Effect of Graphite Nanoplate Morphology on the Dispersion and Physical Properties of Polycarbonate Based Composites

Abstract

The influence of the morphology of industrial graphite nanoplate (GNP) materials on their dispersion in polycarbonate (PC) is studied. Three GNP morphology types were identified, namely lamellar, fragmented or compact structure. The dispersion evolution of all GNP types in PC is similar with varying melt temperature, screw speed, or mixing time during melt mixing. Increased shear stress reduces the size of GNP primary structures, whereby the GNP aspect ratio decreases. A significant GNP exfoliation to individual or few graphene layers could not be achieved under the selected melt mixing conditions. The resulting GNP macrodispersion depends on the individual GNP morphology, particle sizes and bulk density and is clearly reflected in the composite’s electrical, thermal, mechanical, and gas barrier properties. Based on a comparison with carbon nanotubes (CNT) and carbon black (CB), CNT are recommended in regard to electrical conductivity, whereas, for thermal conductive or gas barrier application, GNP is preferred.

Thermal Conductivity and Electrical Resistivity of Melt-Mixed Polypropylene Composites Containing Mixtures of Carbon-Based Fillers

“…In addition, such stacks may orient during the shaping process parallel to the sample surface. The shape and orientation of the particle agglomerates was not quantified in the present study; however, an orientation of the graphite particles in the in-plane direction was described in previous studies [53,54]. In case of filler orientation in the in-plane direction, the thermal conductivity will also be higher in this direction and significantly lower when measured through the plane (the direction of measurement in our study).…”

“…Although the GNP are flake-shaped, they form agglomerates with a particle-like structure in the composites that is similar to graphite, as illustrated in ref. [54]. Thus, they were also considered in a simplified way as spherical particles.…”

Electrical and melt rheological characterization of PC and co‐continuous PC/SAN blends filled with CNTs: Relationship between melt‐mixing parameters, filler dispersion, and filler aspect ratio

“…Melt mixing of carbon nanotubes (CNTs) into thermoplastic polymers to generate composites with electrostatic discharge or conductive behavior has found increasing interest during the last two decades. In particular, composites based on the amorphous polycarbonate (PC) matrix have been widely investigated due to the relatively good dispersability of CNTs in this matrix polymer and the importance of PC as material for housing applications. However, the desired high electrical conductivity of the composites at applicable CNT contents could not always be achieved, even at good filler dispersion.…”

Barrier Properties of GnP–PA-Extruded Films

“…This is necessary for investigation of graphene nanocomposite preparation in a scale adaptable to commercial processes, like compounding on a twin screw extruder and film extrusion. A survey on possible structures derived in polycarbonate with GnP available in an industrial scale is given by Poetschke and coworkers [16]. Another report uses graphene-like materials in high-density Polyethylene (HDPE) on large scale compounding machinery…”