Preparation And Properties Of Epoxy Piezoelectric Damping Composites

Piezoelectric material is a new class of smart damping material, which was made up of piezoelectric ceramic particles, conductive particles and polymer material. The main damping way was "vibration mechanical energy? electrical energy? thermal energy", and the thermal energy dissipated to achieve the purpose of reducing vibration.Poly(3,4-ethylene dioxy thiophene) is a kind of thiophene derivatives conductive polymer materials. Using chemical oxidation method to prepare functional PEDOT/PMN powder, ferric chloride hexahydrate(Fe Cl3?6H2O) as an oxidant, and the dopant was polystyrene sulfonate(PSSNa), adding 3,4-ethylene dioxy thiophene(EDOT), lead magnesium niobate-lead zirconate-lead titanate(PMN) ceramics, oxidant and dopant into the round-bottomed flask, the mixture was stirred for 40 hours at room temperature, after the process of filtration, drying to obtain PEDOT/PMN coated powder. FTIR, XRD analysis proved the synthesis of conductive polymer PEDOT successfully. Using scanning electron microscopy to observe the microstructure of PEDOT/PMN powder, when the volume content reached about 50%, the surface of piezoelectric ceramic was completely covered by PEDOT. With the increase of the conductive polymer's volume fraction, the conductivity increased significantly, 50%(v/v) coated sample conductivity was about 2.7×10-3S/cm. The particle size analysis showed that the size of coated powder greatly decreased after a long time mixing reaction.Adding the PEDOT/PMN coated powder into epoxy resin(EP) to prepare a kind of piezoelectric damping composite, PEDOT/PMN coated powder was as the functional phase, the mechanical, electrical and damping properties were researched. When mass fraction of the coated powder was 60%, the maximum compressive strength and bending strength were 84.7 and 99.7MPa. The factors which affected the piezoelectric and dielectric properties of composite material were polarization, type of curing agent and content of functional phase. As to piezoelectric property, the more of functional powder content, the better of the piezoelectric property. When the content of functional powder was constant, PEDOT decreased the piezoelectric property. As to the dielectric property, which improved along with the increasing content of the PEDOT/PMN coated powder. The conductive property of the composite could reach level of semiconductor, when the MTHPA curing agent was used, and the functional phase was 50%(v/v) PEDOT/PMN powder, the mass fraction was 60%, the conductivity of that sample was 2.92×10-6 S/cm. Analyzing the damping property of composite, the content of functional phase ranged from 15% to 60%, the damping property improved along with the increase of the functional powder's content. When the functional filler was 50%(v/v) PEDOT/PMN powder, and mass fraction was 60%, the damping loss factor peak(?max) was 0.621, the effective damping temperature range(?T) was 36.4?.