Characterization of polyethylene with partially random chlorine substitution

C. H. Stephens, H. Yang, M. Islam, S. P. Chum, S. J. Rowan, A. Hiltner, E. Baer

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)

Abstract

A series of chlorine-containing polymers were prepared by ring-opening metathesis polymerization (ROMP) followed by hydrogenation. This synthesis route was chosen specifically so that chain microstructures would be obtained that resembled copolymers of ethylene and vinyl chloride. The chlorine content was varied by the copolymerization of 5-chlorocyclooctene and cyclooctene. Differential scanning calorimetry, light microscopy, tapping-mode atomic force microscopy, wide-angle X-ray diffraction (WAXD), and density were employed to characterize the polymers. The copolymers had certain restrictions on the length of the methylene sequence between substituted carbons, however, ROMP copolymerization introduced enough variation in the methylene sequence length that model copolymers with the equivalent of 14 mol % vinyl chloride or less closely resembled random copolymers of ethylene and vinyl chloride. These materials organized as spherulites and exhibited the orthorhombic crystal form. Constraints on the placement of chlorine atoms strongly affected the crystallization of polymers with more than the equivalent of 14 mol % vinyl chloride. More regular chlorine substitution along the polyethylene chain translated into better ordered crystal structures with sharp melting peaks. The granular morphology of these materials at ambient temperature was interpreted as fringed micellar crystals. The WAXD patterns provided definitive evidence that chains in the fringed micelle took the hexagonal crystal form. The lower density hexagonal form facilitated the crystallization of short ethylene sequences and accommodated chlorine atoms more easily than the orthorhombic form.

Original languageEnglish
Pages (from-to)2062-2070
Number of pages9
JournalJournal of Polymer Science, Part B: Polymer Physics
Volume41
Issue number17
DOIs
Publication statusPublished - 2003 Sep 1
Externally publishedYes

Keywords

  • Chlorinated polyethylene
  • Ethylene copolymers
  • Poly(vinyl chloride) (PVC)
  • Polyethylene (PE)
  • ROMP

ASJC Scopus subject areas

  • Polymers and Plastics
  • Materials Chemistry

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