내열성 아라미드 나노섬유의 제조 및 착색 특성

이명선,남영식,박원호,Lee, Myung Sun,Nam, Young Sik,Park, Won Ho 한국섬유공학회 2014 한국섬유공학회지 Vol.51 No.3

The dyeing of meta-aramids (m-aramids) has conventionally been difficult due to their rigid molecular and dense crystalline structure that results from hydrogen bonding, although various dyeing techniques have been applied in the past to improve their dyeability. In this study, m-aramid nanofibers were fabricated by electrospinning with a 15 wt% m-aramid/DMAc solution, followed by either water or thermal treatment. The thermal stability and crystalline structure of the m-aramid nanofibers were investigated by thermogravimetry (TGA) and X-ray diffractometry (XRD), respectively. The effects of the water and thermal treatments on the dyeability of m-aramid nanofibers containing either pigment or dye were compared based on the K/S value and color difference. The results indicated that the use of dye is preferable to the use of pigment to improve the color depth of m-aramid nanofibers.

The study of efficiency of Al₂O₃ drop coated electrospun meta-aramid nanofibers as separating membrane in lithium-ion secondary batteries

Jeon, K.S.,Nirmala, R.,Navamathavan, R.,Kim, K.J.,Chae, S.H.,Kim, T.W.,Kim, H.Y.,Park, S.J. North-Holland 2014 Materials Letters Vol.132 No.-

This paper presents a relatively simple and low-cost approach to prepare Al<SUB>2</SUB>O<SUB>3</SUB> coated with electrospun meta-aramid nanofibers. These Al<SUB>2</SUB>O<SUB>3</SUB>/meta-aramid composite nanofiber mats can be directly used as separating membrane in rechargeable lithium-ion batteries. The manufacture, characteristics, performance and modifications of these Al<SUB>2</SUB>O<SUB>3</SUB>/meta-aramid composite nanofiber separators are introduced and discussed. In cell test, the capacity efficiency of Al<SUB>2</SUB>O<SUB>3</SUB> coated M-aramid nanofibers separator was much better than that of M-aramid nanofibers. The LiCoO<SUB>2</SUB>/graphite cells assembled with the Al<SUB>2</SUB>O<SUB>3</SUB> ceramic coated M-aramid nanofibers separator exhibited reversibility up to 4.2V with a 232mAh/g discharge capacity. Among numerous battery separators, the thermal shutdown and ceramic based separators are of special importance in enhancing the safety of lithium-ion batteries.

Aligned Aramid Nanofiber-reinforced Nanocomposites for Superb Combination of Stiffness and Damping Properties

이동근,염봉준 한국공업화학회 2022 한국공업화학회 연구논문 초록집 Vol.2022 No.1

Solid polymer electrolyte based on aramid nanofiber/epoxy composites

Fahim Sharia(파힘 샤리아),Wonoh Lee(이원오) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.3

Solvent-assisted heat treatment for enhanced chemical stability and mechanical strength of <i>meta</i>-aramid nanofibers

Chung, Junho,Kwak, Seung-Yeop Elsevier 2018 European polymer journal Vol.107 No.-

