Formation mechanism of shish in the oriented melt (II) - Two different growth mechanisms along and perpendicular to the flow direction

Shinichi Yamazaki, Kaori Watanabe, Kiyoka Okada, Koji Yamada, Katsuharu Tagashira, Akihiko Toda, Masamichi Hikosaka

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)

Abstract

In part 1 of this series of paper, we have solved the formation mechanism of shish from the oriented melt based on the kinetic observation. In this work, we have shown for the first time the molecular mechanism of the growth of shish by kinetic study. We found that there are two different type of the growth of shish against the flow direction. The growth rate along the flow direction (U) is proportional to ΔT, where ΔT is the degree of supercooling. This indicates that U is mainly controlled by the rearrangement process of the chain near the end surface of the shish. On the other hand, the growth rate perpendicular to the flow direction (V) obeyed a well-known equation V∝exp(-B/ΔT), where B is a constant proportional to the free energy necessary for forming a critical secondary nucleus ΔG*. This indicates that V is mainly controlled by the secondary nucleation process on the side surface of shish. Moreover, we also found that there is a critical shear rate γ̇* for the growth of shish. Below γ̇*, U and V approached to zero and the growth rate of spherulite, respectively. From this experimental fact, we proposed that the chain conformation near the interface between the melt and shish, i.e. near the end and side surface of shish is elongated and oriented by the shear flow above γ̇*.

Original languageEnglish
Pages (from-to)1685-1692
Number of pages8
JournalPolymer
Volume46
Issue number5
DOIs
Publication statusPublished - Feb 14 2005

Keywords

  • Growth
  • Shear flow
  • Shish

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Materials Chemistry

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