Effect of dynamic vulcanization on co-continuous morphology

  1. (PDF, 385 KB)
  2. Get@NRC: Effect of dynamic vulcanization on co-continuous morphology (Opens in a new window)
DOIResolve DOI: http://doi.org/10.1002/aic.10946
AuthorSearch for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for:
Journal titleAIChE Journal
Pages34113420; # of pages: 10
SubjectPolymer blends; co-continuous morphology; dynamic vulcanization; thermo-plastic vulcanizates; FIB/TMAFM
AbstractThis study examines the effect of dynamic vulcanization on the co-continuous morphology in ethylene-propylene-diene terpolymer (EPDM)/polypropylene (PP) blends using a technique of morphology investigation involving focused ion beam (FIB) etching of the sample surface, followed by topological investigation of the sample surface using tapping mode atomic force microscopy (TMAFM). The FIB ion etching rates of EPDM and PP are distinctly different, and these differences create a significant topological contrast between the phases when subsequently analyzed by atomic force microscopy. This approach allows for the high-resolution observation of dispersed EPDM, and phases as small as 100 nm, are clearly identified. Since it is shown that the etching rates of noncrosslinked and crosslinked EPDM are similar, it was necessary to selectively remove the noncrosslinked EPDM phase by solvent dissolution. This combination of techniques then allows for the clear distinction of polypropylene, as well as noncrosslinked and crosslinked EPDM phases in the blend. The high-resolution micrographs together with the continuity data, surprisingly, indicate that a noncrosslinked co-continuous EPDM phase (α-network) transits to a finer network of crosslinked EPDM (β-network) after dynamic crosslinking. It is suggested that this β-network is produced as a result of the viscosity mismatch between the noncrosslinked and crosslinked EPDM melt occurring at the outer envelope of the α-network during dynamic crosslinking. As the crosslinked material pulls away from the noncrosslinked material under dynamic melt mixing conditions, it creates a smearing effect. It is shown that the initial α-network maintains its continuity and demonstrates a diminished pore diameter as crosslinking proceeds. Furthermore, when the noncrosslinked material is extracted almost no crosslinked phase (<1%) is found to be present in the extract. These results strongly indicate that the crosslinking proceeds initially at the outer envelope of the EPDM phase, and works its way toward the center.
Publication date
AffiliationNational Research Council Canada (NRC-CNRC); NRC Industrial Materials Institute
Peer reviewedYes
NRC number53739
NPARC number15905575
Export citationExport as RIS
Report a correctionReport a correction
Record identifier6007c684-3c55-45cc-a47b-d2531fb23caf
Record created2010-08-17
Record modified2016-05-09
Bookmark and share
  • Share this page with Facebook (Opens in a new window)
  • Share this page with Twitter (Opens in a new window)
  • Share this page with Google+ (Opens in a new window)
  • Share this page with Delicious (Opens in a new window)