Morphology, mechanical and damping properties of BaTiO₃/(PU/UP- IPNs) composites

A series of BaTiO₃/ Interpenetrating polymer networks (IPNs) composites, composed of BaTiO₃ fibers synthesized by hydrothermal method and simultaneous IPNs based on polyurethane (PU) and unsaturated polyester resin (UP), were prepared by in-situ polymerization process. Fourier transform infrared spectroscopy (FTIR) was used to trace polymerization process of IPNs and transmission electron micrographs (TEM) was used to characterize the morphology and miscibility among multiple phases of IPNs and composites. The results indicated that the domains between two phases in IPNs were constricted in nanometer scales, and BaTiO₃ dispersed in composites mostly with fiber structures. The damping property studies of IPNs and composites revealed that, the value of loss factor (tanδ) and loss modulus (E″) detected by dynamic mechanical thermal analyzer (DMTA) both increased with the adding amounts of BaTiO₃ in composites, and the shoulder peak of tanδ and E″ curves both appeared apparently at low temperature ranges. Maximum tanδ values of all composites were above 0.4 and the maximum E″ values of composites increased above 100 MPa in nearly 50°C ranges compared with that of IPNs. The mechanical properties study showed that the continuous phase of IPNs accounted for the major mechanical properties and the adding of BaTiO₃ both decreased the values of tensile strength and elongation at break of composites.