Reduced percolation concentration in polypropylene/expanded graphite composites: Effect of viscosity and polypyrrole
Publikation: Beitrag in Fachzeitschrift › Forschungsartikel › Beigetragen › Begutachtung
Beitragende
Abstract
With the goal to obtain material combining electrical and thermal conductivity at low filler loadings, composites based on polypropylenes (PP) and expanded graphite (EG) have been prepared. The effects of matrix viscosity and of coating the EG particles with polypyrrole (PPy, EG/PPy=37.5/62.5 by weight) on the EG dispersibility and formation of percolation structures have been analyzed. When increasing the EG amount from 6 to 8 wt %, the electrical conductivity of PP/EG composites increased by 7-9 orders of magnitude, independent of matrix viscosity. When EG-PPy is added, percolation was observed between 8 and 12 wt % EG-PPy (3 and 4.5 wt % EG) in case of PP with higher viscosity and 6 wt % EG (2.25 wt % EG) in case of PP with lower viscosity, exhibiting a strong synergistic effect of EG and PPy in the latter case. In contrast, PPy does not contribute to reduction of thermal percolation concentration. Thermal percolation is observed at 8 wt % EG in PP/EG composites, but no percolation was found in PP/EG-PPy composites with EG-PPy contents of up to 20 wt %, corresponding to 7.5 wt % EG. Analyzing the melt rheology it becomes clear that the contribution of PPy to the formation of a filler network is strongly dependent on the matrix viscosity. The comparison of thermal, electrical and rheological percolation reveals that PPy participates in electron transport reducing the electrical percolation but not to heat transport. Overall, we found a good correlation between electrical, thermal, and melt rheological percolation concentrations. (c) 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41994.
Details
Originalsprache | Englisch |
---|---|
Seitenumfang | 12 |
Fachzeitschrift | Journal of applied polymer science |
Jahrgang | 132 |
Ausgabenummer | 20 |
Publikationsstatus | Veröffentlicht - 20 Mai 2015 |
Peer-Review-Status | Ja |
Externe IDs
Scopus | 84923572761 |
---|---|
ORCID | /0000-0002-4531-691X/work/148607951 |
Schlagworte
Schlagwörter
- Composites, Graphene and fullerenes, Morphology, Nanotubes, Polyolefins, Properties and characterization