Effect of Thermal History and Shear on the Viscoelastic Response of iPP Containing an Oxalamide-Based Organic Compound

Karel Wilsens*, Laurence Hawke*, Gijs de Kort, Sarah Saidi, Manta Roy, Nils Leone, Daniel Hermida-Merino, Gerrit Peters, Sanjay Rastogi

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

We report on the role of temperature and shear on the melt behavior of iPP in the presence of the organic compound N1,N1′-(propane-1,3-diyl)bis(N2-hexyloxalamide) (OXA3,6). It is demonstrated that OXA3,6 facilitates a viscosity suppression when it resides in the molten state. The viscosity suppression is attributed to the interaction of iPP chains/subchains with molten OXA3,6 nanoclusters. The exact molecular mechanism has not been identified; nevertheless, a tentative explanation is proposed. The observed viscosity suppression appears similar to that encountered in polymer melts filled with solid nanoparticles, with the difference that the OXA3,6 compound reported in this study facilitates the viscosity suppression in the molten state. Upon cooling, as crystal growth of OXA3,6 progresses, the decrease in viscosity is suppressed. Retrospectively, segmental absorption of iPP chains on the surface of micrometer-sized OXA3,6 crystallites favors the formation of dangling arms, yielding OXA3,6 crystallites decorated with partially absorbed iPP chains. In other words, the resulting OXA3,6 particle morphology resembles that of a hairy particle or a starlike polymer chain. Such hairy particles effectively facilitate a viscosity enhancement, similar to branched polymer chains. This hypothesis and its implications for the shear behavior of iPP are discussed and supported using plate–plate rheometry and slit-flow experiments combined with small-angle X-ray scattering analysis.
Original languageEnglish
Pages (from-to)2789-2802
Number of pages14
JournalMacromolecules
Volume52
Issue number7
DOIs
Publication statusPublished - 9 Apr 2019

Keywords

  • FLOW-INDUCED CRYSTALLIZATION
  • X-RAY-SCATTERING
  • ISOTACTIC POLYPROPYLENE
  • NUCLEATING-AGENTS
  • ENHANCED CRYSTALLIZATION
  • MULTIPHASE CRYSTALLIZATION
  • ELASTIC PROPERTIES
  • STRUCTURAL-CHANGE
  • BRILL TRANSITION
  • PARTICLE-SIZE

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