Investigation of filling amount and particle size on electrical conductivity of silver conductive composite

Printable conductive composites show potential in wearable electronic, capacitor, stretchable sensors, and conductors. Incorporating metal nanoparticles in composites is a leading method to achieve high performance. In this study, we present a method for preparing silver flakes with ultra-smooth surfaces and excellent electron transfer properties by combining a waterborne acrylic resin template method with an intensive energy ultrasonic technique. By varying the ultrasonic treatment time from 20 to 80 min, the size distribution of the silver flakes was controlled, ranging from 15.7 to 5.04 μm. Scanning electron microscopy results indicate that the intensive energy ultrasonic treatment does not affect the surface morphology of the silver flakes. Additionally, the electron transport difficulties arising from internal defects in silver flakes prepared by traditional methods have been mitigated. The influence of size distribution and filler content on the electrical conductivity of silver conductive composites has been investigated. The study identified a correlation between the particle size distribution of flake silver powder and the volume resistivity of the conductive composite material, wherein a reduction in particle size distribution leads to a corresponding decrease in volume resistivity. Furthermore, an increase in the filler content of the composite material was found to result in a reduction in its volume resistivity. Using flake silver powder with a median particle size (d_0.5) of 5.38 μm as a representative sample, the volume resistivity was observed to increase from 8.50 × 10⁻⁵ Ω·cm to 8.63 × 10⁻³ Ω·cm as the silver content was decreased from 25 to 4 wt %. Concurrently, an examination of the conductive properties and the formation of the conductive network demonstrated alignment with the theoretical steady-state model.

Graphical Abstract

Silver flakes with ultra-smooth surface and excellent electron transfer property is prepared by combining vacuum-evaporated nanofilms method and intensive energy ultrasonic technique.