Formation of bimodal crystal textures in polypropylene

P. G. Andersen*, Stephen Howard Carr

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

57 Scopus citations


Electron microscopy, selected area electron diffraction, X-ray diffraction, and dynamic-mechanical testing have been used to study flow-crystallized and hot drawn isotactic polypropylene. As a result of these investigations, it was found that bimodal crystal textures can apparently be formed by at least two different treatments, but the corresponding morphologies are completely different. Flow-induced crystallization was observed to result in a microstructure of lamellae oriented perpendicular to the flow direction, while hot drawing of polypropylene films above a critical temperature produced a morphology of microfibrils lying parallel to the draw direction. Below this critical temperature, drawing produced a fibrillar morphology having only a typical unimodal fibre texture. As a result of information obtained here, a mechanism involving epitaxial deposition of chain segments onto growing lamellae is concluded to be responsible for formation of the bimodal crystal texture in flow-crystallized material.

Original languageEnglish (US)
Pages (from-to)870-886
Number of pages17
JournalJournal of Materials Science
Issue number5
StatePublished - May 1 1975

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering


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