• Title/Summary/Keyword: Rheological characterization

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Study on Rheological Characterization of Polyacrylonitrile/Dimethyl Sulfoxide Solution with Change of Storage Times and Temperatures (시간 및 온도변화에 따른 폴리아크릴로니트릴/디메틸술폭시드 중합체 용액의 유변학적 특성 연구)

  • Yang, Jae-Yeon;Lee, Byoung-Min;Kuk, Yun-Su;Kim, Byoung-Suhk;Seo, Min-Kang
    • Composites Research
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    • v.32 no.1
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    • pp.71-77
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    • 2019
  • In this study, the structural and rheological characterizations of polyacrylonitrile(PAN)/dimethyl sulfoxide(DMSO) solutions for PAN fiber were investigated according to the change of storage times and temperatures. As a result, PAN/DMSO solutions exhibited a very characteristic rheological behavior with variation of temperature. The solutions showed an increase of complex viscosity and a decrease of loss tangent($tan{\delta}$) as temperature was increased over the temperature range of 40 and $70^{\circ}C$ and it could be seen that the viscosity rapidly increased at low frequency. These results indicated that the gel polymer and denser gel structure were formed due to the intermolecular hydrogen bonding of water in the polymer solution depending on the storage time.

Rheological Characterization of Polypropylene/Layered Silicate Nanocomposites Using Integral Constitutive Equations (적분형 구성방정식을 이용한 폴리프로필렌/층상 실리케이트 나노복합재료의 유변학적 특성 분석)

  • Lee, Seung-Hwan;Youn, Jae-Ryoun
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2005.11a
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    • pp.137-140
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    • 2005
  • Exfoliated nanocomposites of polypropylene/layered silicate were prepared by a melt compounding process using maleic anhydride modified polypropylene (PP-g-MAH) and organoclay. It was found that polypropylene/layered silicate nanocomposites exhibited remarkable reinforcement compared with the pure polypropylene or conventional composite filled with agglomerated organoclay. The polypropylene /layered silicate nanocomposites showed stronger and earlier shear thinning behaviors and outstanding strain hardening behavior than pure polypropylene or other conventional composites in shear and uniaxial elongational flows, respectively. We simulated rheological modeling for the pure polymer matrix and polypropylene/layered silicate nanocomposite in shear and elongational flows using K-BKZ integral constitutive equation. The two types of K-BKZequations have been examined to describe experimental results of shear and uniaxial elongational viscosities of pure polypropylene and polypropylene/layered silicate nanocomposite.

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Objective Measurements of Textural and Rheological Properties of Cheese (치즈 물성의 객관적 측정을 위한 고찰)

  • Lee, Mee-Ryung
    • Journal of Dairy Science and Biotechnology
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    • v.36 no.2
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    • pp.73-80
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    • 2018
  • The textural and rheological properties of cheese are major attributes for the characterization of cheese types, ripening, and consumer preferences. The use of small amplitude oscillatory rheological testing has made it possible for cheese researchers to assess the major properties of cheese, such as melting behavior and storage modulus, without irreversible deformation. In addition, large deformation testing such as textural profile analysis can assess properties such as hardness of cheese. While the sensory properties of cheese are valued by consumers, objective and reliable measurements are paramount for researchers. Ongoing development and refinement of scientific measurement methods of cheese are vital.

Capillary Breakup of Viscoelastic Fluid and its Extensional Rheology (점탄성유체의 Capillary Breakup 가시화 및 신장유변물성 측정)

  • Jeon, Hyun Woo;Choi, Chan Hyuck;Kim, Byung Hoon;Park, Jinsoo
    • Journal of the Korean Society of Visualization
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    • v.19 no.1
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    • pp.81-87
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    • 2021
  • Extensional flow of viscoelastic fluids is widely utilized in various industrial processes such as electrospinning, 3D printing and plastic injection molding. Extensional rheological properties, such as apparent viscosity and relaxation time, play an important role in the design and evaluation of the viscoelastic fluid-involved processes. In this work, we propose a lab-built capillary breakup extensional rheometer (CaBER) based on flow image processing to investigate the capillary breakup of polyethylene oxide (PEO) solution and its extensional rheological properties. We found that the apparent extensional viscosity and extensional relaxation time of the PEO solution are independent of the strike time. The proposed CaBER is expected to be applied to characterization of the extensional rheological properties of viscoelastic fluids at low cost with high precision.