Surface Modification of Copper-Based Flakes for Conductive Polymer Composites

Area of Science:

• Materials Science
• Polymer Science

Background:

• Surface protection of copper particles enhances thermal and electrical stability.
• Coating material choice is crucial for optimizing copper particle properties in polymer composites.

Purpose of the Study:

• To characterize rheological, thermal, mechanical, and electrical properties of polymer composites containing uncoated (Cu), silver-coated (Cu@Ag), and silica-coated (Cu@Si) copper flakes.
• To investigate the effect of different surface coatings on particle interactions, percolation thresholds, and electrical conductivity.

Main Methods:

• Preparation of low-density polyethylene composites with varying volume concentrations (up to 40%) of Cu, Cu@Ag, and Cu@Si flakes.
• Rheological, thermal, mechanical, and electrical characterization of the composites.
• Analysis of particle interactions and network formation through rheological properties.

Main Results:

• Geometrical and electrical percolation occurred at ~15% for Cu and Cu@Si, but surprisingly lower (~7.5%) for Cu@Ag due to silver coating fusion.
• Coating materials did not enhance load transfer for mechanical reinforcement.
• Cu@Ag exhibited significantly superior electrical conductivity (74.4 S/m) compared to Cu (1.7 × 10^-4 S/m) and Cu@Si (1.5 × 10^-10 S/m).

Conclusions:

• Surface coating significantly influences the electrical percolation threshold and conductivity of copper-polymer composites.
• Silver coating on copper flakes is highly effective in enhancing electrical conductivity for electronic applications.
• The findings are vital for designing advanced polymer composites with tailored electrical properties.