The Effects of Concentration and Particle Size of TiO2 on the Dielectric Properties of Polyolefin-Based Microwave Substrates

Fibre-reinforced polybutadiene/ styrene-butadiene-styrene triblock copolymer/ ethylene-propylene-diene terpolymer/titanium dioxide (PB/SBS/EPDM/TiO2) composite laminates with superior dielectric properties were fabricated by impregnation and hot pressing. The effects of concentration and particle size of rutile spherical TiO2 on the microwave dielectric properties of the PB/SBS/EPDM/TiO2 composite laminates were investigated at microwave frequency region. Additionally, the mechanical, thermal, and water absorption properties of the laminates were also evaluated. Results indicated that the dielectric properties were obviously improved with the increase of concentration or the decrease of particle size. The laminate filled with 230 nm TiO2 at a filler loading of 70 wt% possessed high dielectric constant (7.03, 10 GHz), low dielectric loss (0.0042, 10 GHz), outstanding mechanical, thermal properties, and low water absorption. Enhanced dielectric properties and other prominent properties enable the fibre-reinforced polyolefin-based composite laminates to be a potential candidate for microwave substrate applications.