Molecular weight change during poly(p-oxybenzoyl) whisker formation

Yasuo Kato, Yuhiko Yamashita, Kunio Kimura, Seiji Endo, Toshihiko Ohta

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Molecular weight changes during poly(p-oxybenzoyl) whisker formation from p-acetoxybenzoic acid in liquid paraffin were studied. Our electron microscope observation suggested that the needle crystals in the very early stage of polymerization consist of stacks of oligomer lamellae. Here, the degree of polymerization of precipitated oligomers was found to be about 8, from analysis of oligomers dissolved in liquid paraffin by HPLC method. Furthermore, transesterification in the interlamellar regions starts as soon as crystals precipitate. The average DP of whiskers obtained within 3 min after crystal precipitation increases from 8 to 48. These crystals show fibrillation by crushing of whiskers in liquid nitrogen or etching in KOH solution. This fact indicates that reorganization into extended chain crystals occurs accompanied by the increase of DP. On the other hand, DP of the eventual whiskers increased by 1860. That is, the average molecular length exceeds 1 μm. The formation of such high molecular weight polymers in the solid state polymerization is caused by the closely packed structure of the end groups.

Original languageEnglish
Pages (from-to)583-589
Number of pages7
JournalKobunshi Ronbunshu
Issue number7
Publication statusPublished - 1990
Externally publishedYes


ASJC Scopus subject areas

  • Polymers and Plastics
  • Environmental Science(all)
  • Materials Science (miscellaneous)
  • Chemical Engineering (miscellaneous)
  • Ceramics and Composites

Cite this

Kato, Y., Yamashita, Y., Kimura, K., Endo, S., & Ohta, T. (1990). Molecular weight change during poly(p-oxybenzoyl) whisker formation. Kobunshi Ronbunshu, 47(7), 583-589.