Mechanical Properties of Silica-coated Multi-walled Carbon Nanotube/Epoxy Composites

Kyunghee Kim(김경희),Yeongseon Kim(김영선),Jeonghoon Nam(남정훈),Sung-Hyeon Baeck(백성현),Dong Wha Park(박동화),Sang Eun Shim(심상은) 한국고분자학회 2016 폴리머 Vol.40 No.1

다중벽 탄소 나노튜브(MWCNTs)/에폭시 복합체의 기계적 강도와 전기 절연성을 증가시키기 위하여, tetraethyl orthosilicate(TEOS)를 전구체로 사용한 1 단계 졸-젤 반응을 통하여 다중벽 탄소 나노튜브(MWCNTs)를 실리카 층으로 코팅하였다. MWCNTs 표면을 화학적으로 개질하지 않고 폴리에틸렌이민을 커플링제로 사용하여 실리카로 균일하게 코팅하였다. 실리카 코팅된 MWCNTs 및 순수한 MWCNTs를 충전제로 사용하여 제조된 복합체의 기계적 특성, 열적 특성, 전기적 성질을 관찰하였다. 에폭시 사슬들은 MWCNTs 표면의 실리카 층에 강하게 속박되어, 실리카 층은 MWCNTs에 전기 절연막을 형성하였다. 결과적으로, 실리카 코팅된 MWCNTs가 충전된 에폭시 복합체의 기계적 물성 및 전기저항이 증가하였다. Multi-walled carbon nanotubes (MWCNTs) were coated with silica layers via a one-step sol-gel process with tetraethyl orthosilicate (TEOS) as a silica precursor to enhance the mechanical strength and electrical resistivity of MWCNTs-filled epoxy composites. The MWCNTs were coated uniformly with silica using polyethyleneimine as a coupling agent without chemical modification of the surface of the MWCNTs. The silica-coated MWCNTs were used as a filler in the epoxy. The epoxy composites filled with the raw and silica-coated MWCNTs were prepared and their properties were examined in terms of mechanical, thermal and electrical properties. The epoxy chains were bound strongly to the silica layer on the surface of the MWCNTs, and the silica layer provided the MWCNTs with electrically insulating barriers. As a result, the silica-coated MWCNTs-filled epoxy composites showed improved mechanical strength and electrical resistivity.

Special Issue Paper : Influence of MWCNTs on Fracture Toughness of MWCNTs/Nickel-Pitch Fiber/Epoxy Composites

( Yoon Ji Yim ),( Soo Jin Park ) 한국복합재료학회 2015 Composites research Vol.28 No.6

The influence of MWCNTs on fracture toughness properties of MWCNTs/Nickel-Pitch Fibers/epoxy composites (MWCNTs/Ni-PFs/epoxy) was investigated according to MWCNTs content. Nickel-Pitch-based carbon fibers (Ni-PFs) were prepared by electroless nickel-plating. The surface properties of Ni-PFs were determined by scanning electron microscopy (SEM) and X-ray photoelectron spectrometry (XPS). The fracture toughness of MWCNTs/Ni-PFs/epoxy was assessed by critical stress intensity factor (KIC) and critical strain energy release rate (GIC). From the results, it was found that the fracture toughness properties of MWCNTs/Ni-PFs/epoxy were enhanced with increasing MWCNTs content, whereas the value decreased above 5 wt.%. MWCNTs content. This was probably considered that the MWCNTs entangled with each other in epoxy due to an excess of MWCNTs.

Dispersity and stability measurements of functionalized multiwalled carbon nanotubes in organic solvents

Yeseul Kim,Soon-Min Kwon,Don-Young Kim,Hun-Sik Kim,Hyoung-Joon Jin 한국물리학회 2009 Current Applied Physics Vol.9 No.2

