Xu Renxin

Dielectric and Piezoelectric Properties of 0-3 PZT/PVDF Composite Doped with Polyaniline

Lead zirconate titanate (PZT)/polyvinylidene fluoride (PVDF) 0-3 piezoelectric composites doped with polyaniline (PANI) were obtained by hot-press method. The polarization properties of the composites were characterized by XRD and P-E hysteresis loops at room temperature. And the dielectric and piezoelectric properties were also measured. The results show that the poling of PZT could be effectively carried out and the dielectric constant εr, and dissipation tanδ increase monotonously by increasing the volume fraction of PANI in the composite. The piezoelectric constant d33, and the planar electromechanical coupling factor kp increase while the mechanical quality factor Qm decreases with the increase in the content of PANI. The d33, kp and Qm show the extremum values at 8 vol%-10 vol% PANI.

Isocyanate-terminated polyethers toughened epoxy resin: Chemical modification, thermal properties, and mechanical strength

The toughening of the diglycidyl ether of bisphenol A epoxy resin with isocyanateterminated polyethers (ITPE) was investigated. The progress of the reaction and the structural changes during modification process were studied using FTIR spectroscopy. The studies support the proposition that TDI (tolylene diisocyanate) acts as a coupling agent between the epoxy and polyethers, forming a urethane linkage with the former and the latter, respectively. Me THPA-cured ER/ITPs blends were characterized using dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA). It is indicated the glass transition temperature (Tg) of systems was lower than the Tg of pure epoxy resin and overfull ITPE separated from the modified epoxy resin and formed another phase at an ITPE-content of more than 10wt%. The thermal stability was decreased by the introduction of ITPE. The impact strength and the flexural strength of the cured modifiedepoxy increased with increasing the ITPE content and a maximum plateau value of about 24.03 kJ/m2 and 130.56 MPa was measured in 10wt% ITPE. From scanning electron microscopy (SEM) studies of the fractrue surfaces of ER/ITPE systems, the nature of the micromechanisms responsible for the increases in toughness of the systems was identified.