Frequency dependence of the complex dielectric constant of sodium carboxymethyl cellulose

Nessim, Refaat I.; Botros, Maged G.; Saad, Gamal R.; Shalaby, Mohamed M.

doi:10.1002/apmc.1993.052040104

Cited by 6 publications

(3 citation statements)

References 10 publications

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“…The high values of MC and HPC can be ascribed to the combined effect of the segmental motion of the main chains via the glucosidic bonds and to the presence of moisture/air bubbles in the film that increases interfacial contributions . Very interestingly, the high ε′ of neat NaCMC indicates that carboxymethylation increases the contribution of the orientational polarization due to the dipole moment of −CH 2 OCH 2 COONa over the −CH 2 OH group, although the main contribution of this strong increase is associated to the increased conductivity, as indicated by the high dielectric losses.…”

Section: Resultsmentioning

confidence: 99%

Water-Soluble Cellulose Derivatives as Suitable Matrices for Multifunctional Materials

2019

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This work reports on a simple and environmentally benign route to prepare freestanding magnetic films based on cellulose derivatives through the combination of cobalt ferrite (CoFe 2 O 4 ) nanoparticles with methyl cellulose (MC), hydroxypropyl cellulose (HPC), and sodium carboxymethyl cellulose (NaCMC). Nanoparticles are able to "shield" hydrogen bonding interactions between polysaccharide chains and lower the viscosity of water-dissolved MC, HPC, and NaCMC, allowing an easy film fabrication. Crack-free films with homogeneously dispersed nanoparticles having concentrations up to 50 wt % are fabricated by mechanical agitation followed by doctor blade casting. All of the nanocomposite films keep a substantial level of flexibility with elongation at break exceeding 5%. Halpin− Tsai equations serve to provide further insights on the character of matrix− CoFe 2 O 4 interfaces. Magnetization saturation increases almost linearly with cobalt ferrite concentration up to a maximum value of ∼24−27 emu g −1 for nanocomposites containing 50 wt % of nanoparticles. The dielectric response of the films demonstrates a strong dependence on both the functional groups attached to the main cellulose chain and the ferrite nanoparticle content. The renewable character of the hosting matrices, together with the fabrication methods that solely uses water as a solvent, the decrease of the viscosity with the inclusion of fillers, particularly suitable for printable materials, and the resulting magnetic performance provide novel avenues for the replacement of traditional magnetoactive composites based on petroleum-derived polymers and avoiding the use of toxic solvents.

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Section: Resultsmentioning

confidence: 99%

Water-Soluble Cellulose Derivatives as Suitable Matrices for Multifunctional Materials

2019

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“…0.04 eV) as the environmental dielectric constant (3 env ) decreases (e.g. PFO-Bpy and CMC-Na), 31,32 and becomes saturated as the 3 env increases to 5 or greater (e.g. aqueous solvent and DMF).…”

Section: Resultsmentioning

confidence: 99%

Microenvironment effect on the electronic potentials of individual (6,5)single-walled carbon nanotubes

et al. 2014

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As one of the most fundamental properties of carbon nanotubes, the electronic states of single-walled carbon nanotubes (SWNTs) have been investigated using different experimental approaches. In this study, we report a large shift in the redox potentials and band gaps of (6,5)SWNTs with a change in the solubilizer as determined by in situ photoluminescence (PL) spectroelectrochemical measurements in both aqueous and organic solvents. This shift is attributed to the change in the microenvironment around the SWNT surfaces due to interactions between the solubilizers, including a fluorene-based copolymer (PFO-Bpy) and carboxymethyl cellulose (CMC-Na), and the SWNTs, and this behaviour was proved by molecular mechanics simulations. A striking difference was also revealed in the states of the p-electrons in the sidewalls of SWNTs solubilized in different polymers, which indicates that altering the solubilizer enables tuning of the electronic states of SWNTs. The results presented are important for understanding the effects of the microenvironment on the redox states of individual (n,m)SWNTs.

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“…However, not only does the humidity influence the segmental dynamics of cellulose but also the charge density related to the degree of carboxymethylation can strongly affect it. This effect was investigated by Nessim et al 30 They investigated the influence of charged groups in the cellulose structure on molecular mobility. The study reports that the dielectric property of cellulose depends not only on the degree of substitution but also on the uniformity of the distribution of the charged groups.…”

Section: Introductionmentioning

confidence: 99%

Effects of the Charge Density of Nanopapers Based on Carboxymethylated Cellulose Nanofibrils Investigated by Complementary Techniques

Elert,

Chen,

Smales

et al. 2024

ACS Omega

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Cellulose nanofibrils (CNFs) with different charge densities were prepared and investigated by a combination of different complementary techniques sensitive to the structure and molecular dynamics of the system. The morphology of the materials was investigated by scanning electron microscopy (SEM) and X-ray scattering (SAXS/WAXS). The latter measurements were quantitatively analyzed yielding to molecular parameters in dependence of the charge density like the diameter of the fibrils, the distance between the fibrils, and the dimension of bundles of nanofibrils, including pores. The influence of water on the properties and the charge density is studied by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and broadband dielectric spectroscopy. The TGA measurements reveal two mass loss processes. The one at lower temperatures was related to the loss of water, and the second process at higher temperatures was related to the chemical decomposition. The resulting char yield could be correlated to the distance between the microfibrils. The DSC investigation for hydrated CNFs revealed three glass transitions due to the cellulose segments surrounded by water molecules in different states. In the second heating scan, only one broad glass transition is observed. The dielectric spectra reveal two relaxation processes. At low temperatures or higher frequencies, the β-relaxation is observed, which is assigned to localized fluctuation of the glycosidic linkage. At higher temperatures and lower frequencies, the α-relaxation takes places. This relaxation is due to cooperative fluctuations in the cellulose segments. Both processes were quantitatively analyzed. The obtained parameters such as the relaxation rates were related to both the morphological data, the charge density, and the content of water for the first time.

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Frequency dependence of the complex dielectric constant of sodium carboxymethyl cellulose

Cited by 6 publications

References 10 publications

Water-Soluble Cellulose Derivatives as Suitable Matrices for Multifunctional Materials

Water-Soluble Cellulose Derivatives as Suitable Matrices for Multifunctional Materials

Microenvironment effect on the electronic potentials of individual (6,5)single-walled carbon nanotubes

Effects of the Charge Density of Nanopapers Based on Carboxymethylated Cellulose Nanofibrils Investigated by Complementary Techniques

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