Preparation of PA11/BaTiO3 nanocomposite powders with improved processability, dielectric and piezoelectric properties for use in selective laser sintering

Highlights: • PA11/BaTiO₃ nanocomposite powders used for selective laser sintering (SLS) were prepared through a novel method. • The PA11/BaTiO₃ nanocomposite powders had uniform particle dispersion and good processability. • The milled PA11/BaTiO₃ nanocomposite parts had improved dielectric and piezoelectric properties. • The complex PA11/BaTiO₃ nanocomposite parts with high accuracies and good mechanical properties were fabricated. The polyamide11 (PA11)/BaTiO₃ nanocomposite powders for use in selective laser sintering (SLS) were successfully prepared through a novel method combining the techniques of solid state shear milling, melt blending and cryogenic grinding. This provided a method for the large scale and non-solvent production of functional nanocomposite powders. The related mechanism, structure and properties of the obtained composites were investigated. The results indicated that the solid state shear milling technique could efficiently realize better dispersion of BaTiO₃ nanoparticles in the PA11 matrix and improve their interfacial compatibilities, endowing the composites with better processability and electrical performance. The sintering windows (between the initial temperature of melting and crystallization) of the PA11/BaTiO₃ nanocomposites were greatly enhanced by the solid state shear milling technique, especially for the composites containing 40 wt% BaTiO₃ particles, for which the sintering window increased from 10.1 °C to 14.6 °C, providing a wide sintering window for SLS. Meanwhile, the dielectric constant (ε_r), piezoelectric strain coefficient (d₃₃) and piezoelectric voltage coefficient (g₃₃) of the SLS printed PA11/BaTiO₃ nanocomposite parts increased after the milling treatment. Finally, the complex PA11/BaTiO₃ nanocomposite parts with high dimensional accuracy and good mechanical properties were fabricated by the SLS machine.