The high demand for specialized materials dictates the necessity to study polymer composites. Two fillers that have become increasingly popular are carbon microfibers and nanotubes. However, creating cost-effective final products can be difficult with the expensive nature of Multi-Walled Carbon Nanotubes (MWCNT). A multi-scale processing approach, which includes certain concentrations of both fillers, has been developed to help mitigate those issues without losing the material property enhancements. The following paper studies the relationship between filler ratios and die geometry on the material properties of the extruded multi-scale polymer composite.
For this experiment two slit die geometries, one with a parallel land length and one with a diverging land length, were utilized to extrude varying weight percentage combinations of multi-scale polymer composites. The purpose of studying these two different geometries was to observe how the reorientation of the microfibers caused by the divergence of the flow would affect the material properties of the extruded composites. Testing of the extrudate was primarily focused on the tensile strength and thermal conductivity of the material. However, also of interest were the distribution of the fillers and the orientation of the microfibers with respect to the direction of flow, which were both observed using microscopy and image processing.
The analysis of the reorientation, filler distribution, and material property enhancement was then used to formulate fundamental processing-structure-property models of multi-scale polymer composites based on the die geometry and the concentrations of fillers present.