Multiwalled carbon nanotubes (MWCNTs) have attracted a great deal of attention due to their unique properties. However, due to interstrand van der Waals forces, their poor dispersity in aqueous or organic solvents has limited their practical applications. Chemical modification of their surfaces has been investigated in order to achieve good dispersity of MWCNTs in general and specifically regarding organic solvents. Because organic solvents are more suitable than water for processing various polymers, it is necessary for MWCNTs to be dispersed in organic solvents to allow the synthesis of polymer nanocomposites. To uniformly disperse MWCNTs in common organic solvents without the use of surfactants, acid treatment was carried out to introduce carboxyl groups, followed by alkylation with an alkyl halide to form alkylated MWCNTs. In this study, the effective dispersity of alkylated MWCNTs in acetone, toluene, and chloroform was observed by transmission electron microscopy. The dispersive stability of the MWCNTs over a period of 10 days was also investigated by using a Turbiscan optical analyzer. Multiwalled carbon nanotubes (MWCNTs) have attracted a great deal of attention due to their unique properties. However, due to interstrand van der Waals forces, their poor dispersity in aqueous or organic solvents has limited their practical applications. Chemical modification of their surfaces has been investigated in order to achieve good dispersity of MWCNTs in general and specifically regarding organic solvents. Because organic solvents are more suitable than water for processing various polymers, it is necessary for MWCNTs to be dispersed in organic solvents to allow the synthesis of polymer nanocomposites. To uniformly disperse MWCNTs in common organic solvents without the use of surfactants, acid treatment was carried out to introduce carboxyl groups, followed by alkylation with an alkyl halide to form alkylated MWCNTs. In this study, the effective dispersity of alkylated MWCNTs in acetone, toluene, and chloroform was observed by transmission electron microscopy. The dispersive stability of the MWCNTs over a period of 10 days was also investigated by using a Turbiscan optical analyzer.

In Situ Synthesis of Carbon Nanotubes/Graphene Nanoplateles Hybrid Materials with Excellent Mechanical Performance

Menglei Wang,Kejing Yu,Kun Qian 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.4

A two-step method for the preparation of hybrid materials consisting of multi-walled carbon nanotubes (MWCNTs) attached to graphene nanoplatelets (GNPs) was proposed. Firstly, poly (acryloyl chloride) was grafted in situ onto the surface of MWCNTs. Secondly, the obtained MWCNTs (MWCNTs-PACl) were reacted with acid-treated GNPs to form a nanotube–polymer– graphene hybrid. Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, transmission electron microscopy (TEM) and thermal gravimetric analysis (TGA) were used to investigate the forming of the hybrid materials. FTIR results showed that MWCNTs/PACl and GNPs were successfully bridged by chemical bonds like O–C=O and C–O–C. Raman spectroscopy furthermore revealed that acryloyl chloride can be used to connect the MWCNTs and GNPs due to the defects of MWCNTs, and consequently the defects of the hybrid materials were limited. Meanwhile, TEM observation demonstrated the nanostructure clearly in which the MWCNTs with a polymer layer were attached successfully on the surface of GNPs. And TGA curves reflected that the content of MWCNTs and GNPs was about 46.5% in the hybrid materials. In addition, the tensile tests results showed that MWCNTs/GNPs hybrid materials can improve the mechanical performance of epoxy composites in higher degree, compared with MWCNTs or GNPs particles alone.

Effect of Carbon Nanotube Functionalization on the Structure and Properties of Poly(3-hydroxybutyrate)/MWCNTs Biocomposites Mongyoung

허몽영,윤석일,정민해,박영수,김병주,강민석,Peter J. Holden 한국고분자학회 2014 Macromolecular Research Vol.22 No.7

Multi walled carbon nanotubes (MWCNTs) covalently functionalized with an alkyl chain exhibited a betterdispersion in poly(3-hydroxybutyrate) (PHB) solutions and cast films as compared with acid-treated MWCNTs(MWCNT-COOH) due to the much improved solubility in chloroform. The alkylated MWCNTs more effectivelystrengthened PHB composites than non-alkylated MWCNTs due to their uniform dispersion as well as strongerinteraction of alkylated MWCNTs with the PHB matrix. Both acid-treated and alkylated MWCNTs added to PHBmatrix facilitated crystallization kinetics. However the crystallization kinetics were found to be slower for thealkylated MWCNTs/PHB composites than acid-treated MWCNTs composites. The results may be ascribed to theinhibitory effect on PHB crystallization caused by the steric hindrance of the long alkyl chains attached to MWCNTs.

