• 제목/요약/키워드: polymer rheology

검색결과 313건 처리시간 0.025초

막대형 고분자의 희석용액의 유변학 -새로운 약식 계산방법의 응용- (Rhelogy of Rodlike Macromolecules in Dilute Solution -Application of a New Closure Approximation)

  • 박오옥
    • 유변학
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    • 제1권1호
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    • pp.29-35
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    • 1989

  • 막대형 고분자 희석용액과 분자론적 운동을 새롭게 개발된 약식 계산방법에 의하여 다루었다. 체계적으로 개발되 새로운 방법은 한쪽 방향성이 있는 경우나 전혀 방향성이 없 는 경우에서 적절한 값을 같도록 유도되었다. 이것을 한쪽방향으로의 연신 흐름에 적용한 결과 알려진 해석해와 잘 일치하였으며 단순 전단흐름에 적용한 결과흐름의 세기가 약할 때 는 좋은 결과를 나타내었으나 흐름의 세기가 강할때는 상당한 차이를 보여주었다.

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Constitutive equation and damping function for entangled polymers

  • Osaki, Kunihiro
    • Korea-Australia Rheology Journal
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    • 제11권4호
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    • pp.287-291
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    • 1999

  • The tube model theory of entangled polymer presumes that the polymer chain holds its equilibrium contour length under certain conditions of flow; at times longer than a certain characteristic time, ${\tau}_k$, in the stress relaxation process following any flow history; in steady flow of rates smaller than ${{\tau}_k}^{-1}$; etc. Rheological phenomena associated with this presumption are discussed.

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Strain hardening behavior of linear polymer melts

  • Hong Joung Sook;Ahn Kyung Hyun;Lee Seung Jong
    • Korea-Australia Rheology Journal
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    • 제16권4호
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    • pp.213-218
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    • 2004

  • Linear high-density polyethylene (PE) was controlled to induce strain-hardening behavior by introducing a small amount of second component with an anisotropic structure. In order to form an anisotropic structure in the PE matrix, the polymer was extruded through a twin-screw extruder, and the structure was controlled by varying the extrusion conditions. Depending on conditions, the second component formed a film, thread and droplet structure. If the second component was kept rigid, the morphology evolution could be delayed and the second component could maintain its film or thread structure without further relaxation. In par­ticular, the second component of the thread structure made a physical network and gave rise to remarkable strain hardening behavior under high extension. This study suggests a new method that induces strain hard­ening behavior by introducing a physically networked second component into the linear polymer melt. This result is anticipated to improve the processibility of linear polymers especially when extensional flow is dominant, and to contribute to our understanding of strain hardening behavior.

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Investigation of pressure-volume-temperature relationship by ultrasonic technique and its application for the quality prediction of injection molded parts

  • Kim Jung Gon;Kim Hyungsu;Kim Han Soo;Lee Jae Wook
    • Korea-Australia Rheology Journal
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    • 제16권4호
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    • pp.163-168
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    • 2004

  • In this study, an ultrasonic technique was employed to obtain pressure-volume-temperature (PVT) rela­tionship of polymer melt by measuring ultrasonic velocities under various temperatures and pressures. The proposed technique was applied to on-line monitoring of injection molding process as an attempt to predict quality of molded parts. From the comparison based on Tait equation, it was confirmed that the PVT behav­ior of a polymer is well described by the variation of ultrasonic velocities measured within the polymer medium. In addition, the changes in part weight and moduli were successfully predicted by combining the data collected from ultrasonic technique and artificial neural network algorithm. The results found from this study suggest that the proposed technique can be effectively utilized to monitor the evolution of solid­ification within the mold by measuring ultrasonic responses of various polymers during injection molding process. Such data are expected to provide a critical basis for the accurate prediction of final performance of molded parts.

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