• 제목/요약/키워드: rheology

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Rheological properties and crystallization kinetics of polypropylene block copolymer with repeated extrusion

  • Sung Yu-taek;Seo Won Jin;Kim Jong Sung;Kim Woo Nyon;Kwak Dong-Hwan;Hwang Tae-Won
    • Korea-Australia Rheology Journal
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    • 제17권1호
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    • pp.21-25
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    • 2005
  • Rheological properties and crystallization kinetics of the polypropylene (PP) block copolymer and recycled PP block copolymer were studied by advanced rheometric expansion system (ARES), differential scanning calorimetry (DSC), and optical microscopy. In the study of the dynamic rheology, it is observed that the storage modulus and loss modulus for the PP block copolymer and recycled PP block copolymer did not change with frequency. In the study of the effect of the repeated extrusion on the crystallization rate, half crystallization time of the PP samples was increased with the number of repeated extrusion in isothermal crystallization temperature ($T_c$). From the isothermal crystallization kinetics study, the crystallization rate was decreased with the increase of the number of repeated extrusion. Also, from the result of Avrami plot, the overall crystallization rate constant (K) was decreased with the increase of the number of the repeated extrusion. From the study of the optical microscopy, the size of the spherulite of the PP samples did not change significantly with the number of repeated extrusion. However, it was clearly observed that the number of the spherulite growth sites was decreased with the number of repeated extrusion. From the results of the crystallization rate, isothermal crystallization kinetics, Avrami plots, and optical microscopy, it is suggested that the crystallization rate of the PP block copolymer is decreased with the increase of the number of repeated extrusion.

Lessons from history

  • Walters, K.
    • Korea-Australia Rheology Journal
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    • 제11권4호
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    • pp.265-268
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    • 1999
  • The main events in the historical development of Rheology are traced and particular attention is paid to the leading players, the controversies, the priority disputes and the nomenclature disagreements. Some of the lessons to be learned from the past are then highlighted and a positive assessment is given of the prospects for rheological research in the next millennium

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Modelling nonlinear polymer rheology is still challenging

  • Marrucci Giuseppe;Ianniruberto Giovanni
    • Korea-Australia Rheology Journal
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    • 제17권3호
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    • pp.111-116
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    • 2005
  • The new tube model with variable diameter (Marrucci and Ianniruberto, 2004), recently introduced to interpret new elongational data of polymer melts, is here extended to encompass arbitrary flows, specifically shear flows. The predicted results compare well with existing data of entangled polymer melts. Challenges still remain when the comparison is extended to recent elongational data on entangled solutions by Sridhar.