowires, medical gauges for bums healing and cell growing, sensors, chemical and gas filteration. (omitted)

• 한국발생생물학회지:발생과생식
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• 제24권2호
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• pp.135-147
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• 2020

Polyvinylidene fluoride (PVDF) is a stable and biocompatible material that has been broadly used in biomedical applications. Due to its piezoelectric property, the electrospun nanofiber of PVDF has been used to culture electroactive cells, such as osteocytes and cardiomyocytes. Here, taking advantage of the piezoelectric property of PVDF, we have fabricated a PVDF nanofiber scaffolds using an electrospinning technique for differentiating human embryonic stem cells (hESCs) into neural precursors (NPs). Surface coating with a peptide derived from vitronectin enables hESCs to firmly adhere onto the nanofiber scaffolds and differentiate into NPs under dual-SMAD inhibition. Our nanofiber scaffolds supported the differentiation of hESCs into SOX1-positive NPs more significantly than Matrigel. The NPs generated on the nanofiber scaffolds could give rise to neurons, astrocytes, and oligodendrocyte precursors. Furthermore, comparative transcriptome analysis revealed the variable expressions of 27 genes in the nanofiber scaffold groups, several of which are highly related to the biological processes required for neural differentiation. These results suggest that a PVDF nanofiber scaffold coated with a vitronectin peptide can serve as a highly efficient and defined culture platform for the neural differentiation of hESCs.

• Macromolecular Research
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• 제16권3호
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• pp.212-217
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• 2008

PVDF ($Kynar^{(R)}$ 761) nanofibers were made by electrospinning with an external voltage of 6-10 kV, a traveling distance of 7-15 cm and a flow rate of 0.4-1 mL/h. Although the mean diameter of the fibers has not changed significantly, the conditions affected the change in diameter distribution. This was attributed to interactions, both attraction and repulsion, between the positive charges on the polymer solutions and the electrically grounded collector. Higher voltages and traveling distance increased the level of attraction between the positive charge on the polymer solution and the electrically grounded collector, resulting in a narrow diameter distribution, In addition, a high flow rate allowed a high population of uniformly charged solutions to travel to the grounded collector, which resulted in a narrow diameter distribution. The optimum conditions for electrospinning of PVDF in DMAc/acetone (3/7 by wt) were a collector voltage of 6 kV, a syringe tip to collector of 7 cm, a flux rate of 0.4 mL/h and 10 kV, 10 cm, 1 mL/h, Since PVDF is widely used as a filtration membrane, it was electrospun on a PET support with a rotating drum as a grounded collector. Surprisingly, some straight nanofibers were separated from the randomly deposited nanofibers. The straight nanofiber area was transparent, while the randomly deposited nanofiber area was opaque. Both straight nanofibers and aligned nanotibers could be obtained by manipulating the PET drum collector. These phenomena were not observed when the support was changed to an Al sheet. This suggests that a pseudo dual collector was generated on the PET sheet. No negative charge was created because the PET sheet was not a conductive material. However, less charge was created when the sheet was not perfectly attached to the metal drum. Hence, the nanotibers jumped from one grounded site to the nearest one, yielding a straight nanofiber.

• Journal of Industrial and Engineering Chemistry
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• 제68권
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• pp.416-424
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• 2018

Oil spill and oily wastewater have now become a serious threat to the freshwater and marine environments. Porous materials with super-hydrophobicity and super-oleophilicity are good candidates for the oil adsorption and oil/water separation. Here, flexible hybrid nanofibrous membrane (FHNM) containing $SiO_2$/polyvinylidene fluoride (PVDF) microspheres was prepared by simultaneous electrospinning and electrospraying. The obtained FHNM combined the flexibility of the nanofiber mat and super-hydrophobicity of the microspheres, which could not be achieved by either only electrospinning or only electrospraying. It was found that when the weight ratio between the $SiO_2$ and PVDF reached a critical value, the $SiO_2$ nanoparticles were present on the PVDF microsphere surface, significantly improving the surface roughness and hence the contact angle of the FHNM. Compared with the pure electrospun PVDF nanofiber mat, most of the FHNMs have a higher oil adsorption capacity. The FHNM could separate the oil with water quickly under the gravity and displayed a high efficiency and good reusability for the oil/water separation. More importantly, the FHNM could not only separate the oil with the pure water but also the corrosive solution including the salt, acid and alkali solution.