Rheological behavior of cycloolefin copolymer/graphite composites

Kasgoz A., Akin D., Durmus A.

POLYMER ENGINEERING AND SCIENCE, vol.52, no.12, pp.2645-2653, 2012 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 52 Issue: 12
  • Publication Date: 2012
  • Doi Number: 10.1002/pen.23221
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.2645-2653
  • Istanbul University Affiliated: Yes


In this study, morphological and rheological properties of cycloolefin copolymer (COC)/graphite composites prepared in a twin screw extruder by using various amounts of graphite (G) and expanded graphite (EG) were investigated in detail. Rheological behaviors of the samples were measured in a dynamic oscillatory rheometer in the melt state. Rheology data were analyzed in different ways in order to quantify the microstructural features which indicate the solid-state physical properties of the composite materials. In the linear viscoelastic region, increasing of storage modulus (G') with the filler amount and the van Gurp-Palmen plots were used to determine the percolation threshold which is the critical filler amount for the physical network formation by the G sheets. Percolation threshold values were found to be about 21.5 phr and 3.8 phr for the G- and EG-loaded samples, respectively. Microstructures of the samples which include quite higher amount of filler than the percolation were observed in a scanning electron microscopy. It was found that the sheets of pristine G maintained their original stack form while the EG was successfully dispersed in the COC phase and formed three dimensional house-of-card structures without a compatibilizer. POLYM. ENG. SCI., 52:2645-2653, 2012. (C) 2012 Society of Plastics Engineers