Rigid Rod-like Viscoelastic Behaviors of Methyl Cellulose Samples with a Wide Range of Molar Masses Dissolved in Aqueous Solutions
The viscoelastic behaviors of aqueous solutions of commercially available methyl cellulose (MC) samples with a degree of substitution of 1.8 and a wide range of weight average molar masses (<i>M</i><sub>w</sub>) were investigated over a wide concentration (<i>c</i>...
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MDPI AG
2024-01-01
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| Series: | Molecules |
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| Online Access: | https://www.mdpi.com/1420-3049/29/2/466 |
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| author | Daiki Nakagawa Erika Saiki Yoshiki Horikawa Toshiyuki Shikata |
| author_facet | Daiki Nakagawa Erika Saiki Yoshiki Horikawa Toshiyuki Shikata |
| author_sort | Daiki Nakagawa |
| collection | DOAJ |
| description | The viscoelastic behaviors of aqueous solutions of commercially available methyl cellulose (MC) samples with a degree of substitution of 1.8 and a wide range of weight average molar masses (<i>M</i><sub>w</sub>) were investigated over a wide concentration (<i>c</i>) range at some temperatures from −10 to 25 °C. The viscoelastic parameters useful to discuss the structure and dynamics of MC-forming particles in aqueous solutions were precisely determined, such as the zero-shear viscosity (<i>η</i><sub>0</sub>), the steady-state compliance (<i>J</i><sub>e</sub>), the average relaxation time (<i>τ</i><sub>w</sub>), and the activation energy (<i>E</i>*) of <i>τ</i><sub>w</sub>. Because previously obtained scattering and intrinsic viscosity ([<i>η</i>]) data revealed that the MC samples possess a rigid rod-like structure in dilute aqueous solutions over the entire <i>M</i><sub>w</sub> range examined, the viscoelastic data obtained in this study were discussed in detail based on the concept of rigid rod particle suspension rheology. The obtained <i>J</i><sub>e</sub><sup>−1</sup> was proportional to the number density of sample molecules (ν = <i>cN</i><sub>A</sub><i>M</i><sub>w</sub><sup>−1</sup>, where <i>N</i><sub>A</sub> means the Avogadro’s constant) over the <i>ν</i> range examined irrespective of <i>M</i><sub>w</sub>. The reduced relaxation time (4<i>N</i><sub>A</sub><i>τ</i><sub>w</sub>(3<i>νJ</i><sub>e</sub> [<i>η</i>]<i>η</i><sub>m</sub><i>M</i><sub>w</sub>)<sup>−1</sup>), where <i>η</i><sub>m</sub> means the medium viscosity, was proportional to (<i>νL</i><sup>3</sup>)<sup>2</sup>, <i>L</i>; the average particle length depending on <i>M</i><sub>w</sub> for each sample was determined in a previous study; and the reduced specific viscosity (<i>η</i><sub>sp</sub><i>N</i><sub>A</sub><i>L</i><sup>3</sup>(<i>M</i><sub>w</sub> [<i>η</i>])<sup>−1</sup>), where <i>η</i><sub>sp</sub> means the specific viscosity, was proportional to (<i>νL</i><sup>3</sup>)<sup>3</sup> in a range of <i>νL</i><sup>3</sup> < 3 × 10<sup>2</sup>. These findings were typical characteristics of the rigid rod suspension rheology. Therefore, the MC samples behave as entangling rigid rod particles in the <i>νL</i><sup>3</sup> range from rheological points of view. A stepwise increase in <i>E</i>* was clearly observed in a <i>c</i> range higher than the [<i>η</i>]<sup>−1</sup> value irrespective of <i>M</i><sub>w</sub>. This observation proposes that contact or entanglement formation between particles formed by MC molecules results in an increase in <i>E</i>*. |
| first_indexed | 2024-03-08T09:48:45Z |
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| institution | Directory Open Access Journal |
| issn | 1420-3049 |
| language | English |
| last_indexed | 2024-03-08T09:48:45Z |
| publishDate | 2024-01-01 |
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| series | Molecules |