<P><B>Abstract</B></P> <P> <I>Meta</I>-aramid exhibits excellent chemical stability and mechanical strength owing to its rigid crystal structure. However, the crystal structure is destroyed when <I>meta</I>-aramid nanofibers (mANFs) are fabricated by electrospinning, which results in nanofibers with poor performance characteristics. Here, we present a facile solvent-assisted heat treatment for the efficient crystallization of mANFs. The optimal volume ratio of the co-solvent solution was determined to be 6:5:100 (DMAc:ethylene glycol:water), and the optimal crystallization temperature 120 °C. The crystallinity of the mANFs obtained under these optimized conditions (mANF-6-120) is higher than the crystallinity of mANFs heat-treated at 300 °C (mANF-HT). As a result, mANF-6-120 exhibits superior chemical stability and mechanical strength compared to mANF-HT. After immersion in DMAc for 48 h, the weight of mANF-6-120 is reduced to 28% of its original weight, whereas the relative remaining weight of mANF-HT is less than 8%. The value of Young’s modulus of mANF-6-120 is 1.7 times higher than that of mANF-HT. The crystallization process developed in this study requires less energy and is less expensive than the conventional high-temperature heat treatment process. The <I>meta</I>-aramid nanofiber mat obtained using the proposed process shows great promise for application to water purification and the treatment of polluted air.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We fabricated <I>meta</I>-aramid nanofibers via electrospinning. </LI> <LI> The as-synthesized <I>meta</I>-aramid nanofibers were treated by solvent-assisted thermal treatment. </LI> <LI> The <I>meta</I>-aramid nanofibers were effectively crystallized by the solvent-assisted thermal treatment at 120 °C. </LI> <LI> The highly crystallized nanofibers exhibited enhanced chemical stability and mechanical strength. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Aramid Nanofibers Reinforced Polyacrylonitrile Nanocomposite Films with High Transparency and High Mechanical Properties

Xue Bai,Yinghui Zhao,Zhenhu Song,Hui Chen,Sihang Zhang,Yonghui Luo,YingChun Gu,Shijian Tu,Guo Yao,Sheng Chen 한국섬유공학회 2022 Fibers and polymers Vol.23 No.3

The preparation of polymer nanocomposites combined with high strength, toughness, and high transparencyremains a challenge. Aramid fibers are often used as fiber-reinforced materials for their superior mechanical and thermalproperties, but the weak interfacial force between aramid fibers and matrix polymer limits the application in compositematerials. In this work, aramid nanofibers were prepared by a two-step process, which included deprotonation and acidhydrothermal treatment to obtain better dispersions in general solvents. The hydrothermal aramid nanofibers (HANFs) wereused as reinforcing materials and blended with polyacrylonitrile (PAN) to prepare polyacrylonitrile/aramid nanofibers (PAN/HANFs) composite films with different mass fractions of HANFs. The morphologies of HANFs and the thermal, optical, andmechanical properties of composite films were investigated. Interestingly, when the mass fraction of aramid nanofibers wasless than 1.0 %, the composite films were synchronously strengthened and toughened. When the mass fraction of HANFswas 0.5 %, the tensile strength and toughness of the PAN/HANFs composite film reached 62.04 MPa and 22.56 MJ/m3,which were 74.23 % and 162.31 % higher than the pure PAN film, respectively. Besides, its average transmittance in thevisible light region remained 76.34 %. This work may offer a novel and facile strategy for high transparent reinforcedpolymer composites, which have potential applications in high strength fiber or optical film.

이미드 결합을 통한 3 차원 아라미드 나노복합재 제조

이국환(Guk Hwan Lee),이원오(Wonoh Lee) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.4

