Study On Preparation And Properties Of Piezoelectric-damping/Epoxy Composite

When doing research on piezoelectric-damping composite materials, the traditional methods is to use carbon black powder or metal powder as the conductive component. Conductive powder, piezoelectric ceramic powder and resin are mixed together and then cure. In this thesis a new method is employed which is totally different from the previous way. Conductive polymer PANI is used as the conductive component. First, PMN powder which is the piezoelectric component is completely wrapped in PANI through in situ synthesis. Then as functional component, the PANI-wrap-PMN powder is mixed with epoxy resin and then cure. The content of PANI in composite can be ajusted, increasing the flexibility of design of composite.The following results are found by research:1. PMN powder can be successfully wrapped in PANI through in situ synthesis. The proper synthesis conditions are 0℃and 24h. PMN powder can be totally wrapped in PANI, if the volume content of PANI is over 30 percent. The sample's conductance can be as high as 10^-4 S/cm.2. The conductance of samples of PANI/PMN/EP inreases as the content of PANI/PMN powder increases in composite sample, but the samples'compression intensity decreases.3. Electric breakdown voltage of the samples decreases with the increase of PANI in composite. The composite samples can be easily destroyed by high voltage, when volume content of PANI in composite is over 10 percent, making the sample hardly to be polarized. The piezoeletric constant(d₃₃)of samples increases as the content of PANI/PMN powder increases. The extension of polarization time can also inrease the samples 'd₃₃. In addition, polarization of samples inreases dielectric constant(e), but has no obvious influence on samples' dielectric loss(tan d).4. Both the samples' dielectric constant(e) and dielectric loss(tan d) increse as the increase of content of PANI/PMN powder in samples. Low content of PANI results in increase of dielectric constant, but high content makes a drop.5. The damping loss of samples including PANI is higher than that of samples without PANI. Polarization of samples also can increase the damping loss.