Integrated piezoelectric function in a high thermostable thermoplastic PZT/PEEK composite

• Submicronic PZT particles have been characterized as ferroelectric.
• Good particle dispersion into the PEEK is reached by extrusion.
• Low poling field is required.
• Poling field must be applied above the glass transition temperature.

A piezoelectric structural material has been developed. Lead Zirconate Titanate (PZT) submicronic nanoparticles have been dispersed in a thermostable high performance thermoplastic polymer Poly(Ether Ether Ketone) i.e. PEEK to ensure piezoelectric properties. The inorganic particles with a mean diameter of 900 nm are polycrystalline as highlighted by HRTEM with a grain diameter estimated at 15 nm. XRD patterns have shown that the crystalline structure is rhombohedral i.e. ferroelectric. The PZT/PEEK composites have been elaborated by extrusion which allows reaching a satisfactory dispersion of particles even at high volume fraction (30% in volume). One of the challenges was to find poling conditions compatible with the thermal stability of the matrix. Indeed, this composite must be poled above the polymer glass transition temperature to improve matching of dielectric permittivity between inorganic and organic phases. The influence of the poling electric field on the final piezoelectric activity of the composite has also been studied to better understand the role of the polymer matrix. Finally, after a poling step, the PZT/PEEK composite exhibits a piezoelectric strain coefficient which can be exploited over a wide temperature range.