Polymer/Filler Interactions in Ethylene-Octene Copolymer Nanocomposites

Strategic Insights -

Recent research published in the Polymer journal has investigated the microstructure and rheology of melt-compounded ethylene-octene copolymer (EOC) nanocomposites. The study focused on the use of functionalized matrices and nanosilica particles to enhance polymer/filler interactions. The researchers found that the type of silane grafting agent used and the type of silica particles employed significantly influenced the polymer/filler interactions and, consequently, the rheological properties of the composites. The study demonstrated the importance of strong polymer/filler interactions in achieving improved filler dispersion and stable rheological properties.

Key Takeaways:

  • The functionalization of the EOC matrix via silane grafting resulted in enhanced polymer/filler interactions, leading to improved filler dispersion and stable rheological properties.
  • The type of silane grafting agent used, either monofunctional (vinyltriethylsilane-VTES) or bifunctional (vinyltriethoxysilane VTEOS), significantly impacted the polymer/filler interactions.
  • The presence of polymer/filler interactions was confirmed through bound polymer measurements and TEM micrographs.
  • Rheological properties in the melt state revealed significant differences among the EOC-g-VTES, EOC-g-VTEOS, and oct-SiO2-based composites.
  • Time-sweep experiments showed pronounced time-dependence indicative of a tendency toward aggregation for EOC-g-VTES-based composites, whereas strong polymer/filler interactions between EOC-g-VTEOS and oct-SiO2 resulted in a stable response.
  • Strain-sweep experiments revealed a higher critical strain for the onset of non-linearity for EOC-g-VTEOS-based composites, indicative of stronger adhesion between the fillers and the matrix.
  • DMA measurements showed that more energy is dissipated during the glass transition for composites with enhanced polymer/filler interactions.

Statistics:

  • The study used two different types of silica particles: unmodified (SiO2) and modified with octylsilane (oct-SiO2).
  • The researchers observed a fractal-like composite structure in the TEM micrographs.
  • The composites exhibited significant differences in rheological properties, with pronounced time-dependence in EOC-g-VTES-based composites.
  • The critical strain for the onset of non-linearity was higher for EOC-g-VTEOS-based composites than for EOC-g-VTES-based composites.
  • DMA measurements showed an increase in energy dissipation during the glass transition for composites with enhanced polymer/filler interactions.

Sources:

  • M. Bailly et al. "Effect of polymer/filler interactions on the structure and rheological properties of ethylene-octene copolymer/nanosilica composites." Polymer, 2010;51(23):5506-5515.
  • Queen's University, Dept. of Chemical Engineering, Kingston, ON K7L 3N6, Canada.