Regenerated bacterial cellulose/multi-walled carbon nanotubes composite fibers prepared by wet-spinning

Peng Chen,Hun-Sik Kim,윤영수,Hyoung-Joon Jin 한국물리학회 2009 Current Applied Physics Vol.9 No.2

Regenerated bacterial cellulose (BC) and regenerated bacterial cellulose/multi-walled carbon nanotubes (BC/MWCNTs) composite fibers were prepared by wet-spinning of a regenerated BC and BC/MWCNTs solution dissolved in dimethylacetamide/lithium chloride, and coagulated with ethanol. Field emission scanning electron microscopy and transmission electron microscopy showed smooth continuous fibers with well-dispersed MWCNTs. The chemical structure of the specimens was analyzed by Fourier transform infrared spectroscopy. The results obtained by using a universal testing machine indicated that the mechanical properties of the fibers were enhanced considerably by reinforcement with MWCNTs. There was an approximate 430% increase in the modulus of the regenerated BC/MWCNTs composite fibers, compared with the original pristine BC. Moreover, the electrical conductivity of the regenerated BC/MWCNTs (1.0 wt%) composite fibers was 1.7 × 10-10 S/cm. Regenerated bacterial cellulose (BC) and regenerated bacterial cellulose/multi-walled carbon nanotubes (BC/MWCNTs) composite fibers were prepared by wet-spinning of a regenerated BC and BC/MWCNTs solution dissolved in dimethylacetamide/lithium chloride, and coagulated with ethanol. Field emission scanning electron microscopy and transmission electron microscopy showed smooth continuous fibers with well-dispersed MWCNTs. The chemical structure of the specimens was analyzed by Fourier transform infrared spectroscopy. The results obtained by using a universal testing machine indicated that the mechanical properties of the fibers were enhanced considerably by reinforcement with MWCNTs. There was an approximate 430% increase in the modulus of the regenerated BC/MWCNTs composite fibers, compared with the original pristine BC. Moreover, the electrical conductivity of the regenerated BC/MWCNTs (1.0 wt%) composite fibers was 1.7 × 10-10 S/cm.

Fabrication and Performance of Multi-wall Carbon Nanotubes Reinforced Polyimide Electrospun Nanofiber Membranes

Shenbing Cao,Taohai Yan 한국섬유공학회 2023 Fibers and polymers Vol.24 No.11

Polyimide (PI) nanofiber membranes (NFMs) via electrospinning demonstrate widespread applications with an intrinsic drawback of lower mechanical performance, which could be improved with multi-wall carbon nanotubes (MWCNTs). PI NFMs was fabricated via a simple thermal induced imidization of polyamic acid (PAA) NFMs and MWCNTs/PI composite NFMs were also investigated on the effect of MWCNTs on morphology, mechanical performance, and its possible carbonization. Such simply thermal induced imidization of PAA demonstrates successfully to be PI, and small amounts of MWCNTs could reduce the diameter and distribution of MWCNTs/PI nanofibers, and coarse and granular-like surface appeared on MWCNTs/PI composite nanofibers as the MWCNTs was increased up to 1.0 wt.%. Notably, addition of MWCNTs improved thermal stability and mechanical performance of MWCNTs/PI composite NFMs, but it lowered the mechanical performance of such composite NFMs at higher carbonization temperatures, which makes its carbonized NFMs even more inclined to be fragile and fracture.

In-situ synthesized ZnFe₂O₄ firmly anchored to the surface of MWCNTs as a long-life anode material with high lithium storage performance

Yang, Tianbo,Zhang, Wanxi,Li, Linlin,Jin, Bo,Jin, Enmei,Jeong, Sangmoon,Jiang, Qing Elsevier 2017 APPLIED SURFACE SCIENCE - Vol.425 No.-

