Study On The Preparation And Properties Of Polymide-based Composites Film

With the development of the science and technology, the more requires to materials are put forward. Polyimide (PI), as a typical kind of engineering polymer material with superior properties, has widely been used in the aviation and microelectronic industries because of its outstanding performances. Barium titanate (BaTiO₃) is a dielectric material, with a perovskite (ABO₃) structure,it is the primary material for high dielectric constant ceramic capacitors due to its excellent electronic performance,such as ferroelectric, piezoelectric, high dielectric constant and positive temperature coefficient effect, etc. Then the research of preparation and dielectric properties of doped barium titanate has been a focal point in the field of electronic ceramics. Organic/inorganic composite materials have obtained more and more attentions in the fields of mechanics, thermodynamics, optics, electromagnetics and biology etc, because of their excellent characteristics and properties. Polymer/Ceramic composite is a kind of most promising electric materials,which combines the virtues of both ceramic materials and polymer materials. Via optimization of technical crafts,it is hopeful to get high-dielectric-permittivity composite materials with good mechanical properties and molding easiness.In this work, Polyimide (Pl) with excellent thermal properties was chosen as the matrix phase of the composites, BaTiO₃ and (BaCa) ZrTiO₃ are chosen as the disperse phase of the composites. Pl/BaTiO₃ and PI/ (BaCa) ZrTiO₃ composite films are synthesized by solution mixing technique and in-situ polymerization technique, respectively. Thermal stability property and surface appearance of the composite films were characterized and analyzed by TGA, and AFM etc. The main points studied in the paper are listed as following:1. Polyimide /BaTiO₃ composite films are synthesized by solution mixing technique and in-situ polymerization technique, respectively. Several tests of the films were carried out including TEM,AFM,XRD,TGA and dielectric properties.Thermal stability properties of the films by the two methods have been increased. Experimental results showed that particles distributed evenly throughout polymide and the crystal structure of particles did not change.The influences of the technical crafts on the dielectric properties of the composites are also studied. The dielectric properties of PI/ BaTiO₃ composites films by in-situ polymerization technique preferred to films by solution mixing technique, at room temperature, 1KHZ, dielectric permittivity is 19.The BaTiO₃ particles could more homogenously dispersed in polyimide matrix,it is main reason.2. PI/ (BaCa) ZrTiO₃ composite films are synthesized by solution mixing technique and in-situ polymerization technique, respectively. Several tests of the films were carried out including TEM,AFM,XRD,TGA and dielectric properties. Experimental results showed that particles distributed evenly throughout polymide and the crystal structure of particles did not change.With the increase of (BaCa)ZrTiO₃, the composite films'thermal stability , dielectric constant and dielectric loss were increased.The dielectric properties of PI/ (BaCa) ZrTiO₃ composites films by in-situ polymerization technique preferred to films by solution mixing technique. At room temperature, 1KHZ, dielectric permittivity is 25.