New piezoelectric composites based on isotactic polypropylene filled with silicate

Abstract

Polymeric cellular composites are very important materials in modern electronics because they can be used as piezopolymers due to low specific weight, good thermal resistance and high value of piezoelectric constant d33. The aim of this work was to obtain and characterize the cellular polypropylene (PP) composites as materials designed for microelectronics. PP has been modified by addition of commercial silicate filler and the obtained materials were extruded. Then, the composites were subjected to electric field for polarization. Effect of the filler content on the structure and physicochemical properties of the composites have been investigated. The following experimental methods have been applied: SEM, XRD, thermogravimetry, tensile tests and measurements of voltage and electric charge accumulated in the polymer. The piezoelectric constant and stability of piezoelectric properties were also determined. It was found that the growth in the filler content in the polymer causes the increase in the film porosity and the degree of PP crystallinity that reaches 70% for the PP sample with 10% of the filler. Young’s modulus increased also in the presence of the filler. Moreover, the thermal stability of the composites was improved compared to neat PP. The piezoelectric constant of the composites was about 200 pC/N).