<P><B>Abstract</B></P> <P>Because of two different metal cations in the crystal structures, binary transition metal oxides possess a lot of unique properties. ZnFe<SUB>2</SUB>O<SUB>4</SUB> emerges from these transition metal oxides on account of its high theoretical capacity (1072mAhg<SUP>−1</SUP>). One-dimensional multi-walled carbon nanotubes (MWCNTs) would be a desirable conductive additive for ZnFe<SUB>2</SUB>O<SUB>4</SUB>, thereby improving the electrochemical performance of ZnFe<SUB>2</SUB>O<SUB>4</SUB>. In this work, we prepare ZnFe<SUB>2</SUB>O<SUB>4</SUB>/MWCNTs by solvothermal method with further heat-treatment. ZnFe<SUB>2</SUB>O<SUB>4</SUB> nanoparticles are firmly anchored to the surface of MWCNTs. ZnFe<SUB>2</SUB>O<SUB>4</SUB>/MWCNTs nanocomposite displays high specific capacity (1278mAhg<SUP>−1</SUP> at a current density of 200mAg<SUP>−1</SUP> after 200 cycles, and 565mAhg<SUP>−1</SUP> at a current density of 1500mAg<SUP>−1</SUP> after 500 cycles), and good rate performance (367mAhg<SUP>−1</SUP> even at a current density of 6000mAhg<SUP>−1</SUP> after 80 cycles). The superior electrochemical performance may promote ZnFe<SUB>2</SUB>O<SUB>4</SUB> to be a promising alternative anode in lithium-ion batteries.</P> <P><B>Highlights</B></P> <P> <UL> <LI> ZnFe<SUB>2</SUB>O<SUB>4</SUB> nanoparticles and ZnFe<SUB>2</SUB>O<SUB>4</SUB>/MWCNTs composites have been prepared by a facile solvothermal method. </LI> <LI> ZnFe<SUB>2</SUB>O<SUB>4</SUB> nanoparticles are firmly anchored to the surface of MWCNTs. MWCNTs can suppress the growth of ZnFe<SUB>2</SUB>O<SUB>4</SUB> nanoparticles. </LI> <LI> ZnFe<SUB>2</SUB>O<SUB>4</SUB>/MWCNTs nanocomposite displays high specific capacity at a high current density. </LI> </UL> </P>

A study of the Characterization and Synthesis of MWCNTs under a Magnetic Field via an Arc Discharge Technique

Sahar Tabrizi,Nafiseh Moghimi,Amir Hassanjani-Roshan,Alireza Hojabri 한양대학교 세라믹연구소 2013 Journal of Ceramic Processing Research Vol.14 No.4

Multi-walled carbon nanotubes (MWCNTs) were synthesized by arc discharge in a magnetic field and a low pressure helium gas using mixtures of FeS/Co, FeS/Ni and FeS/Co/Ni catalysts. The synthesized carbon materials indicated a high-purity of MWCNTs related to decreasing the metal catalysts results from applying the magnetic field which was investigated by X-ray diffraction (XRD) analysis and a high-yield of MWCNTs with less amorphous carbon in the presence of the magnetic field for all mixtures as shown by scanning electron microscopy (SEM). Raman spectroscopy was used to characterize the MWCNTs. The ratio of intensity of the graphitic mode to the defect mode (IG/ID) showed that the quality and crystallity of MWCNTs, which were synthesized using FeS/Ni and FeS/Co/Ni decreased in the presence of magnetic field while the quality of MWCNTs, synthesized using FeS/Co increased. Thermo gravimetric analysis (TG/DTA) was performed for quantitative MWCNTs purity assessment. Results showed that the purity of MWCNTs was increased for all cases in the presence of a magnetic field. This was attributed to the concentration of carbon monomers in the arc plasma with the magnetic field.

Mechanical properties of epoxy composites reinforced with fluorinated MWCNTs and graphene nanoplatelets

이경민,이시은,이영석 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.0

Multi-walled carbon nanotubes (MWCNTs) and graphene nanoplatelets (GNP) are treated by direct fluorination and the effects of fluorination on surface of MWCNTs and GNP are investigated by x-ray photo electron spectroscopy (XPS). The different properties of modified MWCNTs/ GNP/epoxy composites are obtained by tensile test, impact test, and scanning electron microscopy (SEM). The mechanical properties of the composites including modified MWCNTs and GNP were observed in tensile strength of 38.3 MPa, which are indicated maximum increase with approximately 88.7% than that of neat epoxy. In addition, the composites also show the best result of impact strength compared to the others. As a result, the fluorination treatment in MWCNTs and GNP provides with an improved dispersion of modified MWCNTs and GNP in epoxy matrix and reinforcement of properties in epoxy composites.