Extensional Rheology of Poly(vinylidene fluoride)/N,N-dimethylformamide Solutions
Typical extension flow occurs in electrospinning process of Poly(vinylidene fluoride) (PVDF) solutions such that researchers focus on extensional rheological behaviors of PVDF solutions. The extensional viscosity of PVDF solutions is measured to know the fluidic deformation in extension flows. The s...
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| Format: | Article |
| Language: | English |
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MDPI AG
2023-02-01
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| Series: | Polymers |
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| Online Access: | https://www.mdpi.com/2073-4360/15/5/1119 |
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| author | Lei Xu Mingxiang Ju Wentai Guo Shengrui Yu |
| author_facet | Lei Xu Mingxiang Ju Wentai Guo Shengrui Yu |
| author_sort | Lei Xu |
| collection | DOAJ |
| description | Typical extension flow occurs in electrospinning process of Poly(vinylidene fluoride) (PVDF) solutions such that researchers focus on extensional rheological behaviors of PVDF solutions. The extensional viscosity of PVDF solutions is measured to know the fluidic deformation in extension flows. The solutions are prepared by dissolving PVDF powder into N,N-dimethylformamide (DMF) solvent. A homemade extensional viscometric device is used to produce uniaxial extension flows and the feasibility of the viscometric device is verified by applying the glycerol as a test fluid. Experimental results show that PVDF/DMF solutions are extension shinning as well as shear shinning. The Trouton ratio of thinning PVDF/DMF solution is close to three at very low strain rate and then reaches a peak value until it drops to a small value at high strain rate. Furthermore, an exponential model may be used to fit the measured values of uniaxial extensional viscosity at various extension rates, while traditional power-law model is applicable to steady shear viscosity. For 10~14% PVDF/DMF solution, the zero-extension viscosity by fitting reaches 31.88~157.53 Pa·s and the peak Trouton ratio is 4.17~5.16 at applied extension rate of less than 34 s<sup>−1</sup>. Characteristic relaxation time is <i>λ</i>~100 ms and corresponding critical extension rate is <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mover accent="true"><mi>ε</mi><mo>˙</mo></mover><mi>c</mi></msub></mrow></semantics></math></inline-formula>~5 s<sup>−1</sup>. The extensional viscosity of very dilute PVDF/DMF solution at very high extension rate is beyond the limit of our homemade extensional viscometric device. This case needs a higher sensitive tensile gauge and a higher-accelerated motion mechanism for test. |
| first_indexed | 2024-03-11T07:13:49Z |
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| id | doaj.art-9fb766a7e8904bb7922019b67a1c9e9e |
| institution | Directory Open Access Journal |
| issn | 2073-4360 |
| language | English |
| last_indexed | 2024-03-11T07:13:49Z |
| publishDate | 2023-02-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Polymers |
| spelling | doaj.art-9fb766a7e8904bb7922019b67a1c9e9e2023-11-17T08:26:22ZengMDPI AGPolymers2073-43602023-02-01155111910.3390/polym15051119Extensional Rheology of Poly(vinylidene fluoride)/N,N-dimethylformamide SolutionsLei Xu0Mingxiang Ju1Wentai Guo2Shengrui Yu3School of Mechanical and Electronic Engineering, Jingdezhen Ceramic University, Jingdezhen 333403, ChinaSchool of Mechanical and Electronic Engineering, Jingdezhen Ceramic University, Jingdezhen 333403, ChinaSchool of Mechanical and Electronic Engineering, Jingdezhen Ceramic University, Jingdezhen 333403, ChinaSchool of Mechanical and Electronic Engineering, Jingdezhen Ceramic University, Jingdezhen 333403, ChinaTypical extension flow occurs in electrospinning process of Poly(vinylidene fluoride) (PVDF) solutions such that researchers focus on extensional rheological behaviors of PVDF solutions. The extensional viscosity of PVDF solutions is measured to know the fluidic deformation in extension flows. The solutions are prepared by dissolving PVDF powder into N,N-dimethylformamide (DMF) solvent. A homemade extensional viscometric device is used to produce uniaxial extension flows and the feasibility of the viscometric device is verified by applying the glycerol as a test fluid. Experimental results show that PVDF/DMF solutions are extension shinning as well as shear shinning. The Trouton ratio of thinning PVDF/DMF solution is close to three at very low strain rate and then reaches a peak value until it drops to a small value at high strain rate. Furthermore, an exponential model may be used to fit the measured values of uniaxial extensional viscosity at various extension rates, while traditional power-law model is applicable to steady shear viscosity. For 10~14% PVDF/DMF solution, the zero-extension viscosity by fitting reaches 31.88~157.53 Pa·s and the peak Trouton ratio is 4.17~5.16 at applied extension rate of less than 34 s<sup>−1</sup>. Characteristic relaxation time is <i>λ</i>~100 ms and corresponding critical extension rate is <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mover accent="true"><mi>ε</mi><mo>˙</mo></mover><mi>c</mi></msub></mrow></semantics></math></inline-formula>~5 s<sup>−1</sup>. The extensional viscosity of very dilute PVDF/DMF solution at very high extension rate is beyond the limit of our homemade extensional viscometric device. This case needs a higher sensitive tensile gauge and a higher-accelerated motion mechanism for test.https://www.mdpi.com/2073-4360/15/5/1119Trouton ratioextensional viscosityshear viscosityuniaxial extension |
| spellingShingle | Lei Xu Mingxiang Ju Wentai Guo Shengrui Yu Extensional Rheology of Poly(vinylidene fluoride)/N,N-dimethylformamide Solutions Polymers Trouton ratio extensional viscosity shear viscosity uniaxial extension |
| title | Extensional Rheology of Poly(vinylidene fluoride)/N,N-dimethylformamide Solutions |
| title_full | Extensional Rheology of Poly(vinylidene fluoride)/N,N-dimethylformamide Solutions |
| title_fullStr | Extensional Rheology of Poly(vinylidene fluoride)/N,N-dimethylformamide Solutions |
| title_full_unstemmed | Extensional Rheology of Poly(vinylidene fluoride)/N,N-dimethylformamide Solutions |
| title_short | Extensional Rheology of Poly(vinylidene fluoride)/N,N-dimethylformamide Solutions |
| title_sort | extensional rheology of poly vinylidene fluoride n n dimethylformamide solutions |
| topic | Trouton ratio extensional viscosity shear viscosity uniaxial extension |
| url | https://www.mdpi.com/2073-4360/15/5/1119 |
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