그래핀, 탄소나노튜브, 셀룰로오스 나노섬유와 같은 나노물질들은 기능성 재료들의 이온전도도향상, 기계적 특성 향상, 전기전도도 향상과 같은 역할로 사용된다. 아라미드 섬유는 고강도, 내화학성 및 내열성의 특성을 가지고 있고, 이를 이용하여 제조된 아라미드 나노섬유 또한 동일한 특성을 보인다. 이러한 특성을 통해 아라미드 나노섬유 또한 다양한 기능성 재료를 향상시키는 재료로 사용된다. 하지만 아라미드 나노섬유는 물과 접촉하면 재응집이 일어나 고유의 높은 분산성이 감소하게 되어 다른 재료와 복합재료를 만드는 것이 용이하지 않다. 본 연구에서는 물을 사용하지 않고 아라미드 나노섬유 간 공유결합을 유도하여 안정적인 3 차원 아라미드 나노복합소재를 제조하였다. 고르게 분산된 아라미드 나노섬유 용액은 검붉은색을 띄우고 투과전자현미경(TEM)을 통한 측정에서 지름이 10~20nm 로 관측되었다. 제조된 아라미드 나노섬유 용액에 구연산을 첨가하여, 구연산의 카르복실 그룹과 아라미드 나노섬유의 아민 그룹 간의 아마이드 결합을 생성하여 3 차원 나노구조체를 제작하였다. 주사전자현미경 (SEM)을 통한 내구관찰로 아라미드 나노섬유간에 공유결합이 잘 이루어진 것을 확인하였다. Nanomaterials such as Graphene, carbon nanotubes (CNTs), and cellulose nanofibers (CNFs) are used to improve the strength, ion transport and electrical properties of functional materials. Since aramid fibers, the preliminary stage of aramid nanofibers (ANFs), have high strength as well as superior chemical and heat resistances, ANFs are also expected to inherit excellent properties from the aramid fiber. In addition, three-dimensional (3D) nanostructures have been received great interests in many areas due to their superior stress-transfer capability with possessing large surface area. The conventional 3D nanostructure of ANFs has been synthesized via gelation by adding water. However, this water-based process causes a big problem. Well-dispersed aramid nanofibers produce re-agglomerated. ANFs by protonation, and therefore it is limited to manufacture the 3D nanostructure having individually separated ANFs. In this study, we suggest a new protocol to construct structurally stable the ANF 3D nanostructure by introducing covalent crosslinking instead of using water. The ANFs were made by the decomposition of aramid fibers in dimethyl sulfoxide (DMSO) solution by adding potassium hydroxide. A well-synthesized ANF solution has a dark red color and the diameter of ANFs were around 10~20 nm. By adding imide bonding agents such as citric acid without using water, the ANF 3D nanostructure was successfully formed as an aerogel and its scanning electron microscope (SEM) image confirmed the covalent crosslinking between ANFs.

아라미드 나노섬유로 강화된 탄소섬유 강화 복합재료의 동적 기계적 특성 분석

구민예(MinYe Koo),양철민(Cheol-Min Yang),이교우(GyoWoo Lee) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.12

In this study, CFRPs (carbon fiber reinforced plastic) reinforced with ANFs (aramid nanofibers) were fabricated to investigate the dynamic mechanical analysis (DMA). Also, CFRPs reinforced with MWCNTs (multi-walled carbon nanotubes) were produced to be compared for filler effects in the composites. Those nano filler reinforced CFRPs were made by a hand-ray up method and vacuum bagging process. Through the tan δ of DMA, the damping property was evaluated. CFRPs reinforced with ANFs showed a higher tan δ than the neat CFRP by the effect of boundary sliding (filler-filler) and interfacial sling (filler-matrix). Improving damping property from tan δ results was expected to lead the energy dissipation when the external force was applied.

Preparation of Layered Aramid Nanomembranes by Vacuum Assisted Filtration Using Water and Ethanol as Proton Donors

Kan Cheng,Xinwang Gu,Mao Guo,Mingzhuan Li,Shengjun Lu,Haosen Fan 한국섬유공학회 2022 Fibers and polymers Vol.23 No.7

In this paper, two kinds of proton donors, including water and ethanol, are introduced to prepare aramid nanofibers(ANFs) films. The formation mechanism of ANFs films and the influence of water and ethanol have been investigated. Themain formation mechanism was demonstrated that ANFs could self-assemble into layered structure during the filtrationprocess. The results showed that the ANFs films with water as proton donor had a tensile strength of 186.01 MPa and initialthermal decomposition temperature of 503.89 °C, which was 52.68 % and 11.79 % higher than those of the films preparedwith ethanol as proton donor. Meanwhile, compared with spin coating and layer by layer self-assembly methods, vacuumassisted filtration was proved as an effective method to prepare the functional ANFs nanomembranes with highly regular andlayered structures.

Compressible aerogel electrodes for energy devices prepared by self-assembly of cellulose and aramid nanofibers

이아연,박승희,안성훈 한국공업화학회 2021 한국공업화학회 연구논문 초록집 Vol.2021 No.1