| spelling | doaj.art-6c1d645dbb824d5aa0c91bc91f3fd35a2024-01-29T14:08:51ZengMDPI AGMolecules1420-30492024-01-0129246610.3390/molecules29020466Rigid Rod-like Viscoelastic Behaviors of Methyl Cellulose Samples with a Wide Range of Molar Masses Dissolved in Aqueous SolutionsDaiki Nakagawa0Erika Saiki1Yoshiki Horikawa2Toshiyuki Shikata3Cellulose Research Unit, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, JapanCellulose Research Unit, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, JapanCellulose Research Unit, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, JapanCellulose Research Unit, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, JapanThe viscoelastic behaviors of aqueous solutions of commercially available methyl cellulose (MC) samples with a degree of substitution of 1.8 and a wide range of weight average molar masses (<i>M</i><sub>w</sub>) were investigated over a wide concentration (<i>c</i>) range at some temperatures from −10 to 25 °C. The viscoelastic parameters useful to discuss the structure and dynamics of MC-forming particles in aqueous solutions were precisely determined, such as the zero-shear viscosity (<i>η</i><sub>0</sub>), the steady-state compliance (<i>J</i><sub>e</sub>), the average relaxation time (<i>τ</i><sub>w</sub>), and the activation energy (<i>E</i>*) of <i>τ</i><sub>w</sub>. Because previously obtained scattering and intrinsic viscosity ([<i>η</i>]) data revealed that the MC samples possess a rigid rod-like structure in dilute aqueous solutions over the entire <i>M</i><sub>w</sub> range examined, the viscoelastic data obtained in this study were discussed in detail based on the concept of rigid rod particle suspension rheology. The obtained <i>J</i><sub>e</sub><sup>−1</sup> was proportional to the number density of sample molecules (ν = <i>cN</i><sub>A</sub><i>M</i><sub>w</sub><sup>−1</sup>, where <i>N</i><sub>A</sub> means the Avogadro’s constant) over the <i>ν</i> range examined irrespective of <i>M</i><sub>w</sub>. The reduced relaxation time (4<i>N</i><sub>A</sub><i>τ</i><sub>w</sub>(3<i>νJ</i><sub>e</sub> [<i>η</i>]<i>η</i><sub>m</sub><i>M</i><sub>w</sub>)<sup>−1</sup>), where <i>η</i><sub>m</sub> means the medium viscosity, was proportional to (<i>νL</i><sup>3</sup>)<sup>2</sup>, <i>L</i>; the average particle length depending on <i>M</i><sub>w</sub> for each sample was determined in a previous study; and the reduced specific viscosity (<i>η</i><sub>sp</sub><i>N</i><sub>A</sub><i>L</i><sup>3</sup>(<i>M</i><sub>w</sub> [<i>η</i>])<sup>−1</sup>), where <i>η</i><sub>sp</sub> means the specific viscosity, was proportional to (<i>νL</i><sup>3</sup>)<sup>3</sup> in a range of <i>νL</i><sup>3</sup> < 3 × 10<sup>2</sup>. These findings were typical characteristics of the rigid rod suspension rheology. Therefore, the MC samples behave as entangling rigid rod particles in the <i>νL</i><sup>3</sup> range from rheological points of view. A stepwise increase in <i>E</i>* was clearly observed in a <i>c</i> range higher than the [<i>η</i>]<sup>−1</sup> value irrespective of <i>M</i><sub>w</sub>. This observation proposes that contact or entanglement formation between particles formed by MC molecules results in an increase in <i>E</i>*.https://www.mdpi.com/1420-3049/29/2/466methyl celluloseviscoelastic behaviorrheologyzero-shear viscositysteady-state complianceaverage relaxation time |
| spellingShingle | Daiki Nakagawa Erika Saiki Yoshiki Horikawa Toshiyuki Shikata Rigid Rod-like Viscoelastic Behaviors of Methyl Cellulose Samples with a Wide Range of Molar Masses Dissolved in Aqueous Solutions Molecules methyl cellulose viscoelastic behavior rheology zero-shear viscosity steady-state compliance average relaxation time |
| title | Rigid Rod-like Viscoelastic Behaviors of Methyl Cellulose Samples with a Wide Range of Molar Masses Dissolved in Aqueous Solutions |
| title_full | Rigid Rod-like Viscoelastic Behaviors of Methyl Cellulose Samples with a Wide Range of Molar Masses Dissolved in Aqueous Solutions |
| title_fullStr | Rigid Rod-like Viscoelastic Behaviors of Methyl Cellulose Samples with a Wide Range of Molar Masses Dissolved in Aqueous Solutions |
| title_full_unstemmed | Rigid Rod-like Viscoelastic Behaviors of Methyl Cellulose Samples with a Wide Range of Molar Masses Dissolved in Aqueous Solutions |
| title_short | Rigid Rod-like Viscoelastic Behaviors of Methyl Cellulose Samples with a Wide Range of Molar Masses Dissolved in Aqueous Solutions |
| title_sort | rigid rod like viscoelastic behaviors of methyl cellulose samples with a wide range of molar masses dissolved in aqueous solutions |
| topic | methyl cellulose viscoelastic behavior rheology zero-shear viscosity steady-state compliance average relaxation time |
| url | https://www.mdpi.com/1420-3049/29/2/466 |
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