• Title, Summary, Keyword: Nanofiber

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Fabrication of Polypyrrole Deposited Poly (vinyl alcohol) Nanofiber Webs by Dip-coating and In situ Polymerization and their Application to Textile Electrode Sensors (Polypyrrole을 증착시킨 Poly(vinyl alcohol) 나노섬유 제조 및 전극용 텍스타일 센서로의 활용 가능성 탐색 -딥 코팅과 현장중합 증착 방식을 중심으로-)

  • Yang, Hyukjoo;Kim, Jaehyun;Lee, Seungsin;Cho, Gilsoo
    • Fashion & Textile Research Journal
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    • v.22 no.3
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    • pp.386-398
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    • 2020
  • This study compared dip-coating and in situ polymerization methods for the development of nanofiber-based E-textile using polypyrrole. Nanofiber webs were fabricated by electrospinning an aqueous poly (vinyl alcohol) (PVA) solution. Subsequently, the PVA nanofiber web underwent thermal treatment to improve water resistance. Dip-coating and in situ polymerization methods were used to deposit polypyrrole on the surfaces of the nanofiber web. An FE-SEM analysis was also conducted to examine specimen surface characteristics along with EDS and FT-IR that analyzed the chemical bonding between polypyrrole and specimens. The line resistance and sheet resistance of the treated specimens were measured. Finally, an electrocardiogram (ECG) was measured with textile sensors made of the polypyrrole-deposited PVA nanofiber webs. The polypyrrole-deposited PVA nanofiber webs fabricated by dip-coating dissolved in the dip-coating solution and indicated damage to the nanofibers. However, in the case of in situ polymerization, polypyrrole nanoparticles were deposited on the surface and inter-web structure of the PVA nanofiber web. The resistance measurements indicated that polypyrrole-deposited PVA nanofiber webs fabricated by in situ polymerization with an average sheet resistance of 5.3 k(Ω/□). Polypyrrole-deposited PVA nanofiber webs fabricated by dip-coating showed an average sheet resistance of 57.3 k(Ω/□). Polypyrrole-deposited PVA nanofibers fabricated by in situ polymerization showed a lower line and sheet resistance; in addition, they detected the electrical activity of the heart during ECG measurements. The electrodes made from polypyrrole-deposited PVA nanofiber webs by in situ polymerization showed the best performance for sensing ECG signals among the evaluated specimens.

Fabrication and Electrical, Thermal and Morphological Properties of Novel Carbon Nanofiber Web/Unsaturated Polyester Composites

  • Kim, Seong-Hwan;Kwon, Oh-Hyeong;Cho, Dong-Hwan
    • Carbon letters
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    • v.11 no.4
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    • pp.285-292
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    • 2010
  • Novel unsaturated polyester composites with PAN-based nanofiber, stabilized PAN nanofiber, and carbonized nanofiber webs have been fabricated, respectively, and the effects of the nanofiber web content on their electrical resistivity, the thermal stability, dynamic storage modulus, and fracture surfaces were studied. The result demonstrated that the introduction of just one single layer (which is corresponding to 2 wt.%) of the carbonized nanofiber web to unsaturated polyester resin (UPE) could contribute to reducing markedly the electrical resistivity of the resin reflecting the percolation threshold, to improving the storage modulus, and to increasing the thermal stability above $350^{\circ}C$. The effect on decreasing the resistivity and increasing the modulus was the greatest at the carbonized PAN nanofiber web content of 8 wt.%, particularly showing that the storage modulus was increased about 257~283% in the measuring temperature range of $-25^{\circ}C$ to $50^{\circ}C$. The result also exhibited that the carbonized PAN nanofibers were distributed uniformly and compactly in the unsaturated polyester, connecting the matrix three-dimensionally through the thickness direction of each specimen. It seemed that such the fiber distribution played a role in reducing the electrical resistivity as well as in improving the dynamic storage modulus.

