Direct Imaging of Carbon Nanotube Liquid-Crystalline Phase Development in True Solutions

Kleinerman, Olga; Liberman, Lucy; Behabtu, Natnael; Pasquali, Matteo; Cohen, Yachin; Talmon, Yeshayahu

doi:10.1021/acs.langmuir.7b00206

Cited by 25 publications

(30 citation statements)

References 54 publications

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“…Polypropylene grafted by maleic anhydride (PP-g-MA, 1 wt% of MA) was obtained from Kimia Javid Sepahan, Iran. PP with density of 0.9 g/cm 3 from Jam Polypropylene was used as the matrix polymer with a melt flow index of 25 g/10 min (2308C/2.16 kg) and melting temperature of 1708C.…”

Section: Methodsmentioning

confidence: 99%

Evaluation of surface modification impact on PP/MWCNT nanocomposites by rheological and mechanical characterization, assisted with morphological image processing

2018

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PP/MWCNT nanocomposites were prepared using polypropylene and modified carbon nanotubes (CNTs) via melt-extrusion process. Pure PP was compared with maleic anhydride grafted polypropylene, reinforced with 0.5, 1, and 1.5 wt% COOH-modified nanotubes (PPgCNT) and polypropylene/unmodified CNT nanocomposite (PPCNT) in 1 wt% content. Morphological analysis was performed using FTIR and SEM along with MATLAB and easy fit software-assisted image processing. Image processing of SEM monographs for well-distributed CNTs showed a distribution factor (b) close to 0 while b in agglomerated samples was close to 1. Mechanical properties showed that tensile strength and tensile modulus of nanocomposites were higher than pure PP, in contrast the tensile elongation at break was lower. In addition, nanocomposites with modified nanotubes showed higher tensile strength, tensile modulus, and lower elongation at break compare with unmodified CNT/PP nanocomposites. Capillary rheometries resulted that at high strain rate [100-1500 (s 21 )], melting behavior of the samples is similar to the viscoplastic fluids, and Herschel-Bulkley model is the best approach for prediction of the fluid's rheological behaviors. Adding the modified and unmodified CNTs only changed the model's parameters. Oscillating rheometry studies concluded that at 1% strain, molten nanocomposites followed the viscoelastic behavior while in higher shear rates flow behavior is different. According to the oscillatory rheometry results, storage modulus, loss modulus, complex modulus, and complex viscosity of PPgCNTs were higher than PP and PPCNT. It is concluded that by reduction of b, nanocomposites become more viscoplastic (in high shear rates). Finally, statistical analysis confirmed the rheological and mechanical results. POLYM. COMPOS., 00:000-000, 2018.Image Processing. A new model was provided for studying the distribution of nanotubes through nanocomposites, using image processing analysis of the resulted SEM micrographs. This model is obtained from the statistical scatter FIG. 1. SEM images of PP/MWCNTs composites: (a) PPCNT1, (b) PPgCNT0.5, (c) PPgCNT1, and (d) PPgCNT1.5.

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Section: Methodsmentioning

confidence: 99%

Evaluation of surface modification impact on PP/MWCNT nanocomposites by rheological and mechanical characterization, assisted with morphological image processing

2018

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“… 7 , 8 However, a variety of INTs can be synthesized via sol–gel methods using different precursors, particularly ones with Ge substituting for Si, 9 in either a double-walled or single-walled form. 10 , 11 Similarly to solutions of CNT polyelectrolytes, 12 − 14 INTs form liquid crystalline mesophases, which can be reoriented either by electrical or flow fields, 15 , 16 potentially leading to highly aligned fibers. In contrast to CNTs, INT solutions are optically transparent, which greatly aids the use of polarized optical microscopy (POM) in their characterization.…”

Section: Introductionmentioning

confidence: 99%

Continuous Binder-Free Fibers of Pure Imogolite Nanotubes

Moore

Paineau

Launois

et al. 2021

ACS Appl. Mater. Interfaces

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Imogolite nanotubes (INTs) display a range of useful properties and provide an ideal material system to study the assembly of nanomaterials into macroscopic fibers. A method of wet spinning pure, binder-free imogolite fibers has been developed using double-walled germanium imogolite nanotubes. The nanotube aspect ratio can be controlled during the initial synthesis and is critical to the spinning process. Fibers made from short nanotubes (<100 nm) have very low gel strengths, while dopes with longer nanotubes (500–1000 nm) are readily spinnable. The tensile behavior of the resulting imogolite nanotube fibers is strongly influenced by relative humidity (RH), with a modulus of 30 GPa at 10% RH compared to 2.8 GPa at 85% RH, as well as a change in failure mode. This result highlights the importance of inter-nanotube interactions in such assemblies and provides a useful strategy for further exploration. Interestingly, in the absence of a matrix phase, a degree of misorientation appears to improve load transfer between the individual INTs within the porous fiber, likely due to an increase in the number of interparticle contacts. Imogolite nanotubes are an appealing analogue to other nanotube fiber systems, and it is hoped that learnings from this system can also be used to improve carbon nanotube fibers.

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“…Due to the common anisotropic shape CNTs (high aspect ratio, L/D) will usually form the lyotropic nematic LC phase when they are suspended in a liquid medium at sufficiently high concentration. [10][11][12][13][14][15][16][17][18][19][20][21][22] And the lyotropic CNT liquid crystals can also take place under such specic conditions as the action of external elds: magnetic, 23 electric, 24 shear, 25 spinning, 26 or drawing. 27 The formation of LC ordering for CNTs will facilitate an opportunity to develop novel materials and applications.…”

Section: Introductionmentioning

confidence: 99%