The kinetics and morphology of polyethylene solution crystallization

A. J. McHugh*, W. R. Burghardt, D. A. Holland

*Corresponding author for this work

Research output: Contribution to journalArticle

11 Scopus citations

Abstract

An experimental study has been carried out on the crystallization kinetics and morphology of two high molecular weight polyethylene fractions in 0.1 wt% xylene solutions. Transformation data for the kinetics were taken dilatometrically over a range of temperatures, and Avrami plots for the higher molecular weight fraction ( M ̄w = 3 × 106) show a change in slope from n = 3 at low undercoolings to n = 4 at higher undercoolings. Slopes of 4 resulted for the lower molecular weight fraction (3.8 × 105) over the entire temperature range studied. Analysis of the crystals by optical and electron microscopy and hot stage demonstrated that the growth morphology is three-dimensional and remains the same for both fractions over the temperature ranges used in the dilatometric experiments. Analysis of the transformation data in terms of both the Avrami equation and molecular nucleation and growth models demonstrated that nucleation is heterogeneous, varying between instantaneous and sporadic depending on the molecular weight and undercooling, and adequately described in the latter cases by either three dimensional or monolayer heterogeneous formation. Values for the end surface energies could be conveniently analysed in terms of the Hoffman-type regimes for chain folded crystallization and the discussion suggests that nucleation may be resulting from regions of entangled clusters of the macromolecules.

Original languageEnglish (US)
Pages (from-to)1585-1594
Number of pages10
JournalPolymer
Volume27
Issue number10
DOIs
StatePublished - Oct 1986

Keywords

  • Avrami constants
  • crystallization
  • dilatometry
  • growth morphology
  • heterogeneous nucleation
  • polyethylene
  • solutions

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Materials Chemistry

Fingerprint Dive into the research topics of 'The kinetics and morphology of polyethylene solution crystallization'. Together they form a unique fingerprint.

  • Cite this