Changes in Waterproofness and Breathability after Repeated Laundering and Durability of Electrospun Nanofiber Web Laminates (전기방사한 나노섬유 웹 라미네이트 소재의 반복 세탁에 따른 투습방수 성능 변화 및 내구성)

  • Lee, Kyung;Yoon, Bo-Ram;Lee, Seung-Sin
    • Fashion & Textile Research Journal
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    • v.14 no.1
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    • pp.122-129
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    • 2012
  • To develop a waterproof breathable material, we fabricated three kinds of nanofiber web laminates using a massproduced electrospun nanofiber web with different substrates and layer structures. The waterproofness and breathability of nanofiber web laminates were evaluated after repeated launderings and compared with those of conventional waterproof breathable fabrics currently in use, including densely woven fabric, microporous membrane laminated fabric, and coated fabric. The durability of nanofiber web laminates, including adhesion strength, abrasion resistance, tensile strength, and tearing strength, was also assessed and compared with those of conventional waterproof breathable fabrics. The water vapor transmission of nanofiber web laminates increased slightly after repeated launderings, whereas the air permeability somewhat decreased after launderings but still maintained an acceptable level of air permeability. Laundering reduced the resistance to water penetration of nanofiber web laminates, which implies that laminating techniques or substrate materials that could support waterproofness of the laminated structure should be explored. The adhesion strength, abrasion resistance, tensile strength, and tearing strength of nanofiber web laminates were in a range comparable to conventional waterproof breathable materials.

PVDF Nanofiber Scaffold Coated with a Vitronectin Peptide Facilitates the Neural Differentiation of Human Embryonic Stem Cells

  • Jeon, Byeong-Min;Yeon, Gyu-Bum;Goo, Hui-Gwan;Lee, Kyung Eun;Kim, Dae-Sung
    • Development and Reproduction
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    • v.24 no.2
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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.

A Study on Mechanical Properties of Carbon Nanofiber/Epoxy Composites with Dispersion Methods (분산 방법에 따른 탄소나노섬유/에폭시 복합재료의 기계적 물성에 관한 연구)

  • Kong Jin-Woo;Chung Sang-Su;Kim Tae-Wook
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.151-154
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    • 2004
  • Despite of the excellent properties of carbon nanofiber, The properties of carbon nanofiber filled polymer composites were not increased largely. The reason is that it is still difficult to ensure the uniform dispersion of carbon nanofiber in a polymer matrix. In this study, For improvement properties of carbon nanofiber filled epoxy composites, the effect of dispersion was investigated. The compounds were prepared by two methods, solution blending and mechanical mixing. Mixing of solution blending method was used using ultrasonic. Dispersion of carbon nanofiber was observed by optical microscope and scanning electron microscope (SEM). UV adsorption and turbidity measured by UV spectrometer was used for the comparison of dispersion of carbon nanofiber.

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Manufacture and Mechanical Properties of Carbon Nanofiber Reinforced Hybrid Composites (탄소나노섬유가 강화된 하이브리드 복합재료의 제조 및 기계적 특성)

  • Chung Sang-Su;Park Ji-Sang;Kim Tae-Wook;Kong Jin-Woo
    • Composites Research
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    • v.18 no.3
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    • pp.1-6
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    • 2005
  • Carbon nanofiber exhibits superior and of ien unique characteristics of mechanical, electrical, chemical and thermal properties. Despite of the excellent properties of carbon nanofiber, the properties of carbon nanofiber filled polymer composites were not increased largely. The reason is that it is still difficult to ensure the uniform dispersion of carbon nanofiber in a polymer matrix. In this study, for improvement of the mechanical properties of composites, carbon nanofiber reinforced hybrid composites was investigated. For the dispersion of carbon nanofiber. solution blending method using ultrasonic was used. Dispersion of carbon nanoifiber was observed by scanning electron microscope (SEH). Mechanical properties were measured by universal testing machine(UTM).

Effect of Enzymatic Hydrolysis of Cellulose Nanofibers on the Properties of Poly (Vinyl Alcohol) Nanocomposite

  • Han, Song-Yi;Park, Chan-Woo;Lee, Seung-Hwan
    • Journal of Forest and Environmental Science
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    • v.33 no.2
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    • pp.154-159
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    • 2017
  • Enzymatic treatment was conducted to hydrolyze pure cellulose nanofiber (PCNF), holocellulose nanofiber (HCNF), and lignocellulose nanofiber (LCNF) for 6, 24 and 72 hours and thus-obtained nanofibers (1, 3, 5, 10 wt%) were used to reinforce polyvinyl alcohol (PVA). Glucose production yield was increased by enzymatic hydrolysis. Tensile strength and elastic modulus of all PVA nanocomposite reinforced three nanofibers were improved by increasing enzymatic hydrolysis time of nanofibers and these values were higher in order of nanocomposite reinforced with PCNF>HCNF>LCNF. Furthermore, tensile properties of nanocomposite with PCNF were increased by nanofiber content. Thermal stability of PVA was improved by adding nanofibers and by increasing nanofiber content.

Construction of a Cell-Adhesive Nanofiber Substratum by Incorporating a Small Molecule

  • Jung, Dongju
    • Biomedical Science Letters
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    • v.19 no.1
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    • pp.25-31
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    • 2013
  • Electrospun nanofibers are being widely used as a substratum for mammalian cell culture owing to their structural similarity to collagen fibers found in extracellular matrices of mammalian cells and tissues. Especially, development of diverse synthetic polymers has expanded use of electrospun nanofibers for constructing cell culture substrata. Synthetic polymers have several benefits comparing to natural polymer for their structural consistency, low cost, and capability for blending with other polymers or small molecules to enhance their structural integrity or add biological functions. PMGI (polymethylglutarimide) is one of the synthetic polymers that produced a rigid nanofiber that enables incorporation of small molecules, peptides, and gold nanoparticles through co-electrospinning process, during which the materials are fixed without any chemical modifications in the PMGI nanofibers by maintaining their activities. Using the phenomenon of PMGI nanofiber, here I introduce a construction method of a nanofiber substratum having cell-affinity function towards a pluripotent stem cell by incorporating a small molecule in the PMGI nanofiber.

Preparation and Characterization of Carbon Nanofiber Composite Coated Fabric-Heating Elements (탄소나노섬유복합체를 이용한 의류용 직물발열체의 제조 및 특성)

  • Kang, Hyunsuk;Lee, Sunhee
    • Journal of the Korean Society of Clothing and Textiles
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    • v.39 no.2
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    • pp.247-256
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    • 2015
  • This study prepared fabric-heating elements of carbon nanofiber composite to characterize morphologies and electrical properties. Carbon nanofiber composite was prepared with 15wt% PVDF-HFP/acetone solution, and 0, 1, 2, 4, 8, and 16wt% carbon nanofiber. Dispersion of solution was conducted with stirring for a week, sonification for 24 hours, and storage for a month, until coating. Carbon nanofiber composite coated fabrics were prepared by knife-edge coating on nylon fabrics with a thickness of 0.1mm. The morphologies of carbon nanofiber composite coated fabrics were measured by FE-SEM. Surface resistance was determined by KS K0555 and worksurface tester. A heating-pad clamping device connected to a variable AC/DC power supply was used for the electric heating characteristics of the samples and multi-layer fabrics. An infrared camera applied voltages to samples while maintaining a certain distance from fabric surfaces. The results of morphologies indicated that the CNF content increased specifically to the visibility and presence of carbon nanofiber. The surface resistance test results revealed that an increased CNF content improved the performance of coated fabrics. The results of electric heating properties, surface temperatures and current of 16wt% carbon nanofiber composite coated fabrics were $80^{\circ}C$ and 0.35A in the application of a 20V current. Carbon nanofiber composite coated fabrics have excellent electrical characteristics as fabric-heating elements.

Effects of PU/LP Nanofiber Thin Films Composite Produced from Electrospun for Absorption VOCs (전기방사에 의해 제조된 PU/LP 나노섬유 박막 복합재의 VOCs에 대한 흡착 효과)

  • Ge, Jun-Cong;Kim, Min-Soo;Choi, Nag-Jung
    • Journal of the Korean Society of Mechanical Technology
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    • v.19 no.1
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    • pp.12-20
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    • 2017
  • This study describes the effects of polyurethane/loess powder (PU/LP) nanofiber thin films composite produced from electrospun for absorption volatile organic compounds (VOCs) from air. Environmental issue has become a focus with improving people's living quality. The VOCs are one of the factors that affect the environmental safety. So, in order to improve the environment and safety for people, many air cleaning techniques have been investigated. One of the methods is nanofiber filtration technology. In this study, the PU nanofiber thin film has been studied that it has the adsorption of VOCs capacity, and LP nanoparticles (NPs) can be used as an additive to load into PU nanofiber thin film by electrospinning. For studying PU/LP nanofiber thin films's absorption of VOCs capacity, 4 samples (0, 10, 30, and 50 wt% LP with respect to PU) were manufactured, respectively. The results show that PU composite mats containing 30 wt% LP NPs has the highest VOCs absorption capacity, and the adsorption capacity for toluene was the highest compared to benzene and